Voltage Regulating Apparatus
Spring-Drive and Direct-Drive Tap Changer Switches in VR-32
Operating, Maintenance, Troubleshooting and Parts
Replacement Instructions
Cooper Power Systems
Quality from
Cooper Industries
Service Information
S225-10-2
Figure 1A.
928D spring-drive tap changer.
Figure 3A.
770B direct-drive tap changer.
Figure 2A.
170C spring-drive tap changer.
Figure 4A.
660C direct-drive tap changer.
CONTENTS
Instructions ......................................
General .............................................
Motor ...............................................
Holding switch .................................
Contacts ..........................................
Reversing switch .............................
Maintenance ....................................
Spring-drive tap changers ..............
Drive mechanism .............................
Operational sequence .....................
Service and troubleshooting ............
Contact inspection .........................
Tap changer inspection ..................
Troubleshooting .............................
Replacement of tap changer parts .
Contact replacement .....................
Main movables ............................
Main stationaries .........................
Reversing switch .........................
Motor replacement .........................
Holding switch alignment check ....
Tap changer contact wear .............
Direct-drive tap changers ...............
Drive mechanism .............................
Operational sequence .....................
Service and troubleshooting ............
Contact inspection .........................
Tap changer inspection ..................
Troubleshooting .............................
Replacement of tap changer parts .
Contact replacement .....................
Main and reversing movables .....
Main and reversing stationaries ..
Motor replacement .........................
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11
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13
Tap changer replacement ..............
Removal .........................................
Reinstallation ..................................
Retrofitting a new tap changer .......
Position indicator system .............
Internal drive shaft replacement ....
Extemal drive shaft replacement ....
Spare parts ......................................
Spare parts list .................................
!
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WA R N I N G / C A U T I O N :
Disregard of a WARNING or Caution
may result in serious personal injury and/or
serious damage to the equipment.
INSTRUCTlONS
These instructions apply to Distribution Vol-
tage Regulators. Read these instructions
carefully before attempting to use the voltage regulator.
The equipment covered by these instructions should be operated and serviced only
by competent personnel familiar with good
safety practices. These instructions are
written for such personnel and are not
intended as a substitute for adequate training and experience in safe procedures for
this type equipment.
The text of this instruction includes information concerning hazards to safety which
are common to all regulators. This safety
hazard information is offered for guidance
when installing and operating the descriptive matter to aid in preventing damage to
the equipment and to ad-
These instructions do not claim to cover all details or variations in the equipment, procedure, or process described, nor to provide direction for
meeting every possible contingency during installation, operation, or maintenance. When additional information is desired to satisfy a problem
not covered sufficiently for the user’s purpose, please contact your Cooper Power System's sales engineer.
March 1987 • New Issue (Replaces S225-10-3 (6/78) and S225-10-4 (6/78)
1
Spring-Drive and Direct-Drive Tap Changer Switches in VR-32
vise of possible hazards to personnel. When
reading this text, the meaning and content of
these statements should be understood and
followed carefully.
WARNING: Care must be exercised to avoid contact between live
parts and ground.
!
GENERAL
S225-10-2 covers operating, maintenance,
and replacement instructions for spring-drive
and direct-drive tap changers in Cooper
Power Systems VR-32 voltage regulators.
Use in conjunction with S225-10-1 or S22510-3. Starting in 1982 the type of tap changer
(spring or direct drive) for a specific regulator
rating was placed on the rating plate adjacent
to the wiring schematic. Older equipment will
require inspection to determine type of tap
changer furnished.
For many years Cooper Power Systems
has employed model numbers combined with
a letter suffix to identify interchangeability of
the tap changer within the design family.
Since January 1976, the model number has
been stamped into the front of the spring-drive
drive frame and top of the direct-drive lower
drive assembly. Figures 1 through 4 illustrate
the present generation of model numbers.
Regulators for low current applications use
spring drive model 928 for 95-kV BIL and
below and model 170 for 150-kV BIL.
Medium and high current applications use
direct drive models 770 and 660 for 150-kV
BIL and below.
Figure 1B.
928D spring-drive tap changer. (2000)
Motor
The motors for all tap changers are permanent split capacitor type suitable for operation
in both directions of rotation at 120Vac, singlephase, 50/60 Hz. An integral braking mechanism controls motor coast. All components are
compatible with hot transformer oil and the
windings are oil-cooled. The motor will carry
locked-rotor current for at least 3000 hours.
All motor capacitors are paper dielectric type
using a non-PCB dielectric fluid.
CAUTION: Do not operate motor
in air for excessive time or overheating and failure may result.
!
WARNING: Capacitor manufactures began phasing out PCB fluids
in the 1970s. All non-PCB capacitors are
clearly marked on the case. If not clearly
marked as non-PCB, replace capacitor
when servicing regulator.
!
Holding Switch
All tap changers are equipped with a holding
switch to assure that a tap change in process is
completed. This switch also provides a repetitive and accurate opening action causing the
motor brake to stop the drive components with
correct alignment. A signal from the
2
Figure 2B.
170C spring-drive tap changer. (2045)
S225-10-2
holding switch activates the operations
counter and prevents time delay reset during
a tap change.
On spring-drive tap changers the holding
switch is operated by a cam on the motor
shefl, see Figure 5.
On direct-drive tap changers the holding
switch operating cam is located above the
geneva gear on the top end of the main drive
shaft, see Figure 6.
The holding switch alignment and setting
shown in Figures 5 and 6 will assure coordination with the limit switches and drive components.
Contacts
All movable and stationary contacts employ
copper-tungsten or silver-tungsten tips at
points subjected to arcing duty. Contact
points not exposed to arcing employ acombination of ETP copper and silver to provide a
high conductivity current path. Movable contacts are split to make contact on both sides
of mating parts and resist separation during
high current surges. Contact pressure is
maintained by steel leaf or compression
springs. All contacts for current tap changer
models can be retrofit to older models.
Reversing Switch
Figure 3B.
Model 770B tap changer. (2100)
Figure 4B.
Model 660C tap changer. (2200)
The reversing switch changes the polarity of
the tapped winding. When the spring-drive
tap changer is in the neutral position, the
reversing switch is open (see Figure 6).
When the direct-drive tap changer is in the
neutral position, the reversing movable contact is in contact with the lower reversing stationary contact (VL) (see Figure 11). In both
arrangements the reversing switch is not in
the load current circuit.
The reversing switch motion on the springdrive tap changers occurs as the main movable contacts enter or leave the neutral position. A pin in the contact drive sprocket
engages a slot in the reversing segment
when the main switch is in the neutral position. The first tap step, in either direction,
rotates the segment and the reversing switch
to engage the appropriate reversing stationary.
The reversing switch motion, on the directdrive tap changers occurs as the main movable contact moves from neutral to the first
raise position or from the first raise position
to neutral. On Model 770 tap changers, a
roller on the back side of the rear roller plate
engages a slot in the reversing segment on
the reversing insulating arm. On Model 660
tap changers, a pinion, mounted on the same
shaftl as the rear roller plate, engages a slot
in the reversing segment of the reversing
insulating arm. As the rear roller plate rotates
CCW, the reversing movable contacts are
driven from the reversing stationary contact
(VL) to the reversing stationary contact (VR).
The reversing movable is also relocated on
the VL or VR reversing stationary when the
main movable contacts enter or leave positions 2 lower or 3 raise.
Spring-drive and direct-drive reversing
switches may be exposed to arcing duty.
