Voltage Regulators
Reference Specifications for Voltage
Regulator Maintenance
CONTENTS
Introduction......................................................................................1
Safety................................................................................................1
Unloading or MovingRegulaors................................2
Installing or Removing Regulators............................2
Replacing Fronts Panels...........................................2
Untanking..................................................................2
Maintenance and Inspections....................................3
Contact Erosion .......................................................4
Spring Drive Holding Switch.....................................5
Direct Drive Holding Switch......................................6
Field and Shop Test..................................................7
Electrical Clearances in Oil.......................................8
Introduction
This reference information has been prepared to assist
competent technicians in the maintenance and service of
Cooper Power Systems (CPS) Voltage Regulators. If
additional information is required, contact a factory
representative at:
Cooper Power Systems
Transformer Products Service Group
2300 Badger Drive
Waukesha, WI 53188-5951
(262) 547-3846 FAX (262) 896-2402
tpservicegroup@cooperpower.com
Safety
These instructions are not intended as a substitute for
proper training or adequate experience in the safe
maintenance and service of voltage regulators. Personnel
using this document should be fully acquainted with industryaccepted high and low voltage safe operating practices and
procedures for servicing electrical power system apparatus.
For more information regarding the installation, operation,
and service of Cooper Power Systems (CPS) voltage
regulators refer to CPS documents S225-10-5, CL2 or
CL2A; S225-10-4C,CL4C; S22510-10, CL5A-CL5E,
McGraw-Edison® VR-32 Regulator Control Installation,
Operation and Maintenance Instructions and Parts
Replacement Information.
Service Information
S225-50-15
Danger: Hazardous voltage. Contact with
hazardous voltage will cause death or
severe personal injury. Follow all locally
approved safety procedures when working around high
voltage lines and equipment.
WARNING: Become thoroughly familiar with
the regulator before servicing. Make sure you
understand the purpose and function of all
equipment and accessories. Wear any protective
clothing or equipment required. Use a hot stick for all
grounding, testing, disconnect, or reconnect operations.
Treat the transformer as energized until you are certain of
its condition. Failure to do so may result in severe
personal injury, death or property damage!
WARNING: Before installing, operating,
maintaining, or testing this equipment,
carefully read and understand the contents of
the manuals. Improper operation, handling or maintenance can result in death, severe personal injury, and
equipment damage.
These instructions do not claim to cover all details or variations in the equipment, procedure, or process described, nor to provide directions for meeting every possible
contingency during installation or maintenance. When additional information is desired to satisfy a problem not covered sufficiently for the user's purpose, please
contact your Cooper Power Systems Representative.
Nov. 2001 • New Issue
Printed in USA
1
Reference Specifications for Voltage Regulator Maintenance
Unloading
Warning: The cover may fracture if the cover
mounted lifting eyes are used to lift the entire
unit. Lift the entire unit only with tank-mounted lifting
lugs
When an overhead crane is used for unloading, the
regulator must be lifted by means of a sling and spreader
bar utilizing the tank-mounted lifting lugs. Do not lift the
entire unit with the lifting eyes on the cover. The
lifting eyes are only to be used to untank the internal
assembly that is attached to the cover.
Installing or Removing a Regulator in
Service
Danger: Closing the bypass switch with the
tap changer in any position other than neutral
will short-circuit part of the series winding. Before closing
the bypass switch, the regulator must be in neutral, the