WAU K E S H A ® T R A N S F O R M E R S
Waukesha UZD LTC Technical Manual
®
®
LOA D TA P C H A N G E R T Y P E “ U Z D R T ”
The intent of this Technical Guide is to allow transformer manufacturers—and their designers and engineers—access to all technical
information required to assist them in designing transformers using the Waukesha® UZD® Load Tap Changer. The information contained in
this document is meant to be general and does not cover all possible applications. Any specific application not included should be referred
directly to SPX Transformer Solutions, Inc. (including Waukesha® Components) or its authorized representative.
SPX Transformer Solutions, Inc. makes no warranty or representation and assumes no liability for the accuracy of the information in this
document or for the use of such information. All information in this document is subject to change without notice.
Table of Contents
G E N E RAL D E SCR I PTION
Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
C O N S T R U CT I O N
Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
LTC Tank Oil-Filled Compartment – Tap Changer Live Parts. . . 6-11
Over-current Blocking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Epoxy Phase Moldings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7
Indication. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Arcing Tap Switch (Tap Selector Switch) . . . . . . . . . . . . . . . . . . . . . . . 8
Wiring and Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Reversing Change-Over Selector (Reversing Switch). . . . . . . . . . . 8
Optional Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Transition Resistors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
LTC Tank Air-Filled Compartment–Spring Drive Mechanism. . 12-15
Drive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Flywheel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Geneva Gear. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Reversing Change-Over Selector Geneva Gear . . . . . . . . . . . . . . 14
UZD® Tank - External . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-19
Weight and Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-17
Tank and Accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-19
BUE Motor Drive Mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-27
Cabinet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Gearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Hand Crank. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
One-turn Shaft. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Position Indicator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2
O P E R AT I N G P R I N C I P L E S
Load Tap Changer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28-33
Switching Sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Arcing Tap Switch (Tap Selector Switch). . . . . . . . . . . . . . . . . . . . . 28
Reversing Change-Over Selector for Plus/Minus Switching. . . 31
Through-positions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Schematic Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Motor Drive Mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33-37
Operational Description – Schematic. . . . . . . . . . . . . . . . . . . . . 33-35
Contact Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Local Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Remote Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Automatic Operation Local Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Over Current Relay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
Through-positions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
Step-by-Step Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Mechanical and Electrical End Stops. . . . . . . . . . . . . . . . . . . . . . . . . 24
T E C H N I CA L DATA & C H A R ACT E R I S T I C S
Contact Device. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Ratings - Insulation Level. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Continuation Contact (84C). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Transition Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Maintaining Contact. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Standards and Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Interlocking Contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Rating Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Auxiliary Contact. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Step Voltage and Through Current. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Brake. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Mechanical Life. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Indicator Flag. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Contact life. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Maintaining Contact Brake. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Reverse Power Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Start Contact. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Short Circuit Strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Operation Counter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Loading Beyond Nameplate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Mineral Oil/FR3 Fluid Operating Temperatures. . . . . . . . . . . . . . . . . 41
Tie-in Resistors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Sound Level. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Operation at Lower and Higher Ambient Temperatures . . . . . . . . . 42
Conductors from Windings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Grounding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Cable Lugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
A S S E M B LY TO T R A N S F O R M E R & C O M M I S S I O N I N G
Receiving Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Unpacking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Product Verification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Damage Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Moisture Evaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Temporary Storage Before Assembly. . . . . . . . . . . . . . . . . . . . . . . . 43
Preparation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Welding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
BUE Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45-49
Lead Connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50-51
Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50-15
Assembly of Accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Conversions of Metric Measures Torque . . . . . . . . . . . . . . . . . . . . . 52
Oil Preservation – ARDB2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53-54
On-Line Oil Filtration – OF2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55-57
Pressure Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58-59
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Design and Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Mounting and Connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Adjusting and Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
LTC Oil. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60-62
Acceptance Test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Determination of Quantity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Oil Filling Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61-62
Shipping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Electrical Connection and Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Connecting and Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Electrical Test on Transformer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Field Commissioning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
G LO S S A RY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64-65
A P P E N D I X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
3
General Description
The UZD® is an externally mounted load tap changer intended for application on liquid-filled power transformers for varying the
transformer’s turns ratio while energized and carrying load. UZD® is a three phase, fully insulated, 33 position switch designed for
plus/minus operation by use of a reversing change-over selector switch. UZD® is a “High Speed Resistance Bridging (Transition)”
Tap Changer, meaning it employs a resistor for the transition impedance, limiting the circulating current in the bridging position when
two adjacent taps are bridged during a tap change operation. The arcing that occurs during a tap change operation takes place in the
insulating liquid. An on-line oil filtration system is recommended to keep the oil clean, increase reliability and extend maintenance cycles.
To increase contact life and reduce maintenance, the WAUKESHA UZD® load tap changer has separate arcing contacts and main
current-carrying contacts on the same moving arm. With the Waukesha UZD®, all arcing is shunted across three sets of rolling contacts
and stationary arcing contacts. The stationary arcing contacts are made of special arc-resistant alloys. There is no arcing across the
main current-carrying contacts.
The UZD® is designed to be mounted on the outside of the transformer tank. All equipment necessary to operate the tap changer is
contained in this compartment and the attached BUE motor drive mechanism. This arrangement allows the transformer tank to be
designed significantly smaller than a transformer with the load tap changer mounted inside the transformer tank (less plate steel and less
oil). This arrangement also allows for simpler transformer assembly. The voltage regulating relay is provided by the transformer OEM and
typically mounted in the main transformer control cabinet.
The UZD® has two compartments: the oil filled switching compartment on the left hand side, which houses the tap selector and the
reversing change-over selector, and the air-filled compartment on the right hand side which houses the spring
drive mechanism.
The WAUKESHA UZD® LTC compartment holds 100 gallons of oil. The WAUKESHA UZD® LTC oil compartment is designed with a
sloped sump at the bottom of the compartment and a lip on the front door. Thus, all the oil can be drained from the compartment and
oil does not spill out when you open the front door. Also, cleaning the inside of the tap changer (spraying oil to clean the contacts, for
example) can be done easily with the door open. The oil drains through the drain valve at the bottom of the sump.
The BUE motor drive mechanism is a separate compartment mounted below the spring drive mechanism at eye level with a driveshaft
connecting the motor drive mechanism to the spring drive mechanism. The cabinet utilizes a split, half-box cover design for easy access
to the interior. All wiring points which might be of interest to the user should be wired to the main control cabinet by or the transformer
OEM. This reduces wiring time in the field.
The WAUKESHA UZD® LTC utilizes a spring-loaded drive mechanism to make all tap position changes. The main drive motor charges
the spring battery which makes the tap change–not the motor itself. This drive mechanism design limits arcing time to about 6
milliseconds with a total time to change taps of approximately 70 milliseconds. The spring drive also insures that if control power is
lost or the motor fails, the LTC will not remain in an off-contact position. Furthermore, the Geneva gear drive system in the spring drive
compartment of
the Waukesha UZD® assures that for one full revolution of the fly wheel (connected to the spring battery), the contact arm will move only
1/18 of a revolution providing positive contact alignment on each tap position. The motor takes approximately 6 seconds to charge the
spring battery.
4
The WAUKESHA UZD® LTC may be manually operated under load. Thus, with a loss of power to the motor, the Waukesha UZD® is still
capable of changing tap positions by manual operation of the crank handle which charges the spring-loaded drive mechanism defined in
the previous paragraph. The speed at which the hand crank is turned manually has no bearing on the speed at which the contacts move
on the Waukesha UZD® as this is determined by the energy stored in the spring drive. When the spring battery is moved past top dead
center, the tap change will occur at normal speed regardless of hand crank speed.
UZD® conforms to IEEE C57.131-1995 and IEC 60214-1.
5
Construction
FIGURE 1: UZD® WITH BUE UNIT ATTACHED
FLANGE FOR OPTIONAL
UPPER FILL VALVE
FLANGE FOR OPTIONAL
PRESSURE RELIEF DEVICE
FLANGE FOR OPTIONAL
RAPID PRESSURE RISE RELAY
OIL LEVEL
INDICATOR
PRESSURE
RELAY
WELL FOR
OPTIONAL
TEMPERATURE
PROBE
SPRING DRIVE MECHANISM
DRAIN
INLET PIPE FOR
OIL FILTRATION
TRANSITION RESISTOR
SWITCHING COMPARTMENT
BUE MOTOR DRIVE
MECHANISM
LTC TA N K - O I L C O M PA R T M E N T - TA P C H A N G E R L I V E PA R T S
Epoxy Phase Molding
Three (one per phase) one-piece, cast Epoxy Phase moldings Figure
recessed gasket groove molded into the epoxy. The Phase moldings
2, mount inside the liquid filled compartment. The Tap selector switch
are held in place against the back wall with studs, nuts and clamps.
assembly, Reversing change-over selector switch (reversing switch)
6
assembly and the Transition resistors are mounted on these Phase
The gasket prevents oil exchange between the UZD® oil and the
moldings. Bearings for the operating shafts of the Moving tap
transformer oil. Copper rods are embedded in the Phase moldings
selector switch and the Reversing change-over selector switch are
and allow the Phase moldings to act as bushings, connecting
also embedded in the phase moldings. These Phase moldings are
contacts in the liquid filled compartment with cables in the
sealed to the back of the tap changer tank with O-ring gaskets in a
transformer tank.
FIGURE 2: CAST EPOXY PHASE MOLDING WITH CONTACTS ASSEMBLED
ITEM 6
MOVING REVERSING CHANGEOVER
SELECTOR SWITCH ASSEMBLY
ITEM 4
SLIP CONTACTS
(BOWTIE CONTACTS)
ITEM 5
STATIONARY REVERSING
CONTACT (2X)
TRANSFORMER
CONNECTING
TERMINAL
TRANSITION
RESISTORS
ITEM 3
MOVING SELECTOR
SWITCH ASSEMBLY
ITEM 4
SLIP CONTACTS
(BOWTIE CONTACTS)
O-RING GASKET
ITEM 1
CAST EPOXY MOLDING
ITEM 2
STATIONARY CONTACT (18X)
The transformer manufacturer connects winding leads to these
On each Phase molding, 18 Stationary contact assemblies are
terminals of the Phase molding, without requiring opening of the
mounted in a circle Figure 2, Item 2. The Moving contacts Figure 2,
tap changer. Connections are made from inside the transformer
Item 3 of the Tap selector switch assembly are mounted on a drive
tank after the core and coil assembly has been fitted and prior to
shaft running through the center of the Phase molding. At the top
oil filling. The terminals are numbered for proper identification.
of the Phase molding are the two Stationary reversing change-over
These connections are made via a special crimp-on cable connector
selector contacts Figure 2, Item 5 and the Moving reversing change-
supplied with the UZD . There are different sized connectors to
over selector switch assembly Figure 2, Item 6 mounted on a drive
fit different cable sizes. The transformer OEM must specify the
shaft running through a bearing in the Phase molding. Adjacent
cable size.
to each of the two drive shafts is a Slip contact (bowtie contact)
®
Figure 2, Item 4 assembly that transfers the current from the moving
contacts to the copper rods in the Phase moldings.
7
Arcing Tap Switch (Tap Selector Switch)
Reversing Change-Over Selector (Reversing Switch)
The Tap selector switch consists of the Stationary contacts Figure
Each phase includes a single pole, double throw Reversing
3 mentioned above and a Moving contact assembly Figure 4. The
change-over selector (reversing switch) near the top of each
Stationary contacts are mounted on a bracket which is secured
Phase molding Figure 5. This slow speed switch is arranged by
to terminals embedded in the Phase moldings. There are two
internal drive gearing to change over at a circuit position where it
operating sections of the Stationary contacts. The middle section
does not carry current. The Reversing moving contacts Figure 5,
of the contact is constructed of silver-plated copper and is where
Item 2 are driven by the Motor drive mechanism through a Geneva
the moving contacts rest when the tap changer is in the “on”
gear connected by a Reversing drive shaft Figure 5, Item 3 which
position. The leading and trailing edges of the Stationary contacts
enters the liquid filled space though an oil seal. The Geneva gear
are copper-tungsten arcing tips brazed on to the copper body
ensures correct indexing, and locks the moving contacts in position
prior to silver plating and mate with the moving copper/tungsten
at each tap.
arcing roller contacts during a tap change operation. All arcing
happens on this area of the stationary contacts and the arcing
In order to effect self-cleaning of the contact surfaces, the
roller contacts.
movement of the reversing switch is arranged in three stages,
during which the reversing switch does not make or break a
The Moving contact system consists of the main current carrying
current. In the first stage, the Reversing moving contact Figure 5,
contact Figure 4, Item 2, the Main switching contact Figure 4,
Item 2 wipes along the face of the Reversing stationary contact
Item 3 and two Transition contacts Figure 4, Item 4. The center
Figure 5, Item 1. In the second stage, the Reversing moving
contacts are insulated from the two outer contacts and built
contact breaks with the Reversing stationary contact and makes
together as a rigid unit rotated by a common drive shaft. The three
with the edge of the other Reversing stationary contact. In the
phase drives are inter-linked phase-to-phase by epoxy couplings
third stage, the Reversing moving contacts wipe the face of the
Figure 6, Item 5 that provide flexibility in alignment between
Reversing stationary contact until reaching the final position.
phases. At the right end, the drive is connected through an oil
This wiping action is intended to keep the contacts clean of film
seal to a Geneva gear in the air-filled spring drive compartment.
buildup. The sequence is seen clearly in Figures 19A, 19B and
The Geneva gear ensures correct indexing and locks the moving
19C, page 32.
contacts in position at each tap. In the stationary operating
position, the through current is carried by the main current carrying
The reversing switch connects the regulating (tapping) winding to
contact, which consists of two opposing contact fingers pressed
the main winding, such that the voltage generated in the regulating
onto the stationary contact by springs. The Main moving switching
winding either adds to or subtracts from the voltage produced in
arcing rollers and the Transition arcing roller contacts roll up the
the main winding. This doubles the duty of the stationary selector
ramp shape of the arcing tip brazed into the Stationary contacts.
switch contacts and of the turns in the regulating (tapping)
The making and breaking takes place between the stationary and
winding so that 16 taps produce 32 different voltages. See typical
moving roller contacts.
Connection Diagram, Figure 20D, page 33.
Current collected by the main moving contacts passes directly to
a slip contact (bowtie contact) Figure 2, Item 4 near the center of
the Phase molding, and goes back to the transformer through bus
bars embedded in the Phase molding.
8
FIGURE 3:
STATIONARY
CONTACT
FIGURE 4: MAIN
MOVING CONTACT
ASSEMBLY WITH
TRANSITION
RESISTOR
9
Transition Resistors
The Transition resistors Figure 4, Item 1 are made from resistor wire wound on insulating bobbins.
They are connected between the Main current carrying contact and the Transition arcing roller
contacts and rotate with the selector switch. The resistance value is determined by the transformer
design and will be selected by SPX Waukesha. Resistance valves are typically in the range of 0.1Ω
to 5.0Ω.
FIGURE 5: REVERSING
CHANGE-OVER SELECTOR
(REVERSING SWITCH)
ITEM 1
REVERSING
STATIONARY
CONTACT (2X)
ITEM 3
REVERSING DRIVE SHAFT
ITEM 4
SLIP CONTACTS
(BOWTIE CONTACTS)
ITEM 2
REVERSING
MOVING
CONTACT
10
FIGURE 6: MAIN SWITCH AND SPRING DRIVE COMPARTMENT
ITEM 1
FLANGE FOR OPTIONAL
INTEGRATED OIL
FILTER PUMP MOTOR
ITEM 2
REVERSING SWITCH DRIVE
MECHANISM
ITEM 3
SPRING DRIVE
MECHANISM
ITEM 4
DRIVE SHAFT
ITEM 5
INSULATING EPOXY
DRIVE COUPLING
ITEM 6
BUE MOTOR DRIVE
11
LTC TA N K - A I R F I L L E D C O M PA R T M E N T – S P R I N G D R I V E M E C H A N I S M
Drive
Flywheel
In the following paragraph, numbers in parentheses refer to item
In the following paragraph, numbers in parentheses refer to item
numbers in Figures 7A and 7B.
numbers in Figures 7A and 7B.