3
Spring-Drive and Direct-Drive Tap Changer Switches in VR-32
MAINTENANCE
This discussion outlines maintenance procedures relating to regulator components other
than the control. Before any internal or external maintenance is performed, the regulator
must be removed from service.
It is necessary to open the regulator for
inspection, routine maintenance, and repair
when troubleshooting procedures, outlined in
S225-10-1 or S225-10-3, have isolated the
problem to an internal malfunction.
Refer to S225-10-1 or S225-10-3 for
1. Removing the regulator from the line.
2. Untanking and retanking procedures.
3. Connecting the regulator into service.
4. Power circuits.
CAUTION: The tap changer must
not be subjected to elevated temperatures above 150oF.
!
SPRING-DRIVE TAP CHANGER
Drive Mechanism
Figure 5.
Model 170 and 928 holding switch adjustment.
All spring-drive tap changer models employ
the same drive mechanism. A sprocket cam,
pin cam and actuator on a crank shaft are
progressively uncoupled and recoupled
through a pin that is transferred 180°. During
the transfer motion, the crank shaft is rotated
to top dead center and two steel extension
springs are loaded. The springs are
arranged in a triangular configuration to provide a positive “spring over center” action to
move the contact drive sprocket and contacts one position. A shock absorbing mechanism is integrated with the extension
springs to control contact speed and produce
a controlled make and break contact action.
A pin on the contact drive sprocket is positioned to provide a mechanical stop that prevents contact motion beyond the maximum
raise and lower positions.
Models 928 and 170 include an output
shefl to drive the position indicator flexible
drive shaft. On tap changers manufactured
after November 1975, the position indicator
output shaft is geared to the motor shaft.
One motor shaft revolution rotates the output
shaft 180° and advances the position indicator hand one position in a uniform continuous
motion. (Models 928A, 928B, 928C, 170A
and 170B).
On models 928D and 170C, which were
introduced in early 1986, the position indicator output shaft is geared to teeth on the
outer edge of the actuator. A 180o rotation of
the actuator rotates the output shaft 180o
and advances the position indicator hand
one position in a quick motion.
Operational Sequence
Figure 6.
Model 660 and 770 holding switch adjustment.
4
When the tap changer is in the neutral position, and the control calls for a tap change,
the following events occur:
1. Motor brake releases and motor starts.
2. Motor holding switch closes, assuring the
completion of one tap change.
S225-10-2
CAUTION: The control must be
deactivated by opening the disconnect switch "V1", and closing the CT shorting switch "C". Place the control and power
switches in the OFF position. The bushings
must be grounded.
!
CONTACT INSPECTION
Tap changer contacts are exposed to a combination of electrical, mechanical and thermal
conditions that result in deterioration. Erosion
at the points subjected to arcing duty is the
most visible indication of wear. Figure 7 illustrates typical contact erosion patterns resulting
from normal service. Analysis of the tap changer service history and contact erosion will
establish the schedule for future inspection or
replacement.
Contacts at the end of life stage shown in
Figure 7 must definitely be replaced. See
replacement instructions on page 6.
TAP CHANGER INSPECTION
Figure 7.
Typical contact erosion patterns.
3. The up slope of sprocket cam engages
the lip of the spool, lifting the pin in the
pin cam, and frees it of the hole in the
actuator.
4. A projection on sprocket cam engages
leg on pin cam and both tum.
5. Driveshaft, which is attached to pin
cam, begins to turn crank arm and
springs begin to extend.
6. Pin is freed from the lip on the spool
and a spring pushes it against surface
of actuator.
7. Down slope of sprocket cam retums
spool to start position.
8. Pin drops into hole in actuator 180 o
from start position.
9. At this point, the crank arm is at top
dead center and the springs are fully
loaded. Driveshaft, crank arm, sprocket
cam, pin cam, and actuator are locked
together and connected through the
chain to the motor.
10. The motor drives all parts beyond top
dead center.
11. Springs unload instantaneously, pulling
pin cam and actuator through 180° at
high speed. Pins on actuator cause
contact drive sprocket and contacts to
index one tap position.
12. As the contact drive sprocket moves, it
imparts motion to the reversing switchsegment and main movable contacts.
This action closes the reversing movaable and reversing stationary contacts
and drives the main movable contact
onto the adjacent main stationary contact. Also the neutral light switch opens.
13. Motor continues to tum sprocket and
holding switch cam until the motor holding switch opens and the brake is reapplied. The motor has completed one revolution.
14. Completion of actions 1 through 13 will
also move the position indicator output
shaft 180o and position indicator hand
one position. This motion is transmitted
through gearing on the motor shaft or
actuator.
Should more than one tap change be
required, the foregoing sequence will be
repeated (except reversing switch portion)
until the control is satisfied, or the limit
switch in the position indicator is reached.
Service and Troubleshooting
The following troubleshooting and servicing
functions are performed with the regulator
partially untanked as outlined in S225-10-1
Check all lead connections to the back of the
tap changer panel for security. Also check all
fasteners joining the panel, top and bottom
brackets and drive as well as the mounting
bolts.
The nuts securing the main movable contact
fingers to the insulating arm should be tight. In
some cases, the insulating arm is slotted and
has a recess into which the flat washer and nut
must seat.
The movable fingers on the reversing switch
should be tight and in line with the point on the
VL and VR stationary. The retainer ring at the
reversing switch pivot should be completely
seated in the groove.
The drive mechanism is expected to have a
mechanical life of at least 1,000,000 operations. Slight wear at the points of contact
between spool, pin and sprocket are nominal.
A polished area on the top surface of the spool
guide is also normal. All fasteners and wiring
connections should be tight and secure. Chain
tension will vary, but it should not be possible
to disengage it from the sprockets without disassembly. The holding switch alignment should
be as shown in Figure 5.
TROUBLESHOOTING
Tap changer trouble may be due to a mechanical blockage, loose or open connections or a
disabled motor. A thorough visual inspection
will help discover the problem.
1. Examine the insulating panel, contacts and
drive mechanism for signs of arcing
between the live parts and ground. Such
damage is usually related to a major fault
and may limit salvage of the regulator.
2. Note the position of the main and reversing
movables and driveline components. At
neutral, alignment should be per Figure 8.
At positions other than neutral driveline
alignment will be as illustrated but the
main and reversing movable fingers
should be fully engaged on the mating
stationary contacts. If these conditions
5
Spring-Drive and Direct-Drive Tap Changer Switches in VR-32
6. If the motor operates as outlined in #5,
check the entire tap changer. Lower the
internal assembly until the motor shaft
and holding switch are just covered with
oil. With power applied as described in
#5, operate the tap changer one step at a
time to 16 raise and 16 lower comparing
the position of all components with the
information in 2a, 2b and 2c and Figure 8
at the end of each step. One step will
take 10 seconds on tap changers manufactured before August 1981 and 5 seconds on newer models using the Von
Weise motor. At least three operations
are required to fill the dampers with oil
and obtain normal action.
CAUTION: Do not run mechanism to mechanical stop as this can
cause loss of synchronization between the
contact posotion and the position indicator
on models 928A, 928B, 928C, 170A and
170B.
!
Tap changer malfunctions are most likely
to occur during this testing and close observation is required to identify drive-line probems.
If tap changer operation is satisfactory, run
the mechanism to the neutral position (see
Figure 8) and disconnect power source.
Check that the position indicator is in agreement with the contact location. Realign if necessary by adjusting at the set screw coupling.
CAUTION: If the tap changer
malfunctions continue with no apparent cause, contact the factory for directions.
!
Figure 8.
Neutral position spring-drive tap changer.
are not found, a normal tap change
motion has not been completed and
the mechanism is probably jammed.
a. A main movable may have jammed
at the leading edge of the stationary
and will require replacement of the
damaged finger and realignment of
the contacts.
b. The reversing movable may have
jammed at the leading edge of the
stationary as a result of misalignment due to a bent stationary or
wear at the pivot. Either condition
will require replacement of the
reversing switch and realignment
of the stationary.
c. Examine the driveline components
for worn parts. Slight wear at the
points of contact between the pin,
spool and sprocket cam are normal. The pin should be fully seated
and engaging the actuator. A polished area on the top surface of
the spool guide is normal.
Excessive wear or a sticking pin will
require replacement of the drive. Special
instructions will be provided.
6
CAUTION: Any decision to
replace the drive should be deferred
until all checks and an operation test have
been completed.
!
3. Check all wiring to the terminal board,
motor, capacitor, neutral light and holding switch for loose or open connections. Tighten or repair as required.
4. Disconnect all leads from the capacitor
and check continuity between terminals. The meter should show initial continuity and then drop to zero. A steady
reading or no initial reading indicates
the capacitor is defective. Replace with
the same rating (see case markings).
5. Check the motor by connecting a 120
Vac supply directly to the tap changer
terminal board.
For models 170 and 928:
Place the ground lead on the “G” terminal.
Place the hot lead on TCB4 for raise
operation. (CCW)
Place the hot lead on TCB5 for lower
operation. (CW)
If the motor will not operate and move the
drive and contacts in both directions it
should be replaced.
REPLACEMENT OF TAP
CHANGER PARTS
CAUTION: It is recommended
that the tap changer be removed for
all major work. See page 14 for instructions
on tap changer removal and reinstallation.
!
contact replacement
Remove the insulating panel that contains all
contacts from the drive. Note the positions of all
metal washers and insulating spacers for proper reassembly.
Main Movables
1. Remove the nuts and washers holding the
movable contact fingers to the insulating
arm and lift the arm free of the contact
studs and front slip ring post.
2. Slide the contacts free from the stationary
and slip rings and remove.
3. Slide the new contacts onto the slip rings
and stationary contact. The right hand
movable finger must engage the front slip
ring. Align the contact studs with the holes
in the insulating arm and position the arm
on the studs and front slip ring post.
S225-10-2
CAUTION: On slotted and
recessed arms the studs must be at
the inner end of the slots.
!
4. Place the washers over the contact
studs. When a slot and recess is present the washers must be fully seated
in the recess.
5. Place a drop of Loctite #242 on each
stud and tighten the nuts securely.
6. The slip ring end of the contact fingers
should be adjusted to lay flat on the
surface of the slip ring. The insulating
arm should move freely on the front
slip ring post. The contact fingers
should engage all stationary contacts
smoothly from both directions.
Main Stationaries
1. Place the movable contacts on another
position and remove the hardware from
the back side of the contact panel.
2. Insert contact pins through contact
panel and replace hardware; tighten all
nuts securely.
3. Check alignment of the surface plane
with other contacts. See Figure 9 for
correct contact height.
CAUTION: The alignment ofthe
surface plane with other contacts is
essential for proper matting with the
moveable contacts. Poor alignment can
damage the contact and jam the tap
changer. If necessary, bend the contact
body to produce alignment.
!
4. Repeat steps 1, 2, and 3 for each contact requiring replacement.
5. The movable contact fingers should
engage each stationary smoothly from
both directions.
Reversing Switch
1. Remove the retainer ring from the
reversing switch pivot post.
2. Disconnect the flexible lead from the
neutral stationary.
3. Lift reversing switch body free of post
and pull flexible lead through the panel.
4. Remove all shims from post except 1/16”
brass washer should remain in recess
in panel.
5. Slide new reversing switch body onto the
pivot post and insert lead through panel.
6. Use shims between body and retainer
ring to control wobble.
7. Place flexible lead on stud of neutral stationary and secure.
8. Rotate body to check alignment at VR
and VL stationary contacts. Movable finger tips should be centered on the point
of the stationary. Bend the stationary to
suit.
CAUTION: Replacement of VR
and VL stationary contacts or slip
rings is rarely required. Cleaning will suffice.
!
Reassemble panel to drive with care to
place all metal washers and insulating spacers at locations noted during disassembly.
All components should be aligned as shown
in Figure 8.
1. Slide the insulating arm slots over the
two drive fingers.
2. Install top and bottom bolts snug and
check vertical and horizontal alignment
of drive and panel.
Contact circle must be centered on the
contact drive sprocket.
3. Tighten the mounting bolts securely.
4. Connect the 120-Vac supply directly to
the tap changer terminal board.
For Models 170 and 928:
Place the ground lead on the “G” terminal.
Place the hot lead on TCB4 for raise
operation (CCW).
Place the hot lead on TCB5 for lower
operation (CW).
5. Run the tap changer to each mechanical stop to assure free operation. Each
step will require 5 to 10 seconds
depending on age of the tap changer.
Return the tap changer to neutral as shown
in Figure 8. The tap changer is now ready to
be installed in the regulator.
MOTOR REPLACEMENT
Spring-drive tap changers manufactured
prior to August 1981 employed a motor that
was mounted to the underside of the top
plate on the drive. Typical tap changer models (when model number used) are 170A,
928A, and 928B. This motor has been discontinued but can be replaced with motor
code #2001. MEPS will furnish a special
motor replacement kit including all required
hardware, wiring diagrams and instructions.
The regulator serial number or tap changer
model number, when available, will help
identify the age of the equipment.
Since August 1981, the tap changer motor
has been mounted on a support bolted to
the drive frame or a shelf formed into the top
bracket. The following instructions apply
only to motors so mounted.
In october 1985, Cooper Power Systems
implemented a significant change in motor
wiring to eliminate an undesirable ground
loop circuit. These instructions assume all
motor replacement will comply with the new
wiring method.
FOR MODELS 170 AND 928:
1. Cut the tie wraps securing the paper
tube containing the red and blue motor
to capacitor leads and disconnect those
leads from the capacitor.
2. Cut the white motor lead at a point just
below the paper tube through the top
plate.
3. Disconnect the motor white lead from
the G terminal or frame ground, pull
free and discard. Also eliminate any
jumper between the frame ground and
G terminal.
4. On some tap changers, the position indicator drive is geared to the motor shaft
Remove the indicator drive assembly
from the top plate.
other types of indicator drives need not
be removed.
5. Remove the four top plate securing bolts
and slide the plate to the right, being
careful not to damage the holding switch.
Set the plate off to the right.
6. Locate the master link in the chain and, if
accessible, remove it and take the chain
off the sprockets.
If the link cannot be removed, remove
the motor sprocket and indicator gear
(where employed) from the motor shaft,
using a 3/32 or 1/8-in.-diameter punch to
drive out the pins holding these parts.
7. Remove the motor mounting bolts.
8. Remove the freed motor by sliding the
gear and sprocket from the motor shaft
and removing the chain.
A replacement motor package is furnished containing all terminals, an insulating tube, and tie wraps.
(1) The sprocket will be in place and
aligned for the holding switch.
(2) The indicator drive gear must be
removed from the original motor (when
required) and installed on the new
motor.
9. Insert the motor red and blue leads
through the insulating tube and attach a
push-on terminal to each one.
10. Position the motor on the mounting shelf
with the sprocket in line with the sprocket
cam.
Replace and tighten the mounting bolts.
11. Position the driveline components and
contacts as shown in Figure 8. It may be
necessary to remove the springs from the
crank arm to obtain this alignment.