The Spring Drive Mechanism is housed in an air compartment on
The Flywheel shaft (10) is held by a bearing mounted in support
the right side of the UZD (when facing the front of the UZD ). The
(15). The flywheel (9) is used to “even out” the spring battery
spring drive accepts power from the BUE Motor Drive Mechanism
energy to give a smooth contact movement and to ensure the same
mounted below it. This power is transmitted from the BUE to the
contact speed is maintained. The Flywheel movement does not
spring drive via a Drive shaft (1) contained in a housing. The Drive
need to stop simultaneously with the Spring operator crank but can
shaft turns five revolutions per tap change and stores energy in
continue within the Flywheel’s slot length. At the end of the tap
a Spring battery (8) by putting the springs in tension. The Drive
change operation, excess energy is absorbed by a Disc brake (11)
shaft (1) drives the Spring operator crank (6) through a right angle,
applied to the Flywheel. The Disc brake is operated by rollers that
conical Bevel gear set (2) and (3) with a 5:1 gear reduction. The
emerge from cam slots in the Flywheel to release the brake just as
Spring operator crank (6) rotates Drive pin (7) which charges the
the spring battery discharges, and then roll back into the cam slots
Spring battery (8) to discharge 90° without interference from the
to reapply the break about 180º later.
®
®
driving gear set. Once the Spring operator crank (winding eccentric
cam) connected to the Spring battery passes top dead center, the
If a fault occurs in the Springs (8), the operation is carried through
springs will collapse and transmit their stored energy to a Flywheel
directly by the motor.
(9). As the Spring operator crank charges the springs during its
rotation, the Flywheel and Flywheel shaft (10) are driven by means
There are two Geneva gears in the spring drive compartment.
of the Driving pin (7) so that the Disc brake (11) will be released
The first Geneva gear (13) drives the selector switch. The second
just as the spring battery discharges. The Driving pin (7) moves
Geneva gear (18) drives the Reversing change-over selector.
within the length of a 150° backlash slot in the Flywheel (8). With
continued driving, the springs are released and the Spring operator
The Flywheel (9) turns one full revolution per tap change, into a
crank (6) quickly pulls the Flywheel around.
Geneva gear (13). The Geneva gear principle is used to change the
rotary motion into a stepping motion. The Geneva gear is also used
to lock the moving contact system when in position.
12
FIGURE 7A: SPRING DRIVE MECHANISM
LEG E N D
ITE M S FOR FIG U R E 7A AN D 7B
1) S HAFT COU PLI NG AN D S HAFT
2) B EVE L G EAR (S MALL)
3) B EVE L G EAR (LARG E)
4 ) CA M S H A F T
5) G EAR D R IVE SU PPORT
6 ) S P R I N G O P E R ATO R C R A N K
7) D R IVE PI N
8 ) S P R I N G BAT T E RY
9 ) F LY W H E E L
1 0 ) F LY W H E E L S H A F T
11) D I S K B RAKE
1 2 ) G E N E VA G E A R D R I V E
1 3 ) G E N E VA G E A R
1 4 ) LTC S H A F T
15) D R IVE SU PPORT
1 6 ) BAC K L A S H C O U P L I N G
1 7 ) G E N E VA G E A R D I V E
1 8 ) G E N E VA G E A R
19) CONTROL D I S K
2 0 ) C H A N G E - OV E R A R M
21) COU PLI NG S HAFT
22) S HAFT
23) B EAR I NG HOUS I NG
13
Geneva Gear
Reversing Change-Over Selector Geneva Gear
In the following paragraph, numbers in parentheses refer to item
Two drive shafts penetrate the wall between the air-filled
numbers in Figures 7A and 7B.
spring drive mechanism compartment and the oil-filled switch
compartment. One shaft (14) drives the selector switch and the
The Geneva gear drive (12) rotates both the Geneva gear (13) and
other Shaft (22) drives the reversing change-over selector.
selector switch shaft (14) one step. After this movement, which
corresponds to one tap change operation, the Geneva wheel is
Referring to Fig. 7A and 7B, a cam is located at the end of shaft
locked by the control device on shaft (10). Shaft (14) goes through
(4), which drives the backlash coupling (16), which drives a Geneva
a Bearing housing in Drive support (15) into the oil filled switch
gear drive pin (17). The backlash coupling is freely mounted in
compartment. The bearing housing includes both bronze bearings
support (5). The Geneva gear drive (17) rotates a Geneva gear (18)
and oil seals.
one step per tap change operation, after which the Geneva gear is
locked by the center of the drive on the backlash coupling (16). The
The energy necessary to make a tap change is delivered entirely
Geneva gear (18) with control disc (19) is freely mounted on a shaft
from the Springs (8), independent of motor operation. The spring
which is fixed in support (5). The Control disk (19) prevents the
drive allows the speed of the selector switch to be independent of
change-over arm from moving until a neutral position is reached.
the external means of motive power, e.g. motor or manual crank
handle. This feature allows the UZD® to be operated manually via
When the tap changer arms have completed one revolution and
the crank handle, even when the transformer is energized and fully
just prior to leaving the last contact, control disc (19) moves the
loaded. In the event of an auxiliary power supply failure, the drive
change-over arm (20) to its other position. The drive is transferred to
motor will stop and the spring battery will slowly relax or continue
shaft (22) by means of a coupling shaft (21), which passes into the
through the tap change (if the springs have already started to
tap changer tank through a bearing housing (23). During a change
discharge). In either case, the selector switch and/or reversing
of direction, the Geneva gear (18) remains stationary for one step
switch will always be in the proper operating position.
due to the free gearing in the backlash coupling (16), allowing the
reversing switch to operate first after the tap changer has left the
last contact even with operations in the opposite direction.
14
FIGURE 7B: EXPLODED SPRING DRIVE MECHANISM (SOME ITEMS SHOWN IN CUTAWAY MODE FOR CLARITY)
LEG E N D ITE M S FOR FIG U R E 7A AN D 7B
1) S HAFT COU PLI NG AN D S HAFT
1 3 ) G E N E VA G E A R
2) B EVE L G EAR (S MALL)
1 4 ) LTC S H A F T
3) B EVE L G EAR (LARG E)
15) D R IVE SU PPORT
4 ) CA M S H A F T
1 6 ) BAC K L A S H C O U P L I N G
5) G EAR D R IVE SU PPORT
1 7 ) G E N E VA G E A R D I V E
6 ) S P R I N G O P E R ATO R C R A N K
1 8 ) G E N E VA G E A R
7) D R IVE PI N
19) CONTROL D I S K
8 ) S P R I N G BAT T E RY
2 0 ) C H A N G E - OV E R A R M
9 ) F LY W H E E L
21) COU PLI NG S HAFT
1 0 ) F LY W H E E L S H A F T
22) S HAFT
11) D I S K B RAKE
23) B EAR I NG HOUS I NG
1 2 ) G E N E VA G E A R D R I V E
15
FIGURE 8A: DIMENSIONS FOR EXTERNAL UZD® TANK
88.6 [2250] MAX BUE DOOR SWING
TRANSFORMER ATTACHING FLANGE
26.8
[680]
39.4
[1002]
63.0
[1600]
MAX
36.7
[932]
BUE DOOR SWING
UZD DOOR SWING
29.0
[738]
26.8
[680]
72.4
[1838]
MIN
67.6
[1718]
25.9
[657]
U Z D ® TA N K - E XT E R N A L
Weights and Dimensions
Dimensions in Figure 8 below show inches first with millimeters in parentheses. If only one number is given it is in millimeters.
UZD® weight without oil = 1,437 lbs (652 kgs)
BUE Motor Drive Mechanism weight = 260 lbs (118 kgs)
UZD® without oil + BUE weight total = 1,697 lbs (770 kgs)
UZD® holds 100 US gal liquid. Weight of 100 gal mineral oil = 750 lbs (341 kgs)
Total weight of UZD® + BUE + mineral oil = 2,447 lbs (1111 kgs)
16
FIGURE 8B: DIMENSIONS FOR MOUNTING BRACKET ON BOTTOM OF BUE TO TRANSFORMER TANK WALL USED
FIGURE 8C: DIMENSIONS FOR CONDUIT
WITH AN OFFSET SHAFT EXTENSION
ENTRANCE IN BACK OF BUE
20
50
REF
9.53
370
REF
6
80
R4
50
40
TYP
17
TYP
R8
R8
16
17
50
17
1-1/2" SERIES
257 PHOENIX
FLANGE INTERNAL
NPT THREAD
40
16
215
BEND UP 90
SAW AFTER BENDING
A
430
152.0
[ 6.0 ]
205.2
[ 8.1 ]
16
40
50
17
16
50
16
17
420
(measurement varies per transformer)
FIGURE 8D: TYPICAL LOCATION OF UZD® ON TRANSFORMER
FIGURE 8E: DETAIL OF TANK OPENING
1000
LTC FRAME
940
TANK OPENING
680
LTC
FRAME
620
TANK
OPENING
17
FIGURE 8F: DETAIL OF PHASE MOLDING EXTENSION INTO TRANSFORMER TANK
FIGURE 8G: DETAIL OF UZD® MOUNTING FLANGE
107
1100
779
Tank and Accessories
A number of flanges exist for a variety of accessories. Flanges that
The BUE drive mechanism is bolted to the bottom of the spring
are not used are provided with a plate steel cover. See Figure 1,
drive compartment after the tap changer tank has been welded to
page 6 for the location and function of these flanges.
the transformer tank. The drive shaft and housing connecting the
BUE to the spring drive compartment can be ordered in several
Flanges are typically raised with tapped holes or untapped holes
lengths, to be specified by the transformer designer, so the BUE
for through bolts. Grooves for recessed O-ring gaskets are located
can be mounted at a convenient height above ground. A bracket
either in the flange or in the device to be mounted on that flange.
on the bottom of the BUE is connected to the tank wall for
Standard accessories include a pressure control relay, a bottom
stabilization if a drive shaft extension is used.
drain valve with sampling port, and outlet and inlet ports plus
internal plumbing for an externally mounted oil filtration system.
Two access panels accommodate entry into the spring drive
The front door is hinged.
mechanism compartment, both of which are fastened with bolts.
Two vents provide ventilation. One vent is located in the bottom
of the compartment near the front, and the other vent is located
The UZD tank is a welded, carbon plate steel enclosure and is
®
supplied with a weld-able flange to facilitate mounting the UZD
®
near the top at the back. The vents are fitted with sintered bronze
tank to the transformer tank. The bottom of the oil-filled switching
filters to prevent insects from entering. Air heated in the BUE
compartment is sloped toward the middle of the tank and also
motor drive can rise up the drive shaft tube housing into the spring
sloped toward the left side of the tank so that all oil flows to the
drive compartment. For ambient temperatures below –40°C, an
drain valve.
extra heater can be provided in the spring drive compartment to
prevent condensation.
18
The UZD® tank is designed to withstand full vacuum to 14.5 psi
Other standard accessories include the following:
positive pressure. Vacuum can be pulled on the transformer
• Bottom drain valve— One inch, flange mounted,
tank with atmospheric pressure in the UZD tank and vacuum
®
globe valve with 3/8” sampling valve
can be pulled on the UZD tank with atmospheric pressure in
• Upper vent hole — One inch with flange and cover
the transformer tank. Bypass piping between the two tanks is
• Pressure switch — United Electric H100 series
not required. Vacuum filling of the UZD oil compartment is
• Magnetic liquid level gauge — Qualitrol, 6 inch 032
®
®
also not required.
series with one form ‘C’ low alarm contact
• Flange for pressure relief device — 6 x 5/8 inch
The tank is not completely filled with oil. The gas space above
the oil serves as expansion space for the oil. The UZD®
has a vent hole in the top center of the tank. This should
be connected to an Auto-Recharging Dehydrating Breather
(ARDB), mounted at eye level, to assure the air entering the
compartment is dry. A dehydrating breather must be used as
diameter holes on 9.25 inch diameter bolt circle
• Flange for Sudden Pressure Relay
• Opening for temperature probe
• Opening for thermal switch
• Mounting provision for heater in Spring Drive Mechanism
high water content in the oil will lead to LTC failure.
A liquid level indicator is included with the UZD® with low level
contacts. SPX Waukesha recommends that alarm contacts be
connected to signal that the transformer should be taken offline should the oil level reach the critical minimum level, thereby
helping to prevent dielectric failures due to low oil level.
A pressure control relay is provided as standard and is
designed to indicate excessive pressure in the tap changer
switching compartment if a fault occurs and then send a
signal to the transformer protective equipment to disconnect
the transformer from the system if there is an unusually high
pressure inside the UZD® tank. Under normal operating
conditions, the switch will operate in less than 5ms. Contacts on
Optional Accessories:
• ARDB2 (Auto-Recharging Dehydrating Breather)
• OF2 Oil Filtration System
• Pressure relief device — Qualitrol series 208
• Option: one form ‘C’ contact with ANSI style connector
• Option: yellow plastic semaphore flag
• Sudden Pressure Relay —Qualitrol series 910 for gas space,
flange mounted, ANSI style connector
• Thermal probe—Transformer manufacturer must provide
gauge, RTD or end use of probe signal
• Thermal switch—Barksdale type MT1H set at –40°C
for mineral oil
this relay are factory set to close at 4.3 psi ±5%. Contacts from
the sudden/rapid pressure rise relay can also be used to trip
the transformer off-line in the event of a fault in the LTC.
The UZD®’s interior and exterior are painted with a two part
epoxy primer. The interior and exterior of the spring drive
and motor drive mechanisms are then top coated with a two
part urethane paint in ANSI 70, sky grey. Upon request, the
outside top coat process can be eliminated, so the transformer
manufacturer can paint with desired paint formula and/or color.
19
B U E M OTO R D R I V E M E C H A N I S M
The BUE motor drive mechanism is designed for outdoor operation
There are two studs welded to the back of the BUE near the top.
of the UZD® Load Tap Changer. Operating temperature range is
One stud has a double hose clamp for securing hoses going to
–40°C (–40°F) to +50°C (122°F).
the Oil Filtration System. The other stud has a single hose clamp
for securing the hose for the ARDB (silica gel breather) typically
The BUE contains all of the equipment necessary to supply
mounted behind and below the BUE. There is a 2” x 3/4” two
mechanical power to the UZD® and provide electrical signalling,
hole ground pad welded to the bottom of the BUE for external
protection and operation. The “90” voltage regulating relay, other
tank grounding.
associated control devices, and power supply circuit breaker are
normally mounted in the main transformer control cabinet and wired
Heater
to the BUE.
There is a 200 w PTC (positive temperature coefficient) anticondensation heater mounted in the BUE. This heater is always
Cabinet
“on” and varies heat output based on ambient temperature;
The BUE cabinet is made of welded sheet steel and treated for
therefore, no thermostat is required. The heater has a fan which
outdoor use. The BUE’s interior and exterior are painted with a
circulates the warmed air around the cabinet.
two part, epoxy primer and then with an ANSI 70, sky grey, two
part urethane top coat. Upon request, the outside top coat process
Gearing
can be eliminated, so the transformer manufacturer can paint with
Referring to Figure 10A, the motor (140) operates via a toothed
desired paint formula and/or color.
belt (101) with a ratio of 5:1, turning operating shaft (105). This
shaft (105) has a bevel gear (102) with a ratio of 5:1, and turns
Referring to Figure 9, the front door is formed as a cap to allow
outgoing shaft (103). Hand crank (104) is applied to operating
access to all parts of the mechanism. The door can be hinged on
shaft (105). Twenty-five revolutions of the hand crank produces five
either the left or right hand side and can be modified at any time.
revolutions of outgoing shaft which is required to complete one tap
Provision is made for padlocking with a maximum 3/8 inch (10 mm)
change operation. The maximum allowable torque on the outgoing
hasp. An inspection window on the front door permits viewing of
shaft is 43.4 ft-lbs. The operating time is approximately 6 seconds
the position indicator, maximum and minimum position drag hand
with an 1150 rpm motor. When viewed from above, the outgoing
indicators, tap change in progress flag and operations counter. The
shaft turns clockwise for a raise operation.
front door and inspection window are sealed with rubber gaskets.
Motor
A horizontal bracket should be provided by the transformer OEM
The standard motor supplied has the following ratings: single-phase,
for attaching the bottom of the BUE cabinet to the transformer
115 volt, 60 Hz, 1150 rpm, 0.2 HP, with automatic reset thermal
tank wall (see Figure 8B for suggested bracket design) when a
overload device to prevent over-heating. The motor is designed for
drive shaft extension is used. A two inch diameter phoenix flange
intermittent duty.
welded in the back of the BUE allows for connection of conduit for
electrical wiring from control box (see Figure 8C for dimensional
See Figure 23, page 37, Contact Timing Diagram for information
location). This opening is plugged for shipment. Two sintered bronze
on when electrical contacts in the BUE open and close during the
filters provide ventilation while also preventing insects from entering.
course of a tap changer operation.
One vent is placed near the front in the bottom of the compartment
and the other near the top at the back of the compartment. An
interior cabinet light is provided and activated with a door switch.