12. Replace the chain. The master link should
be located in the open space just below
the mounting shelf with the retainer on
the motor side.
Figure 9.
Contact height.
7
Spring-Drive and Direct-Drive Tap Changer Switches in VR-32
Figure 10.
Spring-drive internal wiring diagram.
8
S225-10-2
13. Replace the top plate, being careful not
to damage the holding switch.
a. Tighten the bolts finger-tight.
b. Check the alignment of the holding
switch and motor as shown in Figure
5.
c. Tighten bolts securely.
14. Push the motor white lead through the
paper tube in the top plate, install ring
tongue connector and connect to G terminal.
15. Connect all motor and capacitor leads
according to the wiring diagram Figure
10.
Use insulating tubes and tie wraps to
secure the motor and the capacitor
leads to the drive frame.
16. Where employed, replace indicator gear
and bearing-and-driveshaft assembly.
17. Apply 120 Vac and run the tap changer
to each mechanical stop to check the
holding switch operation at the mechanical stop. See Figure 5 and holding
switch alignment check below.
Place the ground lead on the G terminal.
Place the hot lead on TCB4 for raise
operation (CCW).
Place the hot lead on TCB5 for lower
operation (CW).
Return tap changer contacts to neutral,
as shown in Figure 8.
HOLDING SWITCH ALIGNMENT CHECK
1. Remove the junction box cover and open
the control box.
2. Connect a 120 Vac source to the external
source terminals on the face of the front
panel and set the control power switch
for external operation.
3. Set the control switch to “raise” and run
the tap changer until the position indicator shows 16R.
4. Turn the control and power switches to
the “off” position.
5. Place a jumper between terminal R in the
junction box and terminal R1 on terminal
strip TB1 on the back panel of the control box. (This bypasses the raise limit
switch). Also, place jumper between L
and L1 to bypass lower limit switch.
6. Set the control power switch to external
and the control switch to “raise”. The tap
changer will now run to the mechanical
stop, (past 16R).
7. Turn the control switch to “lower”. The
tap changer should back-off of the
mechanical stop as evidenced by the
position indicator pointer moving in a
lower direction toward "O".
If the tap changer does not back-off,
the holding switch is out of adjustment.
Adjust per Figure 5, or contact the factory for assistance. If it does back off, the
neutral light on the control will glow
when the Pl does not show neutral if the
tap changer and the positon indicator
are out of sync. This can only happen
with tap changers produced before
1986.
8. Allow the tap changer to continue run
ning in the lower direction until it reaches
the mechanical stop.
9. Turn the control switch to the “raise” position. The tap changer should run in the
raise direction toward "O". If the tap
changer doesn’t back off, the holding
switch is out of adjustment. Adjust per
Figure 5. If it does back off, proceed as
follows:
10. Stop the tap changer at 14L. If the tap
changer and position indicator had been
out-of-sync only one step, they are now
in sync. Set the control switch on lower. If
the tap changer and position indicator
had been out of step more than one step,
the tap changer will again hit the
mechanical stop when run to the end.
The tap changer must be operated
against the mechanical stop one time to
each step that it had been out of step in
order to put it back in step. If the tap
changer and Pl are synchronized, proceed to Step 11.
11. Turn the control switch to the “raise” position and run the tap changer to the ``o,,
or neutral position; the neutral light
should come on.
12. Turn the control and power switches to
the “off” position and disconnect external
power.
13. Remove both jumpers.
14. Replace the junction box cover and close
the control box.
TAP CHANGER CONTACT WEAR
The life of any voltage regulator, under normal
operating conditions, is primarily determined
by that of two components, the coil and the tap
changing mechanism. As in the rest of the
transformer industry, it is generally accepted
that the life of a regulator should be 20 to 30
years. However, it is well understood that
these life figures can only be achieved with the
aid of an effective preventative maintenance
program. The Cooper Power Systems voltage
regulator is designed to meet this criteria. This
means that all components, including the
mechanism, will give satisfactory performance
for this period of time provided that they are
properly maintained. Cooper Power Systems
recommends that the tap changing mechanism be inspected after 100,000 operations or
four years service, whichever comes first. At
this time, an appraisal should be made of the
condition and wear of both the movable and
stationary contact. From this appraisal, a
schedule for periodic inspection should be
established. These recommendations are
made based on the belief that effective preventative maintenance requires that it be
assertained during the first years of operation
whether any abnormal conditions exist within
the unit. If the only concern were the mechanism contacts, then it would be possible to
delay this inspection to from 10 to 30 years
depending on rating of the device. Cooper
Power Systems believes, and is supported by
the maintenance history of this device, that all
components meet the requirements of the
electric power industry.
DIRECT DRIVE TAP CHANGER
Drive Mechanism
All direct-drive tap changer models employ
drive mechanisms based upon the same
design principle and many components are
interchangeable. The motor turns a geneva
pinion three complete revolutions per tap
change. The motion of the geneva pinion
turns a six-tooth geneva gear, a main driveshaft, and a scroll cam 180o per tap change.
Each 180o movement of the scroll cam operates one of two roller plates and moves the
corresponding main movable contacts. The
combination of geneva gear and scroll cam
characteristics results in a three-step, wipetransfer-wipe contact action. Attached to the
main (geneva gear) driveshafl is a planetarygear-type mechanical stop/sthat prevents
contact motion beyond the maximum raise
and lower positions.
The top of the main driveshafl is the output
to the position indicator flexible drive shaft.
180o rotation advances the position indicator
hand one position in three start/stop motions.
Operational Sequence
When the tap changer is in neutral and the
control calls for a tap changer in the raise
direction, the following events occur:
1. Motor brake releases and motor starts.
2. Geneva pinion rotates counterclockwise
to engage geneva gear.
3. Geneva pinion drives the geneva gear,
main drive shefl, and scroll cam through
60o and produces initial wipe action at
the front main movable contact and
reversing movable contacts.
4. The motor holding switch closes, assuring that one tap change will be completed.
5. The geneva pinion completes first revolution and continues to rotate.
6. The geneva pinion drives geneva gear
through 60o and the scroll cam and roller
plate transfer the front main movable contact from the neutral stationary contact N
to the stationary contact No. 1.
Simultaneously, the reversing movable contact is transferred from the reversing
stationary contact (VL) to the stationary
contact (VR).
7. The neutral light switch opens.
8. The geneva pinion completes second
revolution and continues to rotate.
9. The geneva pinion drives geneva gear,
main drive shefl, and scroll cam through
60o and produces final wipe action at
the front main movable and reversing
movable contacts.
10. The motor holding switch opens.
11. The motor brake engages.
12. The motor stops.
A tap change from No. 1 raise position to
neutral will be accomplished as described
except the geneva pinion will rotate clockwise. The reversing movable contact will be
transferred from the reversing stationary contact (VR) to the stationary contact (VL).
9
Spring-Drive and Direct-Drive Tap Changer Switches in VR-32
Should more than one tap change be required,
the foregoing sequence will be repeated (except
reversing switch portion) until the control is satisfied, or the limit switch in the position indicator is
reached.
Service and Troubleshooting
The following troubleshooting and servicing functions are performed with the regulator partially
untanked as outlined in S225-10-1 or S225-10-3.
CAUTION: The control must be
deactivated by opening the disconnect switch "V1", and closing the CT shorting
switch "C". Place the control and the power
switches in the OFF position. The bushings
must be grounded.
!