The drive shaft for connection to the UZD® is in the top of the BUE
(see section above on UZD® tank description for more details).
20
FIGURE 9: BUE CABINET
Items are only used with the integrated style oil filter system and not provided when standard external Oil Filtration System (OF2) is used.
21
FIGURE 10A: MOTOR DRIVE MECHANISM – EXPLODED VIEW
22
FIGURE 10B: MOTOR DRIVE MECHANISM
LEG E N D – ITE M S FOR FIG U R E S 10A AN D 10B
1 0 1 ) T I M I N G B E LT
1 1 5 ) CA M D I S K F O R ( 1 3 8 )
1 2 8 ) CA M BA R
102) B EVE L G EAR (LARG E)
116) AR M
1 2 9 ) B R A K E F O R M A I N TA I N I N G C O N TACT
103) COU PLI NG S HAFT
117) B RAKE
1 3 0 ) CA M D I S C F O R 1 3 7
104) HAN D CRAN K
118) B RAKE D I SC
131) D R IVI NG D I SC FOR 130
1 0 5 ) O P E R AT I N G S H A F T
1 1 9 ) F R O N T P L AT E
136) COU NTE R AR M
106) S PU R G EAR (S MALL)
1 2 0 ) O P E R AT I O N C O U N T E R
1 3 7 ) S TA R T C O N TACT S ( 3 3 S )
107) “ON E TU R N” S HAFT
1 2 1 ) P U L L E Y ( M OTO R )
1 3 8 ) M A I N TA I N I N G , I N T E R LO C K I N G ,
1 0 8 ) G E N E VA G E A R D R I V E
122) PU LLEY (G EAR)
109) B EVE L G EAR
123) B EVE L G EAR (S MALL)
1 3 9 ) L I M I T S W I TC H ( L S - 1 A N D L S - 2 )
1 1 0 ) M E C H . P O S . I N D I CATO R
124) S PU R G EAR (LARG E)
1 4 0 ) M OTO R
111) COU PLI NG
1 2 5 ) G E N E VA G E A R
1 4 1 ) I N T E R LO C K S W I TC H
1 1 3 ) M E C H A N I CA L E N D S TO P
1 2 6 ) G E N E VA G E A R
1 1 4 ) B R E A K- O F F S A F E T Y P I N
1 2 7 ) C O N TACT D E V I C E
AU X I L I A RY C O N TACT S
103
115
107
125
102
POSITION
INDICATOR
SHAFT
122
109
104
113
101
114
123
105
121
140
23
Hand Crank
Contact Device
Referencing Figure 10A, the mechanism can be manually operated
Referencing Figure 10A and 10C, shaft (107) is connected to the
by means of a hand crank (104) on the operating shaft (105). The
Geneva gear drive (112) via a coupling (111) and, with a ratio of
direction of operation is shown on an instruction plate where the
36:1, drives a Geneva gear (126) on the shaft of the contact device
hand crank is inserted for manual operation. When the crank handle
(127). The contact device moves 1/36 of a turn, or 10°, per tap
is inserted for manual operation, interlocking switch 84H (141)
change. The Geneva gear drive (112), with its driving pin, will rotate
opens the circuit to the motor contactors, thus preventing electrical
180° in relation to the Geneva gear drive (108).
operation when the crank handle is inserted. A holder bracket for
the crank handle is provided on the inside of the BUE’s door.
Continuation Contact (84C)
The contact device is also supplied with a continuation contact 84C
One-turn Shaft
when the tap changer has two or more positions with the same
Referencing Figure 10A, power from the outgoing shaft drive is
voltage (through-positions). One of these positions is the normal
transferred by means of a cylindrical gear (106) with a ratio of 5:1
position. The through-positions are passed by automatically with
to a spur gear (124) on shaft (107). The shaft therefore rotates one
electrical operation. See description of operation for more detail.
turn for each tap change operation, indexing the Geneva gear (126)
one position for each full revolution of the one-turn shaft per tap
Maintaining Contact
change. The driving pin on the Geneva gear drive (108) will be in
Referencing Figure 10A, cam disc (115) on shaft (107) operates
the slot on the Geneva gear (125) in a normal operating position.
a roller on arm (116) operating the maintaining, interlocking and
auxiliary contacts of device 33 (138). In the raise direction, the
Position Indicator
maintaining contact 33R closes the operating circuit for the motor
Referencing Figure 10A, the Geneva gear (125) operates the
contactor 84R. In the lower direction, the maintaining contact 33L
mechanical position indicator (110) via a bevel gear (109). The
closes the operating circuit for the motor contactor 84L.
position indicator includes two manually resettable drag hand
indicators with a scale on the front plate (119), which is visible
Interlocking Contact
through the window in the door.
Referencing Figure 10A, contact 33-R1 (138) or 33-L1 (138)
opens the operating circuit for the motor contactors. These
Electrical and Mechanical End Stops
contacts act as interlocking contacts if the motor rotation should
Referencing Figure 10A, there are two screws mounted on Geneva
be incorrect due to incorrect phase sequence.
gear (125) at the end of travel positions. As the Geneva gear
rotates to an end position, one of the screws moves Rotary end stop
Auxiliary Contact
(113) which actuates Limit switch LS-1 (139) for the raise direction
Referencing Figure 10A, contacts 33E, 33F, 33G and 33H (137)
or LS-2 (139) for the lower direction. This opens the circuit to the
are auxiliary contacts for providing a signal during a tap
motor contactors and the two circuits of the motor supply. Electrical
change operation.
operation beyond the end positions is thus prevented.
Brake
In the case of faulty limit switches, the motor will be stopped by
Referencing Figure 10A, arm (116) operates a brake (117) through
the mechanical end stop. A slot on the opposite end of rotary end
cam bar (128). The brake is applied to both sides of brake disc
stop (113) will cause the mechanical end stop to rotate so as to
(118). The brake helps ensure the driving mechanism’s outgoing
interfere with a bar cast into the top of bevel gear (102), preventing
shaft stops in the correct position after each tap change operation.
further motion in that direction. The break-off safety pin (114) on
the manual operating shaft’s conical toothed wheel (123) prevents
over-loading of the end stops.
24
FIGURE 10C: MOTOR DRIVE MECHANISM - EXPLODED VIEW
LEG E N D – ITE M S FOR FIG U R E 10C
103) COU PLI NG S HAFT
1 1 9 ) F R O N T P L AT E
131) D R IVI NG D I SC FOR 130
104) HAN D CRAN K
1 2 0 ) O P E R AT I O N C O U N T E R
136) COU NTE R AR M
1 1 0 ) M E C H . P O S . I N D I CATO R
122) PU LLEY (G EAR)
1 3 7 ) S TA R T C O N TACT S ( 3 3 S )
111) COU PLI NG
1 2 5 ) G E N E VA G E A R
1 3 8 ) M A I N TA I N I N G , I N T E R LO C K I N G ,
1 1 2 ) G E N E VA G E A R D R I V E
1 2 6 ) G E N E VA G E A R
1 1 5 ) CA M D I S K F O R ( 1 3 8 )
1 2 7 ) C O N TACT D E V I C E
1 3 9 ) L I M I T S W I TC H ( L S - 1 A N D L S - 2 )
116) AR M
1 2 8 ) CA M BA R
1 4 0 ) M OTO R
117) B RAKE
1 2 9 ) B R A K E F O R M A I N TA I N I N G C O N TACT
118) B RAKE D I SC
1 3 0 ) CA M D I S C F O R 1 3 7
AU X I L I A RY C O N TACT S
25
Indicator Flag
Protection
Referencing Figure 10A, an indicator flag mounted on arm (116) is
Referencing Figure 10C, the motor (140) has an automatic reset,
visible through a slot in the front plate (119). When the mechanism
thermal overload device to help prevent over-heating. The motor is
is on a valid tap position, the flag will be located beneath the area
designed for intermittent duty. Adjustable limit switches, LS-1 (139)
labelled “Position”. During a tap change, the flag is moved to “Raise”
for the maximum raise direction and LS-2 (139) for the maximum
or “Lower”. Indicator flag and front plate are visible through the door
lower direction, are provided to block operation of the mechanism
window.
at end of travel. Mechanical end stops are also provided to prevent
further movement of the mechanism should the end of travel limit
Maintaining Contact Brake
switch fail to operate.
Referencing Figure 10A, a brake (129) with brake blocks
constructed from Bakelite polymer is positioned on cam bar (128)
Over-Current Blocking
outside brake (117). This maintaining contact brake prevents arm
For automatically operated mechanisms, relay equipment provided
(116) from swinging over into the opposite direction when it swings
by the transformer OEM shall include a 50-1 Overcurrent relay to
back to its normal position at the end of a tap change operation thus
prevent tap change operations from being initiated if the current
preventing and additional unwanted tap change operation.
exceeds 1200A (twice the rated current). If an over-current should
occur once the operating sequence has begun, the over-current
Start Contact
relay breaks the operating circuit and the driving mechanism stops.
Referencing Figure 10A through 10C, start contact 33S-1(137) is
operated by cam disc (130) which is freely suspended high up on
If the current decreases, the over-current relay closes and the drive
shaft (107). The cam disc is driven by a pin in driving disc (131),
mechanism continues to the normal position. Note that the contacts
which is fastened to shaft (107). 33S-3 (137) is an extra contact
of the load tap changer are in normal operating position and carry
with the reverse contact function of 33S-1.
current as normal, even if the driving mechanism has stopped in an
intermediate position because of over-current blocking.
Operation Counter
Referencing Figure 10A, a six digit Operation counter (120)
Indication
mounted behind the front plate (119) is driven by arm (136),
Referencing Figure 10C, a mechanical position indicator (110)
registers the total number of tap change operations and is visible
is provided as are manually resettable drag hands for indication
through the door’s window.
of maximum and minimum operating positions. A “tap change in
progress” indicating red flag (116) is also included along with an
Controls
operations counter (120). These four devices are all viewable
Referencing Figure 9, page 21, Local-Remote and Raise-Off-Lower
through the window in the door.
control switches are provided in the BUE. A UZD® equipped with an
optional integrated oil filtration system also includes a filter ON-OFF
reset switch and filter status indicating lights.
26
Wiring and Connections
Optional Accessories
Standard control wiring in the BUE is black, TEFZEL (ETFE)
Several options are available in the BUE motor drive mechanism,
insulation, AWG 12 wire size and rated to 150°C. Wire designation
including
is accomplished with heat shrink wiring sleeves. Terminal blocks
•R
esistance Position Transmitter that closes a contact to add/
for wiring connection are DIN rail mounted, Idec type BHN30W,
subtract a discrete resistor from the circuit
rated for 30 amperes. Wires are terminated at terminal blocks with
•R
esistance Position Transmitter that is a potentiometer
crimped-on ring tongue terminals.
•S
elsyn Position Transmitter
• Incon Position Transmitter
•D
ynamic Ratings Position Transmitter
• Incomplete step alarm contact
•O
dd/even tap position contact
•C
ontacts for step-by-step operation
27
O p e r a t i n g Pr i n c i p l e s
LOA D TA P C H A N G E R
Switching Sequence
The switching sequence is designated as the symmetrical flag cycle, meaning that the main switching contact of the selector switch
“S” (Figures 11-18) breaks after one resistor is positioned in the circuit but before both resistors are positioned in the circuit so that
the circulating current has not yet started to flow. This ensures maximum reliability when the switch operates with overloads.
With the transformer carrying load, the breaking takes place at the first current zero after contact separation, equating to an average
arcing time of approximately 5–6 milliseconds at 60 Hz. The total time for a complete sequence of movement of the selector switch
after the spring battery discharges is approximately 70 milliseconds. The time for the motor drive mechanism to wind up the spring
battery in the spring drive mechanism to the point of discharge and get to position for the next tap change operation is approximately
6 seconds.
Arcing Tap Switch (Tap Selector Switch)
The switching sequence, when switching from stationary contact position D1 to stationary contact position D2, is shown in the series
of Figures 11–18.
FIGURE 11
FIGURE 12
L E G E N D – C O N TACT S F O R F I G U R E 1 1
Starting at rest on stationary contact D1, the main current carrying
contact I carries the load current to the commutator hub. The
transition arcing roller contacts H1 and H2 are open, resting in the
spaces between the fixed contacts. No current is flowing through
the transition resistors R1 or R2.
R ) T R A N S I T I O N R E S I S TO R ( R 1 A N D R 2 )
D ) S TAT I O N A RY C O N TACT ( D 1 TO D 1 8 )
H 1 / H 2 ) T R A N S I T I O N A R C I N G R O L L E R C O N TACT
I ) M OV I N G M A I N C U R R E N T CA R RY I N G C O N TACT
S ) M OV I N G M A I N S W I TC H I N G A R C I N G R O L L E R C O N TACT
C ) C O M M U TATO R H U B
 C U R R E N T F LOW
28
FIGURE 13
Transition arcing roller contact H1 makes with stationary
contact D1. Transition resistor R1 is now carrying a small
amount of current but most of the through current is still
flowing through moving main current carrying contact I.
FIGURE 14
Main current carrying contact I breaks with stationary contact
D1. The moving main switching arcing roller contact S breaks
with stationary contact D1. At this point, all through current
is carried by transition arcing roller contact H1 and transition
resistor R1.
FIGURE 15
Transition arcing roller contact H2 makes with stationary
contact D2. The through current is split between the
transition contacts H1 and H2. The circulating current is
now established and is driven by the step voltage between
contacts D1 and D2 and limited by transition resistors R1 and
R2 in series to the circulating current. The circulating current
could be adding to or subtracting from the through current.
29
FIGURE 16
Transition arcing roller contact H1 breaks from stationary contact D1. At
this point, all through current is carried by transition arcing roller contact H2
through transition resistor R2. The circulating current path is broken.
FIGURE 17
Moving main arcing roller switching contact S makes with stationary
contact D2 and carries the through current. The moving main current
carrying contact makes with stationary contact D2 and carries the through
current, while a small portion of the current is carried by transition resistor
arcing roller contact H2 through transition resistor R2.
FIGURE 18
Transition arcing roller contact H2 breaks with stationary contact D2.
Main current carrying contact I is now carrying all the through current.
The tap change is complete and the selector switch is at rest on stationary
contact D2.
30
Reversing Change-Over Selector
for Plus/Minus Switching (Figures 19A, B and C, page 32)
If a lower command is received, the selector switch will reverse
This device also called a reversing switch, is used to change the
moving contact arm R travels from contact 17 to contact 1 while
polarity of the regulating winding 180° with respect to the winding
the spring battery is being charged to move the selector switch
being regulated. This allows double duty of the contacts on the
from N/neutral (contact number 18 on phase molding) to RN/
selector switch, i.e. each stationary contact can be used twice,
raise neutral (contact number 1 on phase molding). This turns the
once in the raise direction and again in the lower direction.
winding direction, or polarity, of the regulating winding 180° with
the above movements. However, if a raise command is received,
respect to the main winding being regulated. Continuation contact
When a raise command is received with the selector switch in 1L
84C remains closed and initiates a second tap change operation
(contact number 16 on phase molding), the selector switch moves
which moves the selector switch from RN to 1R position (contact
to LN, or lower neutral (contact 17 on phase molding, a through
number 2 on phase molding).
position) and then continues on to N, or neutral (contact 18 on
phase molding). The contact arm of the selector switch makes two
Through-Positions
tap change operations on either side of neutral without stopping
Contact positions LN and RN mentioned above are termed
(through positions). This operation is programmed into the BUE
‘through-positions’ since the tap changer is programmed to
Motor Drive Mechanism via continuation contact 84C (see contact
automatically step through these locations. If the tap changer is
timing diagram below).
set up to use less than 33 positions, some of the selector switch’s
fixed contacts are connected to the same tap of the regulating
At N/neutral, moving contact R carries no current. The two
winding. Therefore, several more through-positions occur. When
stationary reversing switch contacts are connected to the adjacent
the motor drive mechanism is initiated electrically (as opposed to
selector switch contacts, 1 and 17, by copper rods internal to
manual hand cranking), it will automatically pass those ‘through-
the epoxy phase molding. The load current travels from the main
positions’ and stop in the ‘normal position’.
winding being regulated, through N (contact number 18 on phase
molding) and out through the selector arm’s center contact (19 or
0 on the phase molding. The regulating winding’s top end remains
connected to the main winding. The tap changer stays in this
position until another raise or lower command is received.
31
FIGURE 19A: SWITCHING SEQUENCE — STAGE 1
Wiping action on a stationary contact where
the moving contact is “on”.
R
LN
N
RN
IR
IL
19
FIGURE 19B: SWITCHING SEQUENCE — STAGE 2
Moving contact switches from one stationary
contact to other stationary contact.