CONTACT INSPECTION
Tap changer contacts are exposed to a combination of electrical, mechanical and thermal
conditions that result in deterioration. Erosion at
the points subjected to arcing duty is the most
visible indication of wear. Figure 7 illustrates typical contact erosion patterns resulting from normal service. Analysis of the tap changer service
history and contact erosion will establish the
schedule for future inspection or replacement.
Contacts at the end of life stage shown in
Figure 7 must definitely be replaced. See
replacement instructions on page 6.
TAP CHANGER INSPECTlON
Check all lead connections to the back of the
tap changer panel for security. Also check all
fasteners joining the top and bottom drive elements as well as the mounting bolts.
The bolts securing the main and reversing
stationary contacts should be tight. Also, the
main and reversing movable contacts should be
securely attached to the insulating arms.
The drive mechanism is expected to have a
mechanical life of at least 1,000,000 operations.
Slight wear at the points of contact between
geneva and pinion are normal. All fasteners and
wiring connections should be tight and secure.
The holding switch alignment should be as
shown in Figure 6.
The slope portion of the scroll cam will normally show visible wear at less than 50,000
operation. This condition does not interfere with
the drive action.
TROUBLESHOOTING
Tap changer trouble may be due to a mechanical blockage, loose or open connections or a
disabled motor. A thorough visual inspection will
help discover the problem.
1. Examine the insulating panel, contacts and
drive mechanism for signs of arcing
between the live parts and ground. Such
damage is usually related to a major fault
and may limit salvage of the regulator. Note
that the lower drive element is normally at
line potential and the top element is
grounded.
2. Note the position of the main and reversing
movables and driveline components. At
neutral, alignment should be per Figure 11.
At positions other than neutral,
10
driveline alignment will be as illustrated
but the main movable fingers should be
fully engaged on the mating stationary
contacts. If these conditions are not
found, a normal change motion has not
been completed and the mechanism is
probably jammed. A main or reversing
movable may be jammed at the leading
edge of the stationary due to loose contact parts. If no looseness is found, additional checking is required to isolate the
cause.
3. Check all wiring to the terminal board,
motor, capacitor, neutral light and holding switch for loose or open connections. Tighten or repair as required.
4. Disconnect all leads from the capacitor
and check continuity between terminals. The meter should show initial continuity and then drop to zero. A steady
reading or no initial reading indicates
the capacitor is defective. Replace with
the same rating (see case markings).
5. Check the motor for free rotation. An
internal brake must be released to permit motor rotation:
a. Insert the tip of a screwdriver
between the two gears on the motor
shaft and pry gently to push the
smaller gear and shaft down approximately 1/16-in. to free the brake and
permit a small amount of rotation in
both directions of the geneva pinion,
gearing and the motor.
b. If the motor brake will not release or
the motor does not turn freely, it
should be considered defective. See
page 13 for replacement instructions.
6. If brake action is satisfactory, remove the
geneva pinion by removing a retainer
ring at the top or set screws in the side.
7. Check the motor by connecting a 120
Vac supply directly to the tap changer
terminal board. For models 770 and
660:
Place the ground lead on the “G” terminal.
Place the hot lead on TCB4 for raise
operation. (CCW)
Place the hot lead on TCB5 for lower
operation. (CW)
If the motor wili not operate, it should be
replaced. See page 13 for instructions.
8. If the motor operates as outlined in #7
check the drive elements. Remove the
position indicator flexible drive shaft
from the tap changer. Manually rotate
the geneva to determine if the contacts
will complete a tap change in both directions. Any dragging or binding may be
due to damaged contacts, broken insulating arms or loose parts. If no defects
are found, turn the geneva to place the
mechanism in neutral as shown in
Figure 11. Stop the geneva with the pinion recess centered on the intermediate
shaft.
9. Place geneva pinion on intemmediate
shaft with roller pointing away from
geneva and set screw aligned with
spline slot in the shaft. Slide pinion
down to engage the geneva; hold the
shaft up to eliminate all vertical play
on the shaft and tighten set screws.
10. With power applied as described in
#7, operate the tap changer one step
at a time to position 3 raise, comparing the position of all components
with the information in #2. If satisfactory, run to 2 lower with same procedure.
11. If motor and drive operation are satisfactory, run to lower mechanical stop
and check holding switch alignment
per Figure 6.
12. Check the total running time from the
lower mechanical stop to the raise
stop. Time should be 41 to 43 seconds. Excessive time is typical of
problems that require factory repair.
Contact MEPS for instructions.
13. If time running raise is within limits,
run to lower stop to check total time.
Check the holding switch alignment
per Figure 6. Return the tap changer
to neutral per Figure 11 and reconnect the position indicator shaft to the
tap changer.
!
CAUTION: If the tap changer
malfunctions continue with no
apparent cause, contact the factory for
directions.
REPLACEMENT OF TAP
CHANGER PARTS
!
CAUTION: It is recommended
that the tap changer be removed
for all major work. See page 14 for
instructions on tap changer removal and
reinstallation.
S225-10-2
CONTACT REPLACEMENT
Main and Reversing Movables
REMOVING OLD CONTACTS
1. Run the tap changer to the neutral position, see Figure 11 for the neutral-position relationship.
2. Remove the geneva pinion.
3. Move the switch contacts by rotating the
geneva gear counterclockwise until both
main movable contacts are on
Stationary Contact 8 (see identification
mark on end of studs).
4. Remove all stud-end hardware fastening
the Stationary Contact 7 to the insulating
panel.
5. Pull the contact assembly out until it is
free to turn. Rotate the assembly 180°
and pull free of the panel being careful
not to lose any fiber pins, standoff collars or insulating tubes. Note location of
parts for reference at assembly.
6. Turn the geneva gear counterclockwise
to move the rear movable contact into
the space vacated by Contact 7.
7. Remove the two bolts holding the rear
movable contact assembly to the insulating arm; slide the contact assembly free.
8. Turn the geneva gear counterclockwise
to move the front movable contact to the
space vacated by Contact 7.
9. Remove the two bolts holding the front
movable contact assembly to the insulating arm; slide the contact assembly free.
10. Remove the two bolts fastening the
reversing movable contact to the insulating arm. Rotate the geneva gear to position the bolts for access.
11. Rotate the geneva gear clockwise until
the reversing movable contact is centered between reversing stationary contacts VR and VL: slide the movable contact assembly vertical until free.
INSTALLING NEW CONTACTS
Replacement movable contact assemblies
are fumished ready to install.
12. Slide the reversing movable assembly
into the slot in the reversing insulating
arm and the button contact end onto the
neutral stationary contact using a 1/4 to
5/16-in.-diameter dowel to spread the
button contacts as shown in Figure 12 to
allow for a smooth engagement onto the
neutral stationary.
13. Remove the dowel.
14. Install two bolts, washers, and nuts; tighten securely. Rotate geneva gear to
check alignment of movable with VL and
VR stationary contacts. The gap
between the movable tips must be centered on the point of the stationary. If
necessary, bend stationary slightly to
produce this alignment.
15. Rotate geneva gear to move the front
insulating arm into the vacant #7 space.
Figure 11.
Neutral position direct-drive tap changer.
Figure 12.
Button contact.
11
Spring-Drive and Direct-Drive Tap Changer Switches in VR-32
16. Slide the main movable assembly into
the slot in the front insulating amm and
the button contact end onto the front
slip ring using a 1/4” to 5/16” diameter
dowel to spread the button contacts as
shown in Figure 12 to allow for a
smooth engagement onto the slip ring.
17. Remove the dowel.
18. Install two bolts, washers and nuts;
tighten securely.