19
FIGURE 19C: SWITCHING SEQUENCE — STAGE 3
Moving contact wipes the stationary contact
to final position.
19
32
Schematic Diagram
See Figure 20A-C for transformers with and without a series transformer:
FIGURE 20A: LTC AND TRANSFORMER WINDING CONNECTIONS
FIGURE 20C: LTC AND TRANSFORMER WINDING CONNECTIONS
WITH SERIES TRANSFORMER
WITH AUTO CONNECTED SERIES TRANSFORMER
H1
MAIN TRANSFORMER
HV
17
15 13 11 9 7 5 3
1
16 14 12 10 8 6 4 2
LV
16
15
14
13
12
11
9
10
8
7
6
5
4
3
1
2
RV
17
1
19
X0 AUTO CONNECTED
18
1
IS
FIGURE 20D: CONNECTION DIAGRAM
2 WINDING
X0 SERIES TRANSFORMER
H1
FIGURE 20B: LTC AND TRANSFORMER WINDING
TRANSFORMER
WITHOUTMAIN
SERIES
TRANSFORMER
14
13
12
11
10
M1
9
H
8
7
6
5
4
3
2
M2
18
17
R
1
19
R
H
CONNECTS CONNECTS
RAISE LOWER
1
1-19
2
2-19
3
3-19
4
4-19
5
5-19
CONNECTIONS
6
6-19
7
7-19
8
8-19
9
9-19
18-17
18-17
10
10-19
11
11-19
12
12-19
13
13-19
14
14-19
15-19
15
16-19
16
17-19
17A
18-19
17
1-19
17B
2-19
18
3-19
19
4-19
20
5-19
21
6-19
22
7-19
23
8-19
24
18-1
18-1
9-19
25
10-19
26
11-19
27
12-19
28
13-19
29
14-19
30
15-19
31
16-19
32
17-19
33
19
X1
1
X1
POSITION
1
W/0 SERIES TRANSFORMER
X0
18
18
17
17
1
M1
R
19
15
X1
SERIES TRANSFORMER
17
16
R
M2
18
IL
17
H
M2
17
M1
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
M OTO R D R I V E M E C H A N I S M
TAP CHANGER IN NEUTRAL POSITION N
NOTE: S
ome older phase moldings may not have any terminal numbers next to terminals.
Newer moldings may show a “0” (zero) for the terminal shown as 19 on the
Connection Diagram. Terminal 0 and 19 are the same. If the phase molding does
not have a terminal 19 as shown in the Connection Diagram, make connection to
the terminal marked 0 on the phase molding.
Operational Description - Schematic
The motor drive mechanism provides the motive force that makes
(43T-3), a Lower-Off-Raise selector switch (43T-1), a voltage
the tap changer operate. The force is provided by a motor through
regulating relay with output contacts for raising and lowering the
a series of gears and on to a drive shaft to transmit the energy to
load tap changer (90R and 90L), an over current relay (50-1),
the spring drive mechanism. Several features are incorporated to
motor contactors (84R and 84L), limit switches (LS-1 and LS-2)
promote long service intervals and reliability.
and interlocks. Figure 21 shows these features on a typical Control
Schematic. The voltage regulating relay (90) and the over current
The basic tap changer control circuit consists of a Local-Remote
relay (50-1) are provided by the transformer OEM in the transformer
selector switch (43T-2), a Manual-Automatic selector switch
control cabinet.
33
8
7
6
FIGURE 21: CONTROL SCHEMATIC (SHOWN WITH OPTIONAL INTEGRATED OIL FILTRATION SYSTEM)
5
Timer T-1 and connected devices are included for optional integrated oil filtration system. These items are located in external OF2 oil filter as standard.
LS
7-1
L
LS
DM501
4-1
D
LS
8-1
N
LS
DM502
3-1
84R
7-2
1
4-2
1
8-2
3
3-2
3
84L
84R
84L
1
2
2
BK
C
R
84M
2
W
GND
4
4
DM517
DM516
43T-1
L
33
RAISE
DM515
3
4
7
43T-1
L1
LS
8
5-1
LOWER
1
DM522
3
1
C
1
1
DM526
5
ON
3
200W
BK
4
L
DM 534
LTS
C
B
N
DM 536
L
DM 537
N
DM 562
1
33
L
R1
84R
53
A1
A2
84
54
2
2
84L
2
53
71
6
84H
84R
LS
1-1
54
21
DM513 L
22
DM514
72
84L
84R
61
1-2
62
A1
DM521 N
A2
CUSTOMER TO SUP
AND ACCESSORIES.
W
+t°
5°C
M
DM 533
33S
84R
62
HTR
43HS
DM 531
N
R 4
84C
33
DM527
L
83
33
2
84R
84L
61
5-2
+t°
71Q-1
LT
B
NC
B
S
33
E
DM 539
10
33
DM 540
11
F
DM 541
12
33
DM 542
15
G
DM 543
16
33
DM 544
13
H
DM 545
14
LS
DM 546
MAX RAISE LIMIT
DM 547
6-4
6-1
6-2
LS
DM 549
MAX LOWER LIMIT
DM 550
2-4
2-1
2-2
CONFIDENTIAL AND PROPRIETARY
This document contains proprietary information of Waukesha Electric Systems, Inc. (hereafter WES) and may not be disclosed, copied, modified, or used without permission of WES.
If WES has authorized your possession and/or use of this document, then WES has granted you a limited, revocable license to use this document and the information in it only for purposes specified by WES.
The document must be promptly returned to WES after its use and/or upon demand by WES. Any posession, disclosure, copying, modification, or use not authorized by WES can constitute a violation of applicable law and be subject to severe penalties.
Copyright © 2013 Waukesha Electric Systems, Inc. All Rights Reserved.
34
R
CONNECT TO LIQUID
QUALITROL ANSI 3 CO
9
DM 551
BK
3
CO
DM 538
DM 548
LOW
2
S
G
A
1
FIGURE 22: CONTROL SCHEMATIC – DEVICE LEGENDS
DRIVE MECHANISM
DEVICE NO. DESCRIPTION
33
MAINTAINING CONTACT
33S
STARTING CONTACT
33SPT
SYNCHRO POSITION TRANSMITTER
43T-1
LTC LOWER-OFF-RAISE SWITCH
84C/33N
CONTINUATION CONTACT W/CLOSED NEUTRAL
84H
HAND CRANK LOCKOUT SWITCH
84L
MOTOR CONTACTOR, LOWER
C1
CAPACITOR
CO-2
CONVENIENCE OUTLET
125V, 20A
H-3
HEATER ASSEMBLY
200W, 120VAC
HS-2
HEATER SWITCH, OFF-ON
2 POS., 1NO – 1NC
LS
LIMIT SWITCH
LT-3
CABINET LIGHT
LTS-2
DOOR OPERATED LIGHT SWITCH
HS-2
CONTACTS
1
2
3
4
X - CLOSED CONTACT
43T-1
CONTACTS
1
2
3
4
X - CLOSED CONTACT
PIN
1-2
3-4
POSITION
OFF
ON
X
X
(SPRING RETURN TO CENTER)
POSITION
PIN
LOWER
OFF
RAISE
1-2
X
3-4
X
35
Contact Timing Diagram
The raise and lower operation diagrams illustrate contact operating
The motor starts and drives the mechanism in the lower direction.
sequences for one tap change operation equal to 25 turns of the
Maintaining contact 33L closes and holds contactor 84L. At the
hand crank shown across the top of the diagram. The lower three
same time, the mechanical brake (117, Figure 10A) is released.
diagrams demonstrate the contact sequence for the electrical limit
Then start contact 33S-1 opens. Contact 33L is closed until just
switches and the continuation contact for the through-positions.
before the tap change is completed, then it breaks, the contact
is released, the motor is disconnected and the brake begins to
Local Control
operate. Start contact 33S-1 closes again. The brake stops the
The mechanism can be operated by control switch 43T-1 “Lower-
driving mechanism and the tap change is complete.
Off-Raise”. To operate the tap changer manually, 43T-2 should be in
the “Local” position, and 43T-3 should be in the “Manual” position.
Remote Control
To operate the tap changer by remote control, control selector
S E Q U E N C E O F E V E N T S F O R A R A I S E O P E R AT I O N I S A S F O L LOW S :
switch 43T-2 must be in the “Remote” position. A terminal in the
When the 43T-1 Lower-Off-Raise switch is operated in the Raise
motor drive cabinet supplies control voltage for the remote push
position, raise relay 84R becomes energized . The contactor closes
buttons. Incoming control circuits for raise and lower impulses
and is held by start contact 33S-1 and its own holding contact. The
connect to other terminals as shown in the schematic diagram
raise relay 84R interlocks with a normally closed contact of the
Figure 21, page 34. Local operation is not possible when switch
lower contactor 84L, a limit switch LS-1 that opens at the maximum
43T-2 is in the “Remote” position, and remote operation is not
tap changer operating position 16R and an interlock switch 33L-1
possible when in the “Local” position.
which opens when the operating shaft rotates in the direction that
produces a decrease in the tap changer operating position.
Automatic Operation Local Mode
To operate the tap changer automatically, 43T-2 must be in the
The motor starts and drives the mechanism in the raise direction.
“Local” position and 43T-3 in the “Automatic” position. The tap
Maintaining contact 33R closes and holds contactor 84R. At the
changer can now be operated by the “90” voltage regulating relay.
same time the mechanical brake (117, Figure 10A) is released.
The “90” relay compares the 120 volt signal from a potential
Then start contact 33S-1 opens. Contact 33-R is closed until just
transformer on the bus to be regulated, to the adjustable “set value”
before the tap change is completed, then it breaks, the contact
reference voltage in the “90” relay to determine if a tap change is
is released, the motor is disconnected and the brake begins to
required and, if so, in which direction. The bus voltage signal must
operate. Start contact 33S-1 closes again. The brake stops the
be outside the adjustable “bandwidth” setting of the “90” relay and
driving mechanism and the tap change is complete.
for a length of time longer than the adjustable “time delay” setting of
the “90” relay for a tap change operation to be initiated. If voltage
S E Q U E N C E O F E V E N T S F O R A LOW E R O P E R AT I O N :
drops below the lower voltage limit and remains below the lower
A similar operation cycle is obtained, but in the lower direction,
limit for the duration of the time delay setting, a raise tap change
when the control switch 43T-1 is switched to the Lower position
operation will be initiated by energizing the raise output relay 90R.
which energizes the lower relay 84L. The contactor closes and is
This initiation operation also energizes the raise relay 84R. The
held by start contact 33S-1 and its own holding contact. The lower
raise output relay remains energized until the tap changer operation
relay 84L is interlocked through a normally closed contact of the
raises the voltage to a value above the lower limit of the bandwidth
raise relay 84R, a limit switch LS-2 that opens at the minimum tap
which is then maintained to assure a complete operating cycle as
changer operating position 16L, and an interlock switch 33R-1 that
described earlier for manual operation.
opens when the shaft operates in a direction which produces an
increase in the tap changer operating position.
Similarly, if the bus voltage is too high, the above process repeats
but in the lower direction.
36
Over-current Relay
An over current relay “50-1” shall be provided in the seal-in circuit
to prevent the tap changer from operating when the load current is
excessive such as during a short circuit. The 50-1 is adjustable from one
to two times full load current.
The 90 and 50-1 relays are
supplied by the transformer
manufacturer and typically
Through-Positions
The UZD® load tap changer operates automatically in two positions: one
labelled raise neutral/RN and the other labelled lower neutral/LN. Each
of these positions includes a connection that produces the same voltage
as neutral. A continuation contact 84C is closed when the tap changer
mounted in the main
transformer control box.
is in one of these two positions, as can be seen in the Contact Timing
diagram Figure 23. This closure causes the mechanism to make an
additional tap change operation to prepare for the reversing change-over
selector to operate without current flow.
When operating over a through-position in the raise direction, maintaining
contact 33R is bridged by continuation contact 84C via a contact on
motor contactor 84R (raise). Contactor 84R remains energized, causing
FIGURE 23: CONTACT TIMING DIAGRAM
the mechanism to automatically carry out a second raise operation.
When operating over a through-position in the lower direction, maintaining
contact 33L is bridged by continuation contact 84C via a contact on
motor contactor 84R. Motor contactor 84L (lower) remains energized
and the mechanism automatically carries out a second lower operation.
If the motor power supply opens and then recloses in a through-position,
only the motor contactor 84L will be energized. The mechanism then
moves in the lower direction to a normal position.
With manual hand crank operation, the mechanism must be put into a
‘normal’ position. If the mechanism is left between two positions or in a
through-position, the mechanism starts immediately upon removal of the
hand crank.
Step-by-Step Operation
Step-by-step operation is an optional feature only used in the manual
mode. The UZD® will make tap change operations continually if the raise
or lower switch is held. In step-by-step operation, only one tap change
will be made until the raise or lower switch has been released. When the
raise or lower switch is operated again, one more tap change will occur.
Upon request, a relay 84S will be provided in the BUE cabinet to perform
this function.
37
Te ch n i c a l D a t a a n d C h a r a c t e r i s t i c s
R AT I N G S – I N S U L AT I O N L E V E L
TABLE 1: ELECTRICAL RATINGS
38
1
TA P C H A N G E R D E S I G N AT I O N
UZ D RT 200/600
2
M A X I M U M R AT E D T H R O U G H C U R R E N T
600 AM PS
3
R E L E VA N T R AT E D S T E P VO LTAG E AT M A X I M U M R AT E D T H R O U G H
CU R R E NT OF 600 AM PS
6 0 0 VO LT S
4
M A X I M U M S T E P VO LTAG E AT R AT E D T H R O U G H C U R R E N T O F 2 0 0
AM PS
1 2 0 0 VO LT S
5
S H O R T C I R C U I T W I T H S TA N D CA PA B I L I T Y
(PEAK / R M S) 2 S ECON D S
30 kA/12kA
6
NOMINAL SYSTEM OPERATING VOLTAGE
34.5 kV
7
HIGHEST OPERATING SYSTEM VOLTAGE
34.5 kV
8
INSULATION BETWEEN ALL LIVE PARTS TO
GROUND AND BETWEEN PHASES, FOR CONTINUOUS
VOLTAGE OPERATION
34.5 kV
9
D I E L E CT R I C W I T H S TA N D I M P U L S E O F 1 . 2 X 5 0
M I C R O S E C O N D S N E G AT I V E A N D P O S I T I V E
P O L A R I T Y A N D AC ( 1 M I N U T E F O R 6 0 H Z )
I M PU LS E KV
PEAK
AC
KV
Live Parts to Ground
200
70
Between Adjacent Phases
200
70
Between First and Last Contacts
200
60
Between Adjacent Contacts
60
24
10
M A X I M U M N U M B E R O F S E R V I C E TA P P O S I T I O N S
33
11
M A X I M U M N U M B E R O F I N H E R E N T TA P P O S I T I O N S
35
12
R E G U L AT I N G S C H E M E
R EVE R S I NG
(PLUS-M I N US)
13
N U M B E R O F TA P S I N T H E R E G U L AT I N G W I N D I N G
16
14
M A X I M U M S E R V I C E VO LTAG E AC R O S S R E G U L AT I N G W I N D I N G
10 kV at 600A
20kV at 200A
TRAN S ITION TI M E
The BUE motor drive mechanism needs approximately six seconds
Design tests included the following:
to complete 25 revolutions of its output drive shaft to make one
• Temperature rise of contacts
tap change operation. The output drive shaft from the BUE stores
• Switching
energy by tensioning springs in the spring drive mechanism. Once
• Short-circuit current
the spring operator crank passes top dead center and the springs
• Transition impedance
discharge, the selector switch takes approximately 70 milliseconds
• Mechanical
to complete one tap change operation. Arcing time of approximately
• Dielectric
six milliseconds occurs during the 70 millisecond selector switch
Routine tests performed on each UZD® tap changer include:
transition time.
• Proper assembly verification
S TA N DA R D S A N D T E S T I N G
• Mechanical test
Design tests were performed and passed to verify the UZD ’s ability
• Auxiliary circuits insulation test
to meet the specified requirements in IEEE C57.131-1995 and IEC
• Final inspection
®
60214. Copies of design test reports are available upon request.
R AT I N G P L AT E
FIGURE 25: UZD® LTC NAME PLATE
FIGURE 26: MOTOR DRIVE NAME PLATE
140
[ 5.51 ]
140
[ 5.51 ]
130
[ 5.12 ]
130
[ 5.12 ]
5
[ 0.20 ]
5
[ 0.20 ]
5
[ 0.20 ]
5
[ 0.20 ]
5
[ 0.20 ]
UZDRT
150
[ 5.91 ]
150
[ 5.91 ]
160
[ 6.30 ]
160
[ 6.30 ]
39
S T E P VO LTAG E A N D T H R O U G H - C U R R E N T
assumes a 67% average load factor. Electrical contact life should
The maximum allowable step voltage is limited by the electrical
never be assumed higher than 500,000 operations, although higher
strength and switching capacity of the selector switch and is,
contact life may be possible.