19. Place the rear movable contact insulating arm in the Contact 7 space.
20. Slide the main movable assembly into
the slot in the rear insulating arm and
the button contact end onto the rear
slip ring using a 1/4” to 5/16” diameter
dowel to spread the button contacts as
shown in Figure 12 to allow for a
smooth engagement onto the slip ring.
21. Remove the dowel.
22. Install two bolts. washers and nuts;
tighten securely.
23. Rotate the geneva gear clockwise until
the tap changer is in the neutral position as shown in Figure 11.
24. Install stationary contact assembly #7
making sure the front standoff collar,
fibre pins, insulating tube and contact
base are aligned to position the blades
to the inside.
a. on the 660, the flat side of the rear
standoff collar must be against the
back side of the insulating panel
and the slots on the opposite side
aligned vertically.
b. on the 770. the slot in the rear
standoff collar must be against the
back side of the insulating panel
and aligned vertically.
c. Tighten stud end hardware securely.
25. Rotate geneva to move main contacts
through all positions. The movables
should smoothly engage the stationaries from both directions. No alignment
adjustment is required.
26. Connect a 120 Vac supply directly to
the tap changer terminal board.
Place the ground lead on the “G”
terminal.
Place the hot lead on TCB4 for raise
operation. (CCW)
Place the hot lead on TCB5 for
lower operation. (CW)
a. Check total running time from
mechanical stop to opposite side
stop running both directions. Time
should be 41 to 43 seconds.
b. Stop mechanism in neutral as
shown in Figure 11.
!
CAUTION: Fasteners may be
secured with lockstrips. DO NOT
REUSE LOCKSTRIPS. Discard and
replace with steel split lockwashers.
Insulating parts must be protected with a
flatwasher.
12
Main and Reversing Stationaries
REMOVING OLD CONTACTS
1. Remove both main and reversing movable contacts as explained on page 11
1 through 11.
2. Remove the bolts holding the VL and VR
reversing stationary contact blades in
place.
3. Remove the fasteners securing the front
insulating panel to the rear insulating
panel at the top.
a. On the 660, remove the nuts and
washers fastening the front insulating
panel to the reversing stationary contact stud.
b. On the 770, remove one of the bolts
fastening the standoff collar, capacitor bracket, and both insulating panels to the cast drive bracket.
!
CAUTION: To avoid misalignment
in the drive mechanism, do not loosen
both bolts at the same time.
Install a 3/8" x 1-1/2-in.-long bolt and
nut to fasten the capacitor bracket
panel, and cast drive bracket securely together. Repeat Step 3b for the
second bolt.
4. Remove the bolts fastening the front insulating panel to the mounting brackets
and lift the panel, complete with drive
mechanism, capacitor, and terminal
board free.
Set this assembly aside, being careful
not to damage the movable contact
insulting arms or panel.
5. All stationary contact assemblies can now
be removed from the rear insulating
panel by removing the stud-end hardware being careful not to lose any fibre
pins, standoff collars or insulating tubes.
Note position of parts for reference at
assembly.
a. Note the sequence of contact numbers on the end of the stud for
reassembly in the proper position.
b. All stationary contact assemblies can
now be completely disassembled by
removing the bolts or nuts.
c. The non-arcing contact blade from the
neutral stationary should be retained.
Replacement of this contact or slip
rings is rarely required. Cleaning will
suffice.
INSTALLING NEW CONTACTS
6. Reassemble the stationary contact
blades, keeping them square with the
body of the stud and each other; tighten
bolts and lockwashers securely.
7. Place all stationary contact assemblies in
the proper position, except Contact 7 and
the VL and VR blades. Position the
standoff collars, fibre pins and insulating
tube at locations previously noted.
a. on the 660, the flat side of the rear
standoff collar must be against the
back side of the insulating panel
and the slots on the opposite side
aligned vertically.
b. On the 770, the slot in the rear
standoff collar must be against the
back side of the insulating panel
and aligned vertically.
c. Tighten stud end hardware securely.
8. Adjust the non-arcing contact of the neu
tral stationary assembly so that the flat
surface of the bottom portion is parallel
to the top edge of the rear insulating
panel.
a. Raise the contact to eliminate slack
at the bolts.
b. Tighten nuts and lockwashers
securely.
9. Slide the front insulating panel and attached components over the non-arcing contact on the neutral stationary.
a. On the 660, the panel must engage
the reversing stationary contact
studs.
b. On the 770, the panel must fit
between the reversing stationary
contact studs.
10. Install the hardware fastening the front
insulating panel to the mounting brackets and tighten securely.
11. Replace the fasteners securing the front
and rear insulating panels at the top.
a. On the 660, place the flat washer,
lockwasher and nut on the reversing
stationary contact studs and tighten
securely.
b. On the 770, remove one of the temporary 3/8 x 1-1/2 in. Iong bolts
installed in Step 3b.
!
CAUTION: To avoid misalign-
ment in the drive mechanism, do
not loosen both bolts at the same time.
1 2. Install a 3/8 X 5-1/2 in. Iong bolt
through the bracket, rear insulating
panel, standoff collar, capacitor
bracket, front insulating panel and the
drive bracket, tightening securely
while maintaining the alignment of the
angle bracket with the second hole in
the rear insulating panel. Align slots
in standoff collar vertically.
13. Remove the second temporary 3/8 X
1-1/2 in. Iong bolt and install the second 3/8 X 5-1/2 in. Iong bolt and
standoff; tighten securely.
14: Install the VL and VR contact blades
and tighten the bolts finger tight.
a. Use a straight edge to align the top
edge of both blades horizontally.
Tighten bolts securely while maintaining this alignment.
b. The face of both contacts must be
vertical and in the same plane.
15. Install all movable contacts per
instructions 12 through 25, pages 11
and 12.
S225-10-2
16. The button end of the reversing movable contact must run in a line parallel
to and approximately 3/16-in. from the
curved top edge of the non-arcing neutral stationary contact. If necessary,
bend the non-arcing contact up or down
to produce this condition.
17. Connect a 120 Vac supply directly to the
tap changer terminal board.
Place the ground lead on the “G” terminal.
Place the hot lead on TCB4 for raise
operation. (CCW)
Place the hot lead on TCB5 for lower
operation. (CW)
a. Check total running time from
mechanical stop to opposite side
stop running both directions. Time
should be 41 to 43 seconds.
b. Stop mechanism in neutral as shown
in Figure 11.
MOTOR REPLACEMENT
Direct-drive tap changers manufactured
prior to February, 1980 employed a four wire
motor and a 20 MFD, 370 volt capacitor in a
rectangular or oval case. This equipment is
no longer available and has been replaced
by a three wire motor using a 25 MFD, 370
volt capacitor in an oval case. In October
198S, Cooper Power Systems implemented
a significant change in motor wiring to eliminate an undesirable ground loop circuit.
These instructions assume all motor
replacement will comply with the new wiring
method.
REMOVING OLD PARTS
1. Disconnect from the temminal board the
white wire between the top fame ground,
located on the motor side of the top
drive element, and the “G” terminal. Do
not disconnect at fame ground end.
2. Disconnect fom the temminal board the
white wire between the bottom frame
ground, located on the left side tap
changer mounting bracket, and the “G”
terminal. Do not disconnect bottom
frame end.
3. Cut off the terminals of these two wires
and splice together. Insulate the splice
with oil proof tape. This should effectively ground the top drive element to the
main coil top core clamp.
4. Cut the white motor lead at the terminal
of the top frame ground. Do not disconnect the fame ground terminal.