27 (step voltage/y axis vs. rated through-current/x axis) below. The
rated through-current of the tap changer is the continuous current
which the tap changer is capable of transferring from one tap to the
next at the relevant rated step voltage.
The rated through-current and step voltage are used to select the
transition resistor value in order to minimize arcing and maximize
contact life. The rated through-current adjusted by the turns
ratio of the series transformer (if applicable) helps determine
the contact life.
To determine the interval between inspections, divide the estimated
contact life by five.
FIGURE 28: PREDICTED CONTACT LIFE WITH BREAKING CURRENTS
N U M B E R O F O P E R AT I O N S x 1 0 3
therefore, a function of the rated through-current as shown in Figure
500
400
300
200
100
0
0
FIGURE 27: STEP VOLTAGE VS. RATED THROUGH-CURRENT
100
400
500
600
A
TABLE 2: ESTIMATED CONTACT LIFE
1200
S T E P VO LTAG E
(V)
300
TH ROUG H CU R R E NT (AM PS)
V
A L L TA P C H A N G E
O P E R AT I O N S M A D E
AT M A X I M U M
N A M E P L AT E R AT I N G
1000
800
600
400
200
0
0
100
200
300
400
500
600
A
R AT E D T H R O U G H C U R R E N T
(A)
M E C H A N I CA L L I F E
SPX Waukesha’s UZD® load tap changer was tested to over
a million operations based on Mechanical Endurance Test
requirements. No mechanical failure occurred during testing nor
did the components wear in ways which prevented the tap changer
from functioning at the end of the test.
C O N TACT L I F E
Predicted contact life of the selector switches’ fixed and moving
contacts is shown in Figure 28. The UZD contact life curve shown
ASSUMING A
0.8 LOAD FACTOR
ASSUMING A
0.67 LOAD FACTOR
Through
Current
Contact
Life
Through
Current
Contact
Life
Through
Current
Contact
Life
<250 Amps
500,000
<250 Amps
500,000
<250 Amps
500,000
262.5
487,500
262.5
500,000
262.5
500,000
275
450,000
275
500,000
275
500,000
287.5
425,000
287.5
500,000
287.5
500,000
300
400,000
300
500,000
300
500,000
312.5
383,300
312.5
479,125
312.5
500,000
325
372,200
325
465,250
325
500,000
337.5
351,000
337.5
438,750
337.5
500,000
350
338,900
350
423,625
350
500,000
362.5
327,800
362.5
409,750
362.5
489,254
375
316,700
375
395,875
375
472,687
387.5
305,600
387.5
382,000
387.5
456,119
400
294,500
400
368,125
400
439,552
412.5
288,900
412.5
361,125
412.5
431,194
425
277,800
425
347,250
425
414,627
437.5
266,700
437.5
333,375
437.5
398,060
450
255,600
450
319,500
450
381,493
462.5
250,000
462.5
312,500
462.5
373,134
475
244,400
475
305,500
475
364,776
assumes that all tap change operations are made at the maximum
487.5
236,100
487.5
295,125
487.5
352,388
rating; however, transformers are rarely loaded to maximum rating.
500
227,800
500
284,750
500
340,000
512.5
220,000
512.5
275,000
512.5
328,358
525
211,100
525
263,875
525
315,075
537.5
205,600
537.5
257,000
537.5
306,866
550
200,000
550
250,000
550
298,507
562.5
194,400
562.5
243,000
562.5
290,149
575
188,900
575
236,125
575
281,940
587.5
186,100
587.5
232,625
587.5
277,761
600
183,300
600
229,125
600
273,582
Estimated contact life can be calculated by dividing the estimated
contact life at maximum rating by an assumed load factor. In Table
2, the middle column assumes an average load on a transformer
of 80% of the maximum nameplate rating. The right hand column
40
200
R E V E R S E P OW E R F LOW
M I N E RAL OI L/ FR3 FLU I D
The UZD® operates on a symmetrical flag cycle, and, as such,
O P E R AT I N G T E M P E R AT U R E S
arcing is the same for either current direction; therefore, reverse
Tests conducted verify that the UZD® will operate in mineral oil at
power flow should have no adverse effect on the UZD®. However,
–25°C with no noticeable change in timing, will operate at –40°C
operating in reverse power flow mode is typically considered
with an acceptable 25% increase in timing, and may be operated at
undesirable for step-down transformers as a voltage signal input
–50°C in a de-energized mode. Switching overload currents when
to the regulating relay is not usually present from the HV bus and
the mineral oil is between –25°C to –40°C is not recommended.
is a requirement for this to work properly. In most of these cases,
therefore, the regulating relays sense reverse power flow and block
Additional tests verify that the UZD® will operate in FR3 fluid at
operation of the LTC.
–15°C with no noticeable change in timing. A thermo-switch can
be mounted in the bottom of the UZD® oil-filled compartment and
S HORT CI RCU IT STR E NGTH
connected to disable the motor drive circuit and prevent operation
Tests conducted on the UZD® verify its ability to withstand 12,000
of the tap changer should the FR3 fluid temperature drop below
Amps for an equivalent two second time with a 30,000 Amps peak
–10°C. A heater circuit is in development to prevent the FR3 fluid
asymmetrical offset at the beginning of the test. These values
from going below –10°C even after the FR3 fluid has cooled to
are 20 times rated current, twice the amount required by IEEE
temperatures as low as –40°C. If the UZD® will be filled with natural
C57.131-1995.
ester fluid, SPX Waukesha recommends that a Nitrogen Generator
be used to bleed a small amount of nitrogen across the gas space
LOA D I N G B E YO N D N A M E P L AT E
in the UZD® to 1) sweep away arcing gasses generated, and 2)
If the maximum rated current of the regulating winding is less than
exclude oxygen and water vapor from entering the UZD® gas
the rated through-current of the UZD®, the UZD® will not restrict
space. Contact SPX Waukesha for further information about this
occasional operation beyond nameplate rating of the transformer,
arrangement.
in accordance with IEEE C57.91, CAN/CSA-C88-M90 and IEC
60354 as noted below:
Operation at fluid temperatures up to +80°C is permitted in either
mineral oil or FR3 fluid.
While carrying 1.2 times maximum rated through-current
continuously, tests shall be performed to verify that the steady-state
T I E - I N R E S I S TO R S
temperature rise of the contacts does not exceed 20°C above the
During switching of the change-over selector switch, the regulating
temperature of the insulating fluid surrounding the contacts.
winding will be disconnected from the main winding and capacitively
- IEEE C57.131-1995, Paragraph 6.1.1: LTCs that comply with
charged from the adjacent winding. If this voltage gets too high, the
the above definition of maximum rated through-current, and
change-over selector switch contacts cannot break the capacitive
when installed and properly applied in a transformer or regulating
current, whereby the regulating winding is short-circuited causing
transformer, can be loaded in accordance with the applicable ANSI
possible damage to the transformer.
or IEEE loading guide. Per IEEE C57.131-1995, Paragraph 6.1.2
Recovery voltage should be calculated and limited to a maximum
Tests conducted on a Waukesha® UZD® verify that all contact
of 20 kV if through current is limited to 200A or less or a maximum
temperature rises meet the above requirements. Additional tests
of 10kV if through current is greater than 200A. See Figure 27:
were conducted at 1.5 and 2.0 times maximum rated through-
Step Volaage vs. Rated Through-Current. The usual method to limit
current to further verify the UZD ’s ability to carry currents which
recovery voltage is by means of a high-resistance, tie-in (sometimes
might occur if a transformer were loaded beyond nameplate rating
called a “damping”) resistor. The tie-in resistor is continuously
per ANSI/IEEE C57.91.
connected between the midpoint of the regulating winding and the
®
main winding. Values for this resistor typically range from 50 kΩ
41
to 500 kΩ. As this resistor remains continuously in the circuit, the
to have ambient temperatures below –25°C then the optional
losses from this resistor should be reported in the no-load losses
200w/400w heater should be specified. With this heater, the BUE
of the transformer. These high voltages are typically found in
can operate down to temperatures of –50°C. Shielding the BUE
windings above 100 kV line-to-line for the terminal being regulated
motor drive compartment from direct sunlight is required when
with a UZD . All autotransformers should be checked for high
ambient air temperatures are above +60°C.
®
recovery voltage.
Contact your SPX Waukesha channel partner if you need
assistance with this calculation.
30°C over the surrounding oil temperature. Conductors must be
During the six seconds that the BUE motor drive is operating during
a tap change, the sound level at one foot from the UZD®/BUE is
an average 68 db(a) with a 0.4 second spike to 85 db(a) when the
spring battery discharges. At five feet from the UZD®/BUE the
sound level is 60 db(a) with a 0.4 second, 75 db(a) spike. While
not making a tap change, there should be essentially no sound
generated by the device.
appropriately sized to limit the temperature.
G ROU N D I NG
If the UZD® is to be grounded, a cable lug described below should
be connected to terminal 17 on the transformer side of the UZD®
and connected via cable to a ground point somewhere in the
transformer tank. A convenient place for these grounds would be
on a stud welded to the tank wall in the area of the tank opening to
accept the UZD®. There will be one cable per phase.
O P E R AT I O N AT LOW E R A N D H I G H E R
CA B L E L U G S
A M B I E N T A I R T E M P E R AT U R E
The BUE motor drive mechanism will operate in ambient air
temperatures from –50°C to +60°C. The compartment is heated
with a Positive Temperature Coefficient (PTC) heater rated 200w.
This positive temperature heater changes resistance with air
temperature so its resistance goes up as the air temperature goes
up and less current is passed, generating less heat. The reverse is
true for lower temperatures. No thermostat is required as the heater
is always on with varying output in relation to required heat.
The standard heater in the BUE is rated at 200w and is suitable
for ambient air temperatures down to –25°C. Where it is expected
42
The temperature of the conductors connected to the terminals on
the back of the UZD® in the main transformer tank must not exceed
SOU N D LEVE L
FIGURE 29: SMALL CABLE LUG, 1 AWG
C O N D U CTO R S F R O M W I N D I N G S
Special cable lugs are connected to the stranded copper conductors
coming from the windings. The cables must be crimp connected to
these cable lugs. SPX Waukesha will provide the correct number
of required lugs. Cables must be one of the following sizes and
specified with UZD® order:
TABLE 3: AVAILABLE CABLE LUG SIZES
CA B L E A R E A
(mm2)
AWG
50
1
11
29
95
4/0
15
30
150
300MCM
19
31
FIGURE 30: MEDIUM CABLE LUG, 4/0 AWG
HOLE DIAMETER
(mm)
SEE FIGURE
FIGURE 31: LARGE CABLE LUG, 300 MCM
A s s e m b l y t o Tr a n s f o r m e r & C o m m i s s i o n i n g
R E C E I V I N G I N S P E CT I O N
Unpacking
Moisture Evaluation
Upon receipt of a UZD®, inspect the packaging for signs of damage.
If the packing material seems wet (i.e. plastic is coated with
For domestic shipments, remove the wooden cover protecting
moisture), the tap changer must be dried out before being mounted
the contacts on the back of the UZD® and also the wooden cover
to the transformer. This can be accomplished in most cases by
protecting the pressure switch on the end of the UZD®. Remove
blowing hot air on the device (air temperature should not exceed
banding, plastic and cardboard protectors from the BUE. For
90°C). Applying pressure or vacuum is not necessary at this time.
international shipments open the cover of the transport box and
remove all shipping materials. UZD® and BUE can be left on the
See below for instructions if tap changer will not be installed
skid until mounted to the transformer.
immediately upon receipt.
Temporary Storage Before Assembly
The UZD® oil compartment is purged with
If the UZD® will not be installed upon receipt, perform the receiving
dry nitrogen at 5 psi prior to shipment. This
inspection as outlined above, verify the tap changer is approved for
pressure should be relieved prior to attempting
use and then store it in a warm, dry location until ready for assembly.
to open the oil compartment at any opening.
Lift the handle on the small brass pop off
The tap changer oil compartment is filled with dry nitrogen
pressure relief valve on the cover of the UZD®
under 5 psi positive pressure prior to shipping. If this valve is
to relieve this pressure.
operated manually and there is no pressure, refill with dry air or
dry nitrogen and perform a leak test. If the tap changer is opened
and the nitrogen fill is lost and the UZD® will not be installed on a
Product Verification
transformer immediately, the tap changer oil compartment must be
Confirm that the serial number, description and quantity match
purged and filled with dry nitrogen at a pressure not exceeding 5 psi
the shipping documents, including the packing list and order
before being stored in a heated building/enclosure.
acknowledgement. The serial number can be found on the
nameplate on the outside of the device.
The UZD® and BUE are not packaged for storage outdoors or in an
unheated building. To store in these conditions, the following steps
Damage Inspection
should be taken:
Inspect the UZD® and BUE for visible signs of damage that may
1) Fill and seal the UZD® with dry nitrogen at maximum 5 psi
have occurred during shipment due to rough handling, including
2) Provide weather protection for the exterior of the tank and
a search inside the BUE. If shipping damage is found that could
cause the tap changer to function improperly, a damage report
terminal boards (particularly the bare steel weld flange)
3) Energize built-in space heaters in the BUE
should be completed and sent to the freight carrier, freight
forwarder and/or your insurance company. Photographs should be
taken of the damaged areas, marked with the serial number of the
tap changer and sent to SPX Waukesha for analysis and comment.
Contact your SPX Waukesha Channel Partner for further discussion
and disposition of any issues.
43
P R E PA R AT I O N
To properly align the tap changer on the tank for welding, use the following procedure:
•L
ocate fit-up hooks on tap changer tank frame (“H” frame) — see Figure 32.
• Position the tap changer “lip” on hooks.
• Check level of spring drive bottom plate.
•S
him on hooks to improve level condition. Shims should be less than the depth of the notch in the
fit-up hook.
• Tack weld tap changer tightly to tank frame.
•T
ap changer attaching lip must be tack welded tight against frame before finish welding.
WE LD I NG
(Figure 33) All welding should be done with G.M.A.W. (Mig) using .045” ER70S-6 wire and 95%
Argon - 5% oxygen shielding gas at approximately 250 amps and 25 volts. If welding will be done in
an area where smoke and contamination are not an issue, then 70 tensile flux core wire can be used.
Overhead and horizontal welding shall be done with a straight, uninterrupted stringer bead. The arc
should be directed into the joint at an angle of approximately 45º.
Vertical welding with G.M.A.W. (Mig) shall be completed in an upward progression using a pulsed arc
method. The arc should be directed into the joint at an angle slightly less than 90º. Start the arc,
and stop after a small shelf is established. Move the gun up approximately 3 mm, then start the arc
again and maintain the arc long enough to obtain penetration into the joint. Stop the arc and move up
another 3mm. Restart the arc again before the molten metal is completely cooled. Arc time should be
long enough to obtain penetration but stopped before the molten pool drops. The vertical joints can be
effectively welded in one pass regardless of the varying degree of joint gap.
FIGURE 32: ALIGNMENT
OF TAP CHANGER
See section B.3.A for dimensions of the
transformer tank opening required.
TANK
OPENING
FIT UP HOOKS
FIGURE 1
44
LEVEL UNDER
THIS SURFACE
SHIM ON EITHER HOOK TO LEVEL
BOTTOM PLATE OF SPRING DRIVE
FIGURE 33: WELD REQUIREMENT B U E I N S TA L L AT I O N
Attach the UZD® tank assembly to transformer per the procedure described above. The
BUE can be mounted directly under the UZD® Figure 34 or mounted lower than the
UZD® with the use of an off-set mount (longer drive shaft and drive shaft enclosure) per
Figure 35. These off-set shaft extensions are available in 60 mm, 500 mm, 1,000 mm
and 1,500 mm lengths. If it is desired to rotate the BUE 90º with respect to the UZD®, an
off-set shaft extension is required.
FIGURE 34: DIRECT MOUNT OF BUE
BELOW THE UZD®
45
FIGURE 35: OFFSET MOUNT OF BUE BELOW THE UZD®
OFFSET
1876
[73.9]
PLUS
OFFSET
1718
[ 67.6 ]
The UZD® and BUE are assembled at the factory so that both are
Should the locks be removed prior to assembly, there are six things
in the same tap position. It they get out of sync (on different tap
to check to verify that both UZD® and BUE are in the proper
positions) damage will occur at some point of operation. Before
position prior to attempted operation. First, in the BUE motor drive,
disassembly, shipping “locks” are installed. There is one lock on the
check that neutral position is indicated on the mechanical index
input shaft in the spring drive mechanism, see Figure 36, and one
position dial (position indicator). The black hand should be pointing
in the BUE where the hand crank is installed for manual operation,
straight up to position N. Second, verify that the red position
see Figure 37. It is critical that both devices be in the same position
indicator flag (located immediately above the mechanical position
when they are assembled on a transformer. Both the UZD and
indicator) is in the middle of the slot indicating BUE is on position.
the BUE are in the neutral position when the locks are applied. The
See Figure 37 to the right.
®
BUE can be assembled to the UZD and then the locks can be
®
removed. This will insure that neither device gets out of position
during assembly.
46
Third, the red line on the disc brake wheel should be in line with the
Fifth, in Figure 36 there is a split pin shown protruding through the
red line on the brake shoe. These lines are located in the upper left
lower left corner of the red shipping lock. This pin connects the
hand corner of the BUE directly in between and behind the springs
small level gear to the drive shaft from the BUE. The solid end of the
mounted on the disc brake as shown in Figure 38.
split pin should be towards you when facing the red shipping lock.
If the split end of this pin is facing out where the shipping lock was,
Looking down on the top of the BUE, Figure 39 below shows these
the spring drive mechanism is 180º out of position and damage will
lines before the BUE is assembled into it’s cabinet.
occur when UZD® is operated at the tap extremes. It is possible to
assemble these parts with the drive shaft 180° out of position so be
Forth, in the spring drive mechanism compartment, the large bevel
sure this is in the correct position.
gear driven by the small bevel gear in line with the drive shaft from
the BUE, should be aligned so that the bar molded into the back
of the large bevel gear is pointing to a hole drilled into the support
casting as shown in Figure 40.
FIGURE 36: BUE LOCKING DEVICE
FIGURE 38: DISC BRAKE WHEEL AND BRAKE SHOE ALIGNMENT
FIGURE 37: BUE LOCKING DEVICE
FIGURE 39: DISC BRAKE WHEEL AND BRAKE SHOE ALIGNMENT
47
Figure 41 shows the position of the drive arm connected to the
reversing switch Geneva wheel as it would appear if neutral is
FIGURE 40: SPRING DRIVE MECHANISM AND BUE
DRIVE SHAFT ALIGNMENT
approached from a Raise position. This position indicates that the
reversing switch in the oil compartment is on the back tap. The
reversing switch can be on either tap for assembly and adjusts itself
during operation.
In the oil compartment the reversing switch would be on the rear
contact. After assembly the reversing switch is normally left on the
front contact. It does not matter which stationary contact the reversing
switch is on for assembly. Figure 42 below shows the reversing switch
on the front contact.
Sixth, to verify neutral position in the oil compartment, the selector
(dial) switch should be pointing straight up in the 12:00 o’clock
position. See Figure 42.
FIGURE 41: DRIVE ARM POSITION IN NEUTRAL
Once it is known that all parts are in the proper position, attach
extension tube to the top of the BUE cabinet and install gasket. Install
the drive shaft through the extension tube and into the motor drive
coupling. Place gasket on top of extension.
Strap BUE to base on HY-BOY lift before
attempting to lift BUE into place.
Lift the BUE assembly (use Hy-Boy Lift) up to UZD® tank. Guide the
drive shaft through opening in the UZD® tank so it can be lined up and
inserted in the spring drive coupling.
Fasten extension tube to the UZD® tank. Secure the hardware with
Loctite 271 Threadlocker. Use one to two drops of Loctite to properly
secure hardware.
Use of neoprene, butyl or natural rubber gloves
is required to prevent skin contact with Loctite
271 Threadlocker.
48
FIGURE 42: SELECTOR SWITCH POSITION IN NEUTRAL
After installing the shaft, verify that the drive shaft has approximately 2–3 mm of end play and that the keys are positioned in
the slots as shown in Figure 43 below. If end play is greater than 2–3 mm AND/OR the keys are not properly positioned in the
slots, shim by placing up to four (4) cone washers on the bottom of the motor drive coupling and/or by placing up to two (2) cone
washers at the top of the motor drive coupling. Now the 2 shipping locks can be removed.
UP TO (2) CONE
WASHERS CAN BE
POSITIONED ABOVE
THE SHAFT TO HELP
POSITION THE KEYS
KEY
SPRING DRIVE
COUPLING
COUPLING KEY SLOT
BUE MOTOR
DRIVE COUPLING
UPPER KEY
SHOULD SIT
ABOVE THIS LINE
KEY
LOWER KEY
SHOULD SIT BELOW
THIS LINE
UP TO (4) CONE
WASHERS CAN BE
POSITIONED BELOW
THE SHAFT TO HELP
POSITION THE KEYS
FIGURE 43: BUE AND LTC COUPLING
49
L E A D C O N N E CT I O N S
Leads should be moved aside to accommodate connection of each
Tools
lead to the LTC. Loosening clamps/cables on top of the internal
1) 30 ft-lb Torque Wrench
assembly (top rack) may be necessary to reach these connections.
2) 3/8” Ratchet
3) 5/16” Allen Head Socket
FIGURE 44 - LTC LEADS BEFORE CONNECTIONS
4) Snips/Side Cutters
5) Drift
6) Adjustable Wrench
7) Hammer (Ground Straps)
8) Prick Punch (Ground Straps)
Materials
Loctite 27131 – Threadlocker
Procedures
1) Before lowering the core and coil assembly into the tank, crimp
the cable lugs onto the cables coming from the regulating
When making lead connections, begin with the bottom
winding. Crimps shall be made on either side of the terminal,
connections on A phase (left side) and work up. Next, secure the
not top or bottom, and consistently placed on the same side on a
leads to the LTC on C phase (right side), again working from bottom
given unit.
to top. Finally, complete the connections to B phase (center),
starting at the bottom and finishing at the top.
Each set of leads (19 leads for each phase) should be labeled
to match with the individual locations on the LTC. Verify that the
correct lead is connected to the correct location on the LTC. A
turns ratio test should be performed before the cover is secured
to the transformer.
FIGURE 45 - LTC LABELING
2) Do not taper the insulation at the end of the cable. After coil
dryout (vapor phase) the gap between the end of the cable lug
and the start of the insulation should not exceed 6 mm. Also the
end of the insulation on the cable should be secured so it does
not unravel.
3) Label each lead, indicating the position on the back of the phase
molding to which it should be attached see Figure 45. Retrieve
hardware for connecting leads qty 57 - M10 x 25 black oxide
SHCS bellville lock washers and bolts.
50
FIGURE 46: COPPER LEAD INSTALLATION
LTC TERMINAL
CABLE
6 MM
MINIMUM
When securing leads to the LTC,
no copper lead terminal can touch
another copper lead terminal. These
terminals must be installed parallel
to each other, with a minimum of 6
mm between terminals. See Figure
46 & 47.
TYP. LTC DECK
FIGURE 47 - COPPER LEAD TERMINALS TOO CLOSE OR TOUCHING
NOTE: On B phase, the LTC leads will cross
over one another – connections on the left side
of B phase will have the leads coming from the
right, and connections on the right side of B
phase will have the leads coming from the left.
NOTE: After securing the leads to the LTC
with a ratchet, two operators are required to
verify that each lead is properly torqued to 30
ft-lbs and in its correct location. One operator
performs the actual check of each lead in the
tank, calling out each lead as it is checked. The
second operator records appropriate data for
Quality Assurance documentation.
FIGURE 48 - LTC LEADS WITH CONNECTIONS COMPLETED
51
A S S E M B LY O F AC C E S S O R I E S
The packing list will detail any accessories removed for shipment. The openings on the UZD® for these devices have been fitted with
shipping covers. Remove the shipping covers, and check that the O-ring gaskets are securely pressed into the bottom of the flange
grooves. A light coating of white petroleum jelly will help prevent pinching of the gasket. Follow tightening torques per the Torque Values
shown in Table 4.
TABLE 4: TORQUE VALUES TABLE
B O LT S I Z E
GRADE 2
GRADE 5
GRADE 8
18-8 STAINLESS
BRASS
SILICON
BRONZE
2024-T2
ALUMINUM
1/4 - 20
66
96
144
75
62
69
46
1/4-28
76
120
168
94
77
87
57
5/16-18
132
204
300
132
107
123
80
5/16-24
144
228
300
142
116
131
86
3/8-16
240
360
540
236
192
219
143
3/8-24
276
420
600
259
212
240
157
7/16-14
360
600
840
376
317
349
228
7/16-20
420
660
960
400
327
371
242
1/2-13
600
900
1320
571
422
480
313
1/2-20
660
1080
1440
541
443
502
328
9/16-12
780
1320
150
682
558
632
413
9/16-18
900
1440
170
752
615
697
456
5/8-11
1080
150
220
1110
907
1030
715
5/8-18
1200
180
240
1244
1016
1154
798
3/4-10
160
260
380
1530
1249
1416
980
3/4-16
180
300
420
1490
1220
1382
958
7/8-9
140
400
600
194
159
178
1495
7/8-14
155
440
660
193
158
179
1490
1-8
220
580
900
287
235
265
184
1-14
240
640
1000
259
212
240
166
1-1/8-7
300
800
1280
413
337
383
265
1-1/8-12
340
880
1440
390
318
361
251
1-1/4-7
420
1120
1820
583
428
485
336
1-1/4-12
460
1240
2000
480
394
447
308
1-1/2-6
740
1940
3160
888
727
822
570
1-1/2-12
840
220
3560
703
575
651
450
B L U E VA L U E S A R E I N F O OT P O U N D S
W H I T E VA L U E S A R E I N I N C H P O U N D S
Conversion of Metric measures of torque:
Every effort has been made to present torque measurements in this instruction book in the English system.
Should you be confronted, for some reason, with a metric value the following conversion applies:
52
Nm times 8.85 = inch pounds Nm times 0.738 = foot pounds
kpm times 86.8 = inch pounds kpm times 7.23 = foot pounds
O I L P R E S E R VAT I O N – AU TO R E C H A R G I N G D E H Y D R AT I N G B R E AT H E R ( 2 N D G E N E R AT I O N )
The UZD® is designed to maintain a gas space above the oil to
The ARDB2 (or any silica gel breather) should be disconnected
allow for oil volume changes due to temperature. The UZD® tank
from the UZD® during oil draining or filling. Oil or oil vapor can coat
holds 100 gallons of oil for temperatures down to –25°C. For
the gel and prevent it from absorbing moisture. If the ARDB2 (or
temperatures between –25°C and –40°C, an offset in the float
other silica gel breather) is not disconnected during oil draining or
arm of the liquid level gauge is provided so the tank can hold 102
filling, the silica gel should be replaced. Be sure to reconnect the
gallons of oil.
ARDB2 after oil filling.
The standard liquid level gauge has one alarm contact to operate
For further information about the ARDB2 visit the
at low oil level but above critical oil level. An optional second alarm
Components/Transformer Health Products’ section of www.
contact can be provided to operate at the critical low oil level or
spxtransformersolutions.com or contact your SPX Waukesha
to indicate high oil level. Contacts at the critical low oil level are
Channel Partner.
typically used to trip the transformer off-line to prevent on arching
fault from occurring inside the LTC.
If the UZD® will be filled with natural ester fluid, SPX Waukesha
recommends that a Nitrogen Generator be used to bleed a small
Air above the oil must be vented to the atmosphere to allow arcing
amount of nitrogen across the gas space in the UZD® to, 1) sweep
gasses to escape. Air above the oil must also be dehydrated so
away arcing gasses generated, and 2) exclude oxygen and water
the oil stays dry. To accomplish this, SPX Waukesha recommends
vapor from entering the UZD® gas space. In this case, an ARDB or
that an Auto-Recharging Dehydrating Breather (ARDB2) be used
other silica gel breather is not required. Contact SPX Waukesha for
on the UZD®. The ARDB2 uses silica gel to remove moisture from
further information about this arrangement.
the air, features a built-in heater that turns on periodically to dry the
silica gel and is typically mounted at eye level for ease of inspection,
Figure 49 and 50. A 16.5 foot length of flexible tubing is provided
to connect the UZD® to the ARDB2. Clips should be provided on
the transformer by the OEM to restrain the tubing. There are studs
behind and to the top and bottom of the spring drive compartment
and behind and to the top of the BUE which can be used to secure
breather tubing.
53
FIGURE 49: BREATHER


This product is covered by one or more of the
following U.S. patents:
5,902,381
7,332,015
6,797,037
7,285,150
400 S. Prairie Ave
Waukesha, WI 53186 U.S.A. 800-835-2732


CLEAR NON-INDICATING SILICA GEL
2-5 mm diameter beads
SPX Components Part Number
1030-1797
1.00 kg
1-800-338-5526


400 S. Prairie Ave
Waukesha, WI 53186 U.S.A. 800-835-2732
CONFIDENTIAL AND PROPRIETARY
This document contains proprietary information of SPX Transformer Solutions, Inc. and may not be disclosed, copied, modified
or used without the written permission of SPX Transformer Solutions, Inc. If SPX Transformer Solutions, Inc. has authorized
your possession and/or use of this document, SPX Transformer Solutions, Inc. has granted you a limited, revocable license to use
this document and the information in it only for purposes specified by SPX Transformer Solutions, Inc. The document must be
promptly returned to SPX Transformer Solutions, Inc., after its use and/or upon demand by SPX Transformer Solutions, Inc.
Any possession, disclosure, copying, modification or use not authorized by SPX Transformer Solutions, Inc., can constitute a
violation of applicable law and be subject to severe penalties.
FIGURE 50: BREATHER INSTALLATION


400 S. Prairie Ave
Waukesha, WI 53186 U.S.A. 800-835-2732


400 S. Prairie Ave
Waukesha, WI 53186 U.S.A. 800-835-2732
CONFIDENTIAL AND PROPRIETARY
ARDB2-0000
54
This document contains proprietary information of SPX Transformer Solutions, Inc. and may not be disclosed, copied, modified
or used without the written permission of SPX Transformer Solutions, Inc. If SPX Transformer Solutions, Inc. has authorized
your possession and/or use of this document, SPX Transformer Solutions, Inc. has granted you a limited, revocable license to use
this document and the information in it only for purposes specified by SPX Transformer Solutions, Inc. The document must be
promptly returned to SPX Transformer Solutions, Inc., after its use and/or upon demand by SPX Transformer Solutions, Inc.
Any possession, disclosure, copying, modification or use not authorized by SPX Transformer Solutions, Inc., can constitute a
violation of applicable law and be subject to severe penalties.
O N - L I N E O I L F I LT R AT I O N U S I N G T H E O F 2
To keep the oil clean of arcing particles, SPX Waukesha recommends the use of the OF2 on-line Oil Filtration System, Figures 51A,
51B and 51C. Keeping the oil clean and dry will extend contact life and can extend the time between internal inspections. For further
information, visit the Components/Transformer Health Products’ section of www.spxtransformersolutions.com or contact your
SPX Waukesha Channel Partner.
FIGURE 51A: OIL FILTRATION SYSTEM (2ND GENERATION) – OF2
55
FIGURE 51B: OIL FILTRATION SYSTEM (2ND GENERATION) – OF2
ENCLOSED OIL FILTRATION SYSTEM SPECIFICATIONS
GENERAL:
Ambient Temperature Range: from -40°C to 50°C*
Fluid Operation Temperature: > -10°C to 150°C
Dimensions: 33.5"W x 13.7D x 34.5"H
Color: ANSI 61 Standard, Others Available
Spill Containment: Built-in 5-gallon Catch Sump to Capture Leaks. Optional Sump Alarm Available.
Oil Inlet: Convenient Input 3-way Valve for Addition of Oil Make-Up and Sample Collections
With Inlet Y-Strainer to Protect Pump From Large Debris.