5. Disconnect the motor and capacitor
wiring.
a. On rectangular case 20 MFD capacitor and four wire motor, remove the
old capacitor and all wires between
it, the motor and temminal board.
b. On oval case 20 MFD capacitor and
four wire motor, pull the push-on
connectors fom the capacitor. Leave
the red capacitor to temminal board
wire in place in the wiring bundle.
Loosen the capacitor mounting
strap and remove the capacitor.
c. On oval case 25 MFD capacitor
and three wire motor, pull the
push-on connectors from the
capacitor. If the capacitor is
defective (see page 10, step 4)
loosen the capacitor mounting
strap and remove the capacitor.
6. Remove the three bolts securing the
motor to the top drive element and
drop the motor free.
a. Remove the intermediate gear
and wear washer from the shaft
and retain for reassembly.
b. On the 770, remove the insulating shield and retain for
reassembly.
INSTALLING NEW PARTS
The motor replacement kit will include all
hardware and connectors required for all
conditions listed in 5a, 5b and 5c. The
motor leads will provide wire to complete all
connections.
!
CAUTION: Fasteners may be
secured with lockstrips. DO NOT
REUSE LOCKSTRIPS. Discard and
replace with steel split lockwashers.
Insulating parts must be protected with a
flatwasher.
7. On model 770, install the insulating
shield on the motor and secure all fasteners.
8. Place the wear washer on the intermediate shaft and set the intermediate gear
in place. Push the motor shaft down to
release the brake and rotate the intermediate gear one full turn to check for
binding.
9. Position the motor vertically with the
intermediate gear in mesh with the output gear and slide the intermediate gear
shaft into the hole in the top drive bracket.
10. Install the mounting bolts and lockwashers; tighten securely.
11. Mount the capacitor. It will be necessary
to break off the tabs on the left edge of
the capacitor mounting plate (facing
motor side of drive) to allow the 25 MFD
capacitor to extend to that side. The
capacitor terminals should project to the
right with the case lip against the tabs
on that side as shown.
a. Replacing a rectangular capacitor
with an oval capacitor requires the
use of a special strap and hardware
as shown in Figure 13. Temporary
dismounting of the current transformer may facilitate this work.
b. Replacing an oval capacitor does not
require special parts. The capacitor
can be secured with the original
strap and hardware.
12. Slide the 3/8dia. x 9” long paper tube
over the three motor leads until stopped
by motor. Train leads to top of motor
and secure to mounting boss with a tie
wrap.
a. Train leads along edge of drive element and secure with a tie wrap
through the hole in the casting.
b. Train red and blue wires to the capacitor temminals, cut to length and
install push-on connectors.
Figure 13.
Installation of strap for oval capacitor.
13
Spring-Drive and Direct-Drive Tap Changer Switches in VR-32
c. When additional wiring is required
between the capacitor and terminal
board, the excess cut from the red
and blue motor leads should be
used. Cut to length and install a ring
tongue connector on the board end
and a push-on at the capacitor. The
blue wire must reach TCB4 and red
must reach TCB5.
d. Train the white wire to TCB G, cut to
length and install ring tongue connector.
13. Connect the motor, capacitor and terminal board per wiring diagram, Figure 14.
Secure all terminal board fasteners.
14. Connect a 120 Vac supply directly to the
tap changer terminal board.
Place the ground lead on the G terminal.
Place the hot lead on TCB4 for raise
operation. (CCW)
Place the hot lead on TCB5 for lower
operation. (CW)
15. Check total running time from mechanical stop to opposite side stop running
both directions. Time should be 41 to 43
seconds. Stop mechanism in neutral as
shown in Figure 11.
TAP CHANGER REPLACEMENT
Removal
To remove a spring-drive or direct-drive tap
changer,
l. Disengage the position indicator flexible
shaft from the tap changer.
2. Disconnect all position indicator and control leads from the terminal board.
3. Disconnect all main and reactor winding
leads from the tap changer.
a. The main contact leads are marked to
correspond to the stud identification
b. Place the hardware on the studs for
safe keeping.
4. Remove all coil lead positioning and
restraining devices attached to the tap
changer noting the position for reassembly.
5. Remove the mounting bolts fastening the
tap changer to the top core clamp and
lift free.
Reinstallation
1. Visually inspect the tap changer and
check all fasteners. Tap changer should
be in neutral per Figure 8 or Figure 11.
2. Place the tap changer on the top core
clamp in the approximate final position.
3. Connect all main and reactor winding
leads to the tap changer. The main contact leads are marked to correspond to
the stud identification.
4. Align the tap changer with the mounting
holes in the top core clamp, install the
bolts and tighten securely.
5. Connect all position indicator and control
leads to the terminal board.
6. Place all coil lead positioning and
restraining devices in locations previously noted and fasten securely.
14
7. Align position indicator hand at neutral and
connect the flexible drive shaft to the tap
changer.
a. Oider spring- and direct-drive tap changers employ a set screw coupling to connect to the output shaft on the tap
changer.
CAUTION: Flexible drive shaft
slack should be approximately 1/4inch after final tanking. A loose cover to side
channel joint will require adjustment to avoid
straining the shaft when lifting.
!
b. Model 928D and 170C spring drive tap
changers employ a square tubular
output shaft. A square end on the flexible drive shaft is inserted into the
tube. The shaft slack is self adjusting.
8. Lower the internal assembly into the oil
until motor is covered and perform operation check as instructed on page 4 of
S225-10-1 or S225-10-3.
9. Complete retanking procedure.
Retrofitting a New Tap Changer
Cooper Power System tap changers maintain
a high degree of interchangeability and can
retrofit to all equipment manufactured since
1970. Adaptation of control wiring may be
required depending on age. Required special
instructions will be provided with the new tap
changer.
S225-10-2
Figure 14.
Direct-drive internal wiring diagram.
15
Spring-Drive and Direct-Drive Tap Changer Switches in VR-32
POSITION INDICATOR SYSTEM
Starting in April 1980, the position indicator
flexible drive shaft system consists of an
extemal section between the indicator and terminal board sealing gland and an internal section from the gland to the tap changer, see
Figure 15.
The external flexible drive shaft is secured
to the position indicator shaft via a cotter pin
or set screw coupling brazed to the flexible
shaft. A gland shaft is brazed to the terminal
board end and provides grooves for two "O"
ring gaskets. This construction creates a
rotating pressure tight seal on the inside of
the gland sleeve portion of the terminal board.
The gland shaft position is maintained by
retainer rings.
The intemal flexible drive shaft is jointed to
the gland shaft on the extemal shaft by a cotter pin coupling brazed to the flexible shaft.
This joint is located immediately under the
junction box terminal board. A set screw coupling or square end fitting is brazed to the tap
changer end of the flexible drive shaft.
Internal Drive Shaft
Replacement
b. Model 928D and 170C spring-drive tap
changers employ a square tubular output shaft. A square end on the flexible
dnve shaft is inserted into the tube. The
shaft slack is self adjusting.
6. Connect a 120 Vac external power supply
to the control.
7. Run the tap changer manually to verify
alignment of the position indicator hand
and the neutral light. If correction is
required:
a. Stop the tap changer with the neutral
light on.
b. Disconnect the flexible shaft from the
back of the indicator.
c. Tum the indicator shaft to center the
hand at zero (neutral).
d. Reconnect the flexible shaft.
8. Run the tap changer to both raise and lower
extremes to check operation of the limit
switches and coordination with holding
switch.