Oil Outlet: Window Visible Flow Indicator (Paddle Wheel)
Mounting: Pad or Wall Mount
ENCLOSURE:
Type: Standard With Custom NEMA 3R; Stainless Steel Optional
Latch: 3 Way Latching System per UL Requirements
Enclosure Anti-Condensation: Efficient 120 VAC Thermostat-Free, High Recovery PTC2 heater (200/400 watts)
Fluid Heater (optional): Optional Proprietary Designed PTC Canister Heaters - Cannot Overheat Fluids
Venting: Duct Filters Both Sides of Cabinet
Documentation: Pocket for Operation Instructions Provided Inside of the Cabinet Door
PUMP/MOTOR:
Canister : 7x18 Compliant With Most Major Replacement Depth Filters
: Unique Tilt-Out Canister Design to Allow for Tool-Less Filter Maintenance
: Air Vent Valve and Flexible Drain Tube Allow Spill-Free Filter Changes
Filter: Depth Filter Water and Particulate Standard. Others Available
: Axial Flow Maintains Fluids at 12/10 ISO or NAS 4, ß5=500, ß3=150
: 3 Micron Absolute, Less Than 1 Micro Particle Removal, 0.5 Micron When Loaded
: Reduces Water to Less Than 15 ppm
CONTROLS:
Standard Controls: 1-160 psi Oil Filled Gauge and Visible Flow Indicator
: High Pressure Output Alarm Wired to Alarm Contact and Latching Relay
: System Designed For Continuous Operation, Timer Option is also Included
Electrical: 120 VAC Single Phase. Transformer for 230 VAC Operation Available
: Automatic System Restart After Power Interruption
: Relay Provided for Remote Shutdown
: Optional Run Cold Circuit Available, Runs System Continuously Below 20°F
C 2009 SPX Transformer Solutions, Inc. All rights reserved.
WAUKESHA OIL
FILTRATION SYSTEM
DRAWN
OIL FILTRATION
CONFIGURATOR
NEXT ASSY
CHECKED
MATERIAL
A. MARTIN
SCALE
NTS
DATE
6/10/2009
SHEET
2
OF
D
56
MATERIAL ANALYSIS NUMBER
TITLE
EQUIPMENT TYPE / NO.
2
CHECKLIST/ECR NUMBER
-
-
TOL. TO BE AS SHOWN UNLESS OTHERWISE NOTED
.XX ± .O1 .XXX ±.005 X°±1°
9011 GOVERNORS ROW
DALLAS, TEXAS 75247
DATE PERFORMED
DRAWING NUMBER
OF2-CONFIG
REV.
A
VERIFIED
TO OEM
CONFIDENTIAL AND PROPRIETARY
This Drawing contains proprietary information of SPX Transformer Solutions, Inc. and may not be disclosed, copied, modified or used
without the written permission of SPX Transformer Solutions, Inc. If SPX Transformer Solutions, Inc. has authorized your possession and/or
use of this Drawing, SPX Transformer Solutions, Inc. has granted you a limited, revocable license to use this Drawing and the information in
it only for purposes specified by SPX Transformer Solutions, Inc. The Drawing must be promptly returned to SPX Transformer Solutions, Inc.
or destroyed after its use and/or upon demand by SPX Transformer Solutions, Inc. Any possession, disclosure, copying, modification
or use not authorized by SPX Transformer Solutions, Inc. can constitute a violation of applicable law and be subject to severe penalties.
FIGURE 51C: OIL FILTRATION SYSTEM (2ND GENERATION) – OF2
Oil Filtration Systems
OF 2- XXXXXXX
SYSTEM TYPE
STANDARD SYSTEM (120VAC)
STEEL NEMA 3R CAB
1/2 HP MOTOR
5 GAL LEAK SUMP
OIL LEAK DETECTION
TILT OUT FILTER CANISTER
VISUAL FLOW INDICATOR
0-100 PSI, OIL FILLED, GAGE
RUN INTERVAL TIMER
RUN TIMER BYPASS SWITCH
RUN-TIME METER
REMOTE SHUTDOWN
AUTO RESTART WITH POWER
FAILURE (1030-1393 CAB.)
SAME AS OPTION "A"
EXCEPT WITH
STAINLESS STEEL CAB
(1030-1656 CAB.)
SAME AS OPTION "A"
EXCEPT FOR 240VAC
OPERATION
240VAC - 120VAC
TRANSFORMER
CONVERSION WIRING
SAME AS OPTION "A"
EXCEPT WITH
STAINLESS STEEL CAB &
240VAC OPERATION
240VAC - 120VAC
TRANSFORMER
CONVERSION WIRING
PIPING
PUMP CAPACITY
A
AMBIENT TEMPERATURE RANGE
1 GAL PER MIN.
MECH. SEALS
INTEGRAL BYPASS
0
0
B
PIPING
LOW FLOW / LEAK ALARMS
FILTER PACKAGE
WAUKESHA STAN.
7 X 18 DEPTH
COMO ELEMENT
1030-1508
7 X 18 DEPTH
COMO ELEMENT -D
1030-1542
1
7 X 18 DEPTH
FILMAX ELEMENT
1030-1385
2
C
D
STANDARD
LOW FLOW & LEAK
DETECTION WITH
LOCAL LED
INDICATOR AND
ALARM CONTACTS
0
SAME AS OPTION "0"
EXCEPT WITH
FLOW TRANSMITTER
(4-20 ma) 1030-1530
1
-50° C TO 50° C
AMBIENT
HI-RECOVERY 200/400W
ANTI-CONDENSATION
HEATING
NONE
0
0
ENTRANCE TUBE
ONLY
1030-014K
1
ENTRANCE TUBE
AND HOSE
1030-048K
2
HIGH PRESSURE ALARMS
STANDARD
HIGH PRESSURE
DETECTION WITH
LOCAL, WINDOW
VISIBLE, LED INDICATOR
SYSTEM SHUTDOWN,
AND ALARM CONTACT
0
SAME AS OPTION "0"
EXCEPT WITH
PRESSURE TRANSMITTER
(4-20 ma)
1
15.60
34.98
38.57
33.37
13.79
WITH DOOR
INSTALLED
57
P R E S S U R E S W I TC H
General
The pressure switch is designed to indicate excessive pressure in
Under normal operating conditions the switch will operate in
the tap changer switching compartment if a fault should occur. It is
less than 5ms.
the function of the pressure switch to send a signal to transformer
protective equipment to remove the transformer from the system in
When the oil pressure on the area of the piston exceeds the
the event of a fault in the tap changer.
spring load on the piston, the piston will move toward the switching
element, thus actuating it. For electrical connection a terminal block
Design and Operation
is provided on the switching element.
As shown in Figure 52, the pressure switch assembly consists of a
ball valve 1, street tee 2, relay housing 3 and pipe plug 4.
We recommend this be connected to trip the main circuit breaker.
The transformer should be taken out of service and the tap changer
The relay housing, as shown in Figure 53, contains the
pressure sensor with diaphragm, piston, spring, adjusting nut
and switching element .
LEG E N D – FOR FIG U R E 52
1 ) BA L L VA LV E
2) STR E ET T
3 ) R E L AY H O U S I N G
4) PI PE PLUG
FIGURE 52: PRESSURE SWITCH
58
inspected in the event of operation of the pressure switch.
Mounting and Connection
The pressure switch is mounted to a flange on the tap changer
out with a pressure gauge in combination with an air pump
switching compartment. Electric connection should be made
connected to the test tap. The pressure setting is adjusted by
to an intermediate lockout relay with a main breaker. Electrical
variation of the spring load on the piston through the adjusting nut.
rating of the switch is 125/250/480 VAC, 15 A and 24-30 VDC,
2 A resistive and 1 A inductive. At 125 VDC, 0.5 A resistive
To adjust the pressure set point remove cover. Loosen Phillips
and 0.03 A inductive
screw adjustment lock. Adjust set point by turning 5/8” hex
adjustment screw clockwise (left) to raise set point, or counter
clockwise (right) to lower set point. Retighten adjustment lock.
Adjusting and Testing
The switch has a setting range from 1 psi to 20 psi. All pressure
relays are preset at the factory to close at 4.3 psi ±5%. When
See Pressure Switch section under Annual Inspections in the
the tap changer Major Inspection is carried out or during regular
UZD® Field Maintenance manual for further instructions.
routine inspections a test of the operating pressure should be
made. For this purpose a ball valve is provided. The test is carried
KNOCK
OUT
COM.
N.O.
N.C.
ADJUSTMENT:
TURN IN TO
RAISE SET
POINT
ADJUSTMENT
LOCK
TOP OF HEX
LOW
MID
HIGH
CLEARANCE FOR
1/4" [6.35] SCREW
2 MT'G. HOLES
FIGURE 53: RELAY HOUSING
59
LTC O I L
New mineral oil should be used to fill the UZD® and meet the specified values detailed below:
TABLE 5: RECOMMENDED MINERAL OIL SPECIFICATIONS
ASTM TEST METHOD
ANSI /ASTM D-3487 LIMITS
P H YS I CA L P R O P E R T I E S
Aniline point, ºC
D611
63-84
Color
D1500
0.5 max
Flash point, ºC
D92
145 min
Interfacial tension @ 25ºC (dynes/centimeter)
D971
40 min
Pour point, ºC
D97
-40 max
Specific gravity @ 15ºC/15ºC
D1298
0.91 max
Viscosity, SSU/cSt @
D88/D445
100ºC
36/3.0 max
40ºC
66/12.0 max
0ºC
350/76.0 max
Polychlorinated Biphenyls (PCBs) ppm
D-4059
Not Detectable
Visual appearance
D1524
Clear and Bright
Approved antioxidant content, wt %
D2668, D1473
0.30 max
Corrosive sulfur
D1275 Modified 1
Noncorrosive
Moisture, ppm
D1315, D1533
35 max
Neutralization number, mg KOH/g of oil
D974
0.03 max
Oxidation stability Method A (acid/sludge test)
D2440
C H E M I CA L P R O P E R T I E S
1
Test to be run for 48 hours @ 150ºC
72 hours
sludge, wt %
0.10 max
Neutralization value, mg KOH/g
0.30 max
164 hours
sludge, wt %
0.20 max
Neutralization value, mg KOH/g
0.40 max
Method B (rotary bomb oxidation test)
D2112
195 min.
D877
30 min
E L E CT R I CA L P R O P E R T I E S
Dielectric breakdown voltage at 60 hertz
Disc electrodes, kV
VDE electrodes, kV
@ 0.040-in. gap or
D1816*
28 min
@ 0.080-in. gap
D1816*
56 min
Dielectric breakdown voltage 25ºC
impulse conditions, kV
Needle (negative)-to-sphere (grounded)
@ 1-in gap
D3300
145 min
Power factor at 60 hertz, % at:
25ºC
D924
0.05 max
100ºC
D924
0.30 max
Gassing Tendency @ 80 ºC (µL/min)
D-2300 B
+ 30 max
*D1816 only applies to new oil that has been filtered, dehydrated and degassed.
60
Oil shall be PCB-free according to existing current law. Properties
Taking regular oil samples from LTCs for use in Dissolved Gas
as listed are only attainable on new oil as received from the refinery.
Analysis and Oil Quality tests is becoming commonplace. As such,
Oil contained in equipment as received from the manufacturer,
you may want to add some additional oil to the UZD® to allow for
when properly sampled from such equipment, typically exhibits
some additional samples to be removed before make up oil has to
characteristics slightly different from those obtained from new
be added. It is permissible to fill the UZD® tank with 102 gallons
oil that has not been in contact with apparatus/constructional
of oil. The liquid level gauge will read above the 25°C mark when
materials. In such cases, the oil should be evaluated per IEEE
this extra oil is added. The information provided below shows the oil
C57.106 (most recent release) for acceptance and maintenance of
level, oil level float arm angle and oil level for both 3.5 and 6 inch
insulating oil in equipment.
diameter liquid level gauges and for both 100 and 102 gallons of
fluid at various temperatures.
Acceptance Test
Samples for testing are to be obtained and tested in accordance
TABLE 6: 3.5 INCH DIAMETER LIQUID LEVEL GAUGE SETTINGS & VOLUMES
with the latest issue of ASTM test methods (currently ASTM Test
3.5 INCH DIAMETER LIQUID LEVEL GAUGE
Method D923).
UZD® TANK OIL VOLUMES
Oil Temperature
Gals.
Determination of Quantity
90
107
10
101
The usual temperature for measurement of oil delivered under this
25
102
6
54
specification is established at a 15.5ºC basis in accordance with
-50
96
the standard abridged volume or correction table for petroleum oil,
TRIP
ASTM D1250.
UZD® LIQUID LEVEL GAGE SETTINGS
Oil Filling Procedure
Never fill UZD® tap changers while transformer is in its vacuum
cycle!
Gals.
mm
-5
Float Length =
45
Float Arm Length =
88
90
Float Angle =
45
-50
Float Angle =
-55
Float Angle =
-64
TRIP
UZD TANK OIL VOLUMES
®
UZD® tap changers must be vented during oil filling. To vent,
either remove hose to breather or remove Rapid Pressure Rise
relay(RPR)/cover plate. In either case, make sure the breather is
Oil Temperature
Gals.
90
105
8
79
3
32
25
100
disconnected so that any oil vapor does not contact the silica gel as
-20
96
oil coating on the gel prevents it from absorbing moisture.
TRIP
Gals.
mm
-5
UZD LIQUID LEVEL GAGE SETTINGS
®
The UZD® holds 100 US gallons of oil. The cold temperature option
Float Length =
45
for the UZD® holds 102 US gallons.
Float Arm Length =
88
90
Float Angle =
45
Zero out oil counter. Fill LTC with oil through the oil drain valve at
-20
Float Angle =
-29
bottom left side of UZD® tank. Fill to the 25°C mark on the liquid
TRIP
Float Angle =
-35
level gauge, also indicated below. This assumes 25°C. If oil is other
than 25°C adjust for temperature. Close valve when level has been
reached. Shut off oil at pumping station.
61
TABLE 7: 6.0 INCH DIAMETER LIQUID LEVEL GAUGE SETTINGS & VOLUMES
6.0 INCH DIAMETER LIQUID LEVEL GAUGE
10ºC ×0.000774/ºC×102 gallons ×231in3 ×1/630in2 = 0.289in
UZD® TANK OIL VOLUMES
(see Figure 54 for measuring points, oil levels and oil level float arm travel)
Oil Temperature
Gals.
90
107
10
101
25
102
6
54
-50
96
Gals.
mm
FIGURE 54: OIL LEVEL GAUGE
25 C OIL LEVEL
PRESSURE RELIEF DEVICE FLANGE
TRIP
-5
MIN OIL LEVEL
UZD® LIQUID LEVEL GAGE SETTINGS
Length To Center Of Float =
77
Float Arm Length =
99
8.50
[215.9]
90
Float Angle =
48
-50
Float Angle =
-41
Float Angle =
-45
TRIP
HI
35 MM
35 MM
LO
UZD TANK OIL VOLUMES
®
Oil Temperature
Gals.
90
105
8
79
25
100
3
32
-20
96
Gals.
TRIP
6.61
[168.0]
10.0
[254.0]
ANTI-SYPHON
HOLE 6MM ABOVE
MINIMUM OIL LEVEL
mm
-5
UZD LIQUID LEVEL GAGE SETTINGS
®
Float Length =
51
Float Arm Length =
88
90
Float Angle =
48
-20
Float Angle =
-31
TRIP
Float Angle =
-37
S H I PPI NG
The “cold” tank is good to -50ºC. Oil volume of “Cold” temp tank
The motor drive mechanism must be protected against
is 102 gallons, this requires on offset in the float arm to add the
condensation. Whenever control power is available, the heater
additional 2 gallons of oil at 25ºC. Oil changes in volume 0.000774
should be energized. When power is not available, use of a drying
cubic inches per ºC (approximate value at the normal temperature
agent in the motor drive compartment will suffice as long as the
range of the LTC). Tank dimensions at the top is 36” X 17.5” = 630
vents are sealed.
square inches. One gallon of liquid is 231 cubic inches. For a 10º
increase (10 X 0.000774 X 102 gal) = 0.78948 increase. Volume
The UZD® can be shipped with oil in the oil-filled compartment,
change then is (.789 X 231) = 182.37 cubic inch increase.
independent of whether or not oil is located in the main transformer
Every one-inch of oil in this part of the tank is 630 cubic inches.
tank. Shipping the load tap changer oil-filled simplifies the field
Therefore (182.37 cu/in / 630 sq./in) = 0.289 inch change in
assembly process, unless an internal LTC field inspection will be
oil level per 10 ºC.
completed upon receipt.
Do not energize the transformer until both
the transformer and UZD® have been properly
filled with oil.
62
E L E CT R I CA L C O N N E CT I O N A N D T E S T I N G
FI E LD COM M I SS ION I NG
General
Reassemble any accessories that have been removed for shipment.
Before the transformer is energized, testing should be performed to
If the load tap changer was shipped without oil, fill with oil as
verify that all mechanical and electrical connections are correct and
described in the Oil Filling procedure in the Major Inspection section
the load tap changer motor and drive mechanism are functioning
of the Field Maintenance Manual.
properly. When testing the transformer, the load tap changer can be
operated either electrically or manually by use of the hand crank.