9. Return the tap changer to the neutral position and disconnect the power supply.
10. Complete retanking procedure.
It is necessary to open the regulator to
replace the indicator drive shaft system.
1. Remove the cotter pin fastening the internal shaft to the gland shaft, see Figure
15.
2. Disconnect the intemal shaft from the
tap changer output shaft.
a. Older spring- and direct-drive tap
changers employ a set screw coupling to connect to the output shaft on
the tap changer.
b. Model 928D and 170C spring-drive
tap changers employ a square tubular output shaft. The square end on
the flexible drive shaft is inserted into
the tube.
CAUTION: When ordering a
new internal shaft measure the
overall length and specify that size and
end fitting type (set screw or square).
!
3. Place the cotter pin coupling end of the
new shaft on the gland shaft and install
cotter pin. Bend ends of pin around coupling to provide maximum clearance to
terminal board connections and wiring.
4. Tum the flexible drive shaft to place the
position indicator hand at the center of
the mark corresponding to the location of
the tap changer contacts.
5. Connect the Hexible drive shaft to the tap
changer.
a. Older spring- and direct-drive tap
changers employ a set screw coupling to connect to the output shaft on
the tap changer.
CAUTION: Flexible drive shaft
slack should be approximately 1/4inch after final tanking. A loose cover to
side channel joint will require adjustment
to avoid straining the shaft when lifting.
!
16
Figure 15.
Flexible drive shaft sealing gland.
S225-10-2
External Drive Shaft
Replaecement
1. Remove the cotter pin fastening the internal shaft to the gland shaft, see
Figure 15.
2. Use retainer ring pliers (heavy duty type)
to remove the retainer ring from the
inside end of the gland shaft.
3. Remove the junction box cover and dis
engage the flexible shaft from the position indicator shaft.
a. In early 1986, this joint was changed
to a set screw type coupling.
b. Older equipment employed a cotter
pin coupling.
4. From the junction box side pull the gland
shaft free of the gland sleeve.
5. Use retainer ring pliers (heavy duty type)
to slide the second retainer ring over the
gaskets and free of gland shaft.
CAUTION: The new shaft is
corrosion protected. Clean only with
dry cloth.
!
6. On the new shaft, slide one retainer ring
onto the gland shaft, over the gasket
grooves and position 1/8" from flexible
shaft end.
7. Install two "O" ring gaskets in grooves on
gland shaft. Apply a light coat of MOLY-
COTE M-77 paste to the gaskets and
shaft between the gaskets. Do not coat
beyond gaskets.
8. Insert the gland shaft into gland sleeve
from the junction box side, being careful not to damage gaskets. Seat retainer ring on the end of gland.
9. Place second retainer ring on inside
end of shaft and seat ring to within
1/32"of the end of gland sleeve. Rotate
drive shaft in both directions to assure
free movement. End play should not
exceed 1/32".
10. Rotate shaft to align hole in gland shaft
with cotter pin coupling on internal
drive shaft, keeping set screw at position indicator end at top. Install cotter
pin. Bend ends of cotter pin around
coupling to provide maximum clearance to terminal connections and
wiring.
11. Set position indicator hand at the center
of the mark corresponding to the location of the tap changer contacts.
12. Place the set screw coupling on the
position indicator shaft and tighten set
screw securely.
13. Connect a 120 Vac external power supply to the control.
14. Run the tap changer manually to verify
alignment of position indicator hand
and the neutral light. If correction is
required:
a. Stop the tap changer with the neutral
light on.
b. Disconnect the flexible shefl from the
back of the indicator.
c. Turn the indicator shaft to center the
hand at zero (neutral).
d. Reconnect the flexible shaft.
15. Run the tap changer to both raise and
lower extremes to check operation of
the limit switches and coordination with
holding switch.
16. Retum the tap changer to the neutral
position and disconnect the power supply.
17. Complete retanking procedure.
SPARE PARTS
When ordering replacement parts for your
Cooper Power Systems tap changer, provide the following information:
1. Regulator serial number (found on control
nameplate).
2. Quantity of each part required.
3. Part code number of each part (as shown
in Table 1).
4. Description of each part (as shown in
Table 1 ).
Figure 16.
928B and 170B Spring-drive tap changer replacement parts.
17
Spring-Drive and Direct-Drive Tap Changer Switches in VR-32
Figure 17.
770B Direct-drive tap changer replacement parts.
Figure 18.
660C Direct-drive tap changer replacement parts.
18
S225-10-2
Table 1
Spare Parts
•
•
•
•
Description
General parts
Cover gasket
Handhole gasket
Position indicator (complete)
Position indicator glass cover
Position indicator external drive cable
(not used on regulators without
junction box)
Position indicator internal drive cable
(provide total length of old cable in
inches) for direct-drive and spring
drive before 1986
Square-end internal drive cable
Oil-level sight gauge
Automatic pressure relief valve
Drain valve sampling device
Sampling device
Elevating structure
928D Spring-drive tap changer
170C Spring-drive tap changer
Spring-drive 928D and 170C
tap changer parts
Replacement motor kit A*
(with sprocket and pin)
Main movable contact right hand (rear) **
Main movable contact left hand (front) **
Main stationary contact
Reversing stationary contact
right hand * *
Reversing stationary contact left hand **
Reversing movable contact assembly—
928C&D
Reversing movable contact assembly—
170B&C
Holding switch assembly
Motor capacitor
Contact hardware kit
(complete tap changer)
Miscellaneous hardware
Reversing contact back-up spring
Reversing movable contact
Neutral light switch
770B Direct-drive tap changer
660C Direct-drive tap changer
Direct-drive 770B and 660C
tap changer parts
Replacement motor kit B
(use old shield)
Replacement motor shield
Main or reversing movable contact
Motor capacitor with
mounting hardware kit
Neutral light switch
770B Direct-drive
tap changer parts (only)
Main stationary contact
Reversing stationery contact
Reversing stationary neutral
contact (non-arcing)
Contact hardware kit (complete tap
changer)
Miscellaneous assembly hardware
660C Direct-drive
tap changer parts (only)
Main movable contact
Main stationary contact
Reversing stationary contact
Reversing stationary neutral
contact (non-arcing)
Reversing movable contact
Contact hardware kit (complete tap
changer)
Miscellaneous assembly hardware
Part Code No.
Reference Figure
1015
1016
1021
1022
1030
Not Shown
Not Shown
Not Shown
Not Shown
Not Shown
1031
Not Shown
1032
1040
1042
1043
1044
1901
2000
2045
Not Shown
Not Shown
Not Shown
Not Shown
Not Shown
Not Shown
Figure 1 B
Figure 2B
2001
Figure 16
2002
2003
2004
2005
Figure 16
Figure 16
Figure 16
Figure 16
2006
2007
Figure 16
Figure 16
2050
Figure 16
2008
2009
2010
Figure 5
Figure 16
Not Shown
2011
2030
2031
2032
2100
2200
Not Shown
Not Shown
Not Shown
Not Shown
Figure 3B
Figure 4B
2101
Figure 18
2102
2103
2108
Figure 17
Figure 17
Figure 17
2032
Not Shown
2104
2105
2106
Figure 17
Figure 17
Figure 17
2107
Not Shown
2111
Not Shown
2202
2203
2204
2205
Figure 18
Figure 18
Figure 18
Figure 18
2206
2207
Figure 18
Not Shown
2211
Not Shown
*Motor kits include motor, capacitor and hardware.
**When contact viewed from motor-side of tap changer.
19
Cooper Power Systems
Quality from
Cooper Industries
PO Box 2850, Pittsburgh, PA 15230