Ensure the Auto-Recharging Dehydrating Breather (ARDB2) is
connected to the oil-filled compartment and electrically wired to
Shipping
receive control power. Turn control power to the ARDB2 off and
The light bulb and its enclosure in the BUE motor drive mechanism
then on again to start a regeneration cycle. Verify warm up of
should be removed from its socket and wrapped in bubble wrap or
the ARDB2.
sheet foam then secured in the BUE compartment for shipment of
the transformer. Failure to do this may result in damage.
Confirm the OF2 oil filtration system is connected to the oil-filled
compartment and electrically wired to receive control power. Turn
Connecting and Testing
the filter on and verify flow and proper operating pressure.
Connect the power supply for the motor, controls and auxiliary
devices as shown on the schematic provided with the load tap
All inspections as described in the ANNUAL INSPECTION section
changer. Connect to all alarm contacts per this same schematic.
of the UZD® Maintenance Manual should be performed prior to the
transformer being energized on site.
Operate the motor drive mechanism by means of the hand crank
to one of the tap positions in the middle of the range but not a
Verify that the LOCAL/REMOTE switch is in the desired setting.
through-position (a through-position typically includes a letter, such
as RN). Turn the control selector switch to the LOCAL position and
give an impulse for a RAISE operation. Verify the tap changer moves
in the raise direction. Continue to the 15R position. Use the hand
crank to move the tap changer to position 16R and verify that the
normally-closed contact on limit switch LS-1 opens to block current
to the drive motor. This can be done on the terminals of LS-1 (see
schematic Figure 21, page 34 for terminal identification). Continue
to operate the tap changer manually for another turn or two and
verify that the mechanical end stop operates (preventing further
movement).
Operate manually back to 16R. An in-service position is attained
when the flag indicator in the motor drive mechanism is in the
center of travel below the word POSITION. Then operate manually
or electrically to 15L and repeat the above procedure.
Electrical Tests on Transformer
Factory testing on the transformer can now be performed.
63
Glossary
Arcing switch: A switching device used in conjunction with a
Main contacts: For resistance-type LTCs, a set of through
tap selector to carry, make and break current in circuits that have
current-carrying contacts that has no transition impedance between
already been selected.
the transformer winding and the contacts and commutates the
current to the main switching contacts without any arc.
ARDB: Waukesha brand name for Auto-Recharging Dehydrating
Breather, a self recharging silica gel breather that dehydrates air
Main switching contacts: For resistance-type LTCs, a set of
going into a compartment.
contacts that has no transition impedance between the transformer
winding and the contacts and makes and breaks current.
Arcing tap switch: A switching device capable of carrying
current and also breaking and making current while selecting a tap
Maximum rated step voltage: Highest value of rated step
position, thereby combining the duties of an arcing switch and a tap
voltage for which the LTC is designed.
selector. Also used interchangeably in this manual as a Selector
Switch.
Maximum rated through current: The rated through current
for which both the temperature rise of the contacts and the service
Circulating current: Current that flows through the transition
duty test apply.
impedance or reactor as a result of two taps being bridged during a
tap change operation.
Number of inherent tap positions: The highest number of tap
positions for half a cycle of operation for which an LTC is designed.
Cycle of operation: Movement of the LTC from one end of its
range to the other and back to its original position.
Number of service tap positions: Number of tap positions for
half a cycle of operation for which an LTC is used in a transformer.
Design test: Test performed on an LTC or the components of an
NOTE: The above two terms are generally given as the ± values
LTC to prove compliance with standards.
of the relevant numbers, e.g. ± 16 positions. They are, in principle,
valid also for the motor-drive mechanism. When the term number
Drive mechanism: Means by which the LTC is actuated.
of tap positions is used in connection with a transformer, it always
refers to the number of service tap positions of the LTC.
Insulation level: Withstand values of the impulse and power
frequency test voltages to ground and, where appropriate, between
OF2: Waukesha brand name for it’s oil filtration system
the phases and between those parts where insulation is required.
Plus/minus operation: A winding arrangement in which one
Load tap changer (LTC): A selector switch device, which may
or the other end of the tap winding is connected by a reversing
include current interrupting contactors, used to change transformer
change-over selector to the main winding and allows use of the
taps with the transformer energized and carrying full load.
taps in a buck or boost mode when travelling through the tapping
range.
64
Rated frequency: Frequency of the alternating current for which
Routine test: A test made on each completed LTC to establish
the LTC is designed.
that the LTC is without manufacturing defects, with the design
having been verified by a design test.
Rated step voltage: For each value of rated through current, the
highest permissible voltage between successive tap positions.
Switched current: Prospective current to be broken during a
NOTE: Step voltage of resistance-type LTCs means tap-to-tap
switching operation by each set of main switching or transition
voltage (no bridging position).
contacts or vacuum interrupters (resistance-type LTC) incorporated
in the arcing switch or arcing tap switch.
Rated through current: The current flowing through the LTC
toward the external circuit, which the apparatus is capable of
Tap change operation: Complete sequence of events from the
transferring from one tap to another at the relevant rated step
initiation to the completion of the transition of the through current
voltage and which can be carried continuously while meeting the
from one tap position to an adjacent one.
requirements of stated standards.
NOTE: Within the maximum rated through current of the LTC, there
may be different assigned combinations of values of rated through
Tap selector: Device designed to carry, but not to make or break,
current and corresponding rated step voltage. When a value of rated
current, used in conjunction with an arcing switch to select tap
step voltage is referred to as a specific value of rated through current,
connections.
it is called the relevant rated step voltage.
Transition contacts: For resistance-type LTCs, a set of contacts
Recovery voltage: Voltage that appears across each set of main
that is connected in series with a transition impedance and makes
switching, or transition, contacts of the arcing switch or arcing tap
and breaks current.
switch after these contacts have broken the switched current.
Transition impedance: A resistor or reactor consisting of one or
Relevant rated step voltage: The value of rated step voltage
more units that bridge adjacent taps for the purpose of transferring
that corresponds to a specific value of rated through current.
load from one tap to the other without interruption or appreciable
change in the load current, at the same time limiting the circulating
Reversing change-over selector: A change-over selector
current for the period that both taps are used. Normally, reactance-
that connects one or the other end of the tap winding to the main
type LTCs use the bridging position as a service position, and,
winding.
therefore, the reactor is designed for continuous loading.
Reversing switch: Another commonly used name for reversing
change-over selector.
65
Appendix
Acceptance Test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Adjusting and Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
Arcing Tap Switch (Tap Selector Switch). . . . . . . . . . . . . . . . . . . . . . 8, 28
Assembly of Accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Assembly to Transformer & Commissioning . . . . . . . . . . . . . . . . . 43-63
Automatic Operation Local Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Auxiliary Contact. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Brake. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
BUE Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45-49
BUE Motor Drive Mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-27
Cabinet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Cable Lugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Conductors from Windings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Connecting and Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Construction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-27
Contact Device. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Contact Life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Contact Timing Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Continuation Contact (84C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Conversions of Metric Measures Torque. . . . . . . . . . . . . . . . . . . . . . . . 52
Damage Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Design and Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Determination of Quantity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Electrical and Mechanical End Stops. . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Electrical Connection and Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Electrical Test on Transformer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Epoxy Phase Moldings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7
Field Commissioning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Flywheel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Gearing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58, 63
General Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
Geneva Gear. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64-65
Grounding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Hand Crank. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Heater. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Indication. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Indicator Flag. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Interlocking Contact. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Lead Connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50-51
Loading Beyond Nameplate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Load Tap Changer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28-33
Local Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
LTC Oil. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60-62
LTC Tank Air-Filled Compartment–Spring Drive Mechanism. . 12-15
LTC Tank Oil-Filled Compartment–Tap Changer Live Parts. . . . 6-11
Maintaining Contact. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Maintaining Contact Brake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Mechanical Life. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
66
Mineral Oil/FR3 Fluid Operating Temperatures. . . . . . . . . . . . . . . . . 41
Moisture Evaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Mounting and Connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Motor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Motor Drive Mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33-37
Oil Filling Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61-62
Oil Preservation – ARDB2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53-54
One-turn Shaft. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
On-Line Oil Filtration – OF2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55-57
Operation at Lower and Higher Ambient Temperatures . . . . . . . . . 42
Operation Counter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Operational Description – Schematic. . . . . . . . . . . . . . . . . . . . . . . . 33-35
Operating Principles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28-37
Optional Accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Over-current Blocking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Over-current Relay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Position Indicator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Preparation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Pressure Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58-59
Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50-51
Product Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Rating Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Ratings - Insulation Level. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Receiving Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Remote Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Reverse Power Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Reversing Change-Over Selector Geneva Gear. . . . . . . . . . . . . . . . . 14
Reversing Change-Over Selector (Reversing Switch). . . . . . . . . . . . . 8
Reversing Change-Over Selector for Plus/Minus Switching. . . . . 31
Schematic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Shipping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Short Circuit Strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Sound Level. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Standards and Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Start Contact. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Step-by-Step Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Step Voltage and Through Current. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Switching Sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Tank and Accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-19
Technical Data & Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . 38-42
Temporary Storage Before Assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Through-positions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31, 37
Tie-in Resistors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
Transition Resistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Transition Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Unpacking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
UZD® Tank - External . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-19
Weight and Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-17
Welding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Wiring and Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Figure & Table Numbers
FIGURE NUMBERS
Figure 1: UZD® with BUE Unit Attached . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 28: Predicted Contact Life with Breaking Currents . . . . . . 40
Figure 2: Cast Epoxy Phase Molding with Contacts Assembled. . . 7
Figure 29: Small Cable Lug, 1 AWG . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Figure 3: Stationary Contact. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 30: Medium Cable Lug, 4/0 AWG . . . . . . . . . . . . . . . . . . . . . . 42
Figure 4: Main Moving Contact Assembly
with Transition Resistor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 31: Large Cable Lug, 300 MCM. . . . . . . . . . . . . . . . . . . . . . . . 42
Figure 5: Reversing Change-Over Selector (Reversing Switch). . 10
Figure 33: Weld Requirement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Figure 6: Main Switch and Spring Drive Compartment. . . . . . . . . . 11
Figure 34: Direct Mount of BUE Below the UZD®. . . . . . . . . . . . . . 45
Figure 7A: Spring Drive Mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 35: Offset Mount of BUE Below the UZD®. . . . . . . . . . . . . . 46
Figure 7B: Exploded Spring Drive Mechanism. . . . . . . . . . . . . . . . . . 15
Figure 36-37: BUE Locking Device. . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Figure 32: Alignment of Tap Changer. . . . . . . . . . . . . . . . . . . . . . . . . . 44
Figure 8A: Dimensions for External UZD® Tank . . . . . . . . . . . . . . . . 16
Figure 38-39: Disc Brake Wheel and Brake Shoe Alignment . . . 47
Figure 8B: Dimensions for Mounting Bracket on Bottom of BUE
to Transformer Tank Wall Used with Offset Shaft Extension. . . . . 17
Figure 40: Spring Drive Mechanism and
BUE Drive Shaft Alignment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Figure 8C: Dimensions for Conduit Entrance in Back of BUE. . . 17
Figure 41: Drive Arm Position in Neutral. . . . . . . . . . . . . . . . . . . . . . . 48
Figure 8D: Typical Location of UZD on Transformer . . . . . . . . . . . 17
Figure 42: Selector Switch Position in Neutral. . . . . . . . . . . . . . . . . . 48
Figure 8E: Detail of Tank Opening. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 43: BUE and LTC Coupling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Figure 8F: Detail of Phase Molding Extension
Into Transformer Tank. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 44: LTC Leads Before Connections. . . . . . . . . . . . . . . . . . . . . 50
Figure 8G: Detail of UZD® Mounting Flange. . . . . . . . . . . . . . . . . . . 18
Figure 46 - 47: Copper Lead Installation. . . . . . . . . . . . . . . . . . . . . . . 51
Figure 9: BUE Cabinet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 48: LTC Leads with Connections Completed . . . . . . . . . . . . 51
Figure 10A: Motor Drive Mechanism - Exploded View. . . . . . . . . . .22
Figure 49-50: Breather and Breather Installation Kit Drawing. . . 54
®
Figure 45: LTC Labeling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Figure 10B: Motor Drive Mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 51A-C: Oil Filtration System - OF2 Kit Drawing. . . . . . 55-57
Figure 10C: Motor Drive Mechanism - Exploded View. . . . . . . . . . 25
Figure 52: Pressure Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Figure 11-18: Stationary Contact Positions . . . . . . . . . . . . . . . . . 28-30
Figure 53: Relay Housing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Figures 19A-C: Reversing Change-Over Selector for
Plus/Minus Switching. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 54: Oil Level Gauge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Figure 20A: LTC and Transformer Winding Connections
with Series Transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
TABLE NUMBERS
Table 1: Electrical Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Figure 20B: LTC and Transformer Winding Connections
without Series Transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Table 2: Estimated Contact Life. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Figure 20C: LTC and Transformer Winding Connections
with Auto Connected Series Transformer . . . . . . . . . . . . . . . . . . . . . . 33
Table 4: Torque Values Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Figure 20D: Connection Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 21: Control Schematic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 22: Control Schematic - Device Legends. . . . . . . . . . . . . . . . 35
Figure 23: Contact Timing Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Table 3: Available Cable Lug Sizes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Table 5: Recommended Mineral Oil Specifications. . . . . . . . . . . . . . 60
Table 6: 3.5 Inch Diameter Liquid Level Gauge
Settings & Volumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Table 7: 6.0 Inch Diameter Liquid Level Gauge
Settings & Volumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Figure 25: UZD® LTC Name Plate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Figure 26: Motor Drive Name Plate. . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Figure 27: Step Voltage vs. Rated Through-Current. . . . . . . . . . . . . 40
67
Technical Manual
Load Tap Changer
Type “UZDRT”
w w w. s p x t r a n s f o r m e r s o l u t i o n s . c o m
United States locations
WAU K E S H A H E A D Q UA R T E R S
GOLD S BORO PLANT
COM PON E NTS
S E RVICE
400 South Prairie Avenue
2701 US HWY 117 South
9011 Governors Row
Emergency Service Available
Waukesha, WI 53186
Goldsboro, NC 27530
Dallas, TX 75247
24/7/365: 888 365 24x7
800 835 2732
800 758 4384
800 338 5526
800 758 4384
SPX Transformer Solutions, Inc. (formerly Waukesha Electric Systems, Inc.) is one of the largest U.S. manufacturers of power transformers and a valued supplier of complete
transformer service solutions, reverse-engineered components and replacement parts as well as a variety of substation-applicable training classes for all skill levels.
Manufacturing locations include our headquarters in Waukesha, Wisconsin as well as satellite sites in Goldsboro, North Carolina and Dallas, Texas.
WAU K E S H A ® T RAN S F OR M E R S
Our modern transformer manufacturing operations in Waukesha, Wisconsin and Goldsboro, North Carolina have amassed over 80 years of combined experience producing
high quality power transformers that meet stringent customer demands. Utilizing sophisticated computer-controlled equipment and test systems, SPX Waukesha also maintains
one of the shortest production cycles in the industry, which allows the team to respond quickly to customer delivery and installation requirements.
WAU K E S H A ® S E RV I CE
Waukesha® Service can provide complete transformer service solutions for almost any manufacturer’s units including installation, maintenance, relocation, testing and
technical assessments; oil processing, dryouts and retrofills; corrective and preventative maintenance; load tap changer field retrofits and repairs. Along with a vast number of
skilled personnel located strategically across the country, we manage one of the largest fleets of specialized transformer service equipment in the United States. This allows us
flexibility, optimized installation hours and costs while helping us provide efficient, safe and high quality service to our customers.
WAU K E S H A ® CO M P ON E NTS A N D TR A I N I N G
Waukesha® Components operates a manufacturing, testing and training facility in Dallas, Texas as a leading supplier of parts for most major current and obsolete load tap
changer (LTC) and oil circuit breaker brands as well as being the original manufacturer of a line of Transformer Health Products®. Additionally, we offer a variety of LTC
services, including maintenance training, failure analysis reporting and complete overhauls at this location while also continuing to build our reputation as an industry leader in
reverse-engineering and design enhancement.
S PX CO R P O RATI O N
SPX Transformer Solutions, Inc. is part of SPX Corporation (NYSE: SPW). SPX is a global, Fortune 500 company providing products and services for multiple industries,
including power and energy, food and beverage, oil and gas and industrial infrastructure. Based in Charlotte, North Carolina, SPX operates in more than 35 countries with over
15,000 employees. To learn more, visit www.SPX.com.
© 2015 SPX Transformer Solutions, Inc.
UZD-1211 (Rev 5/15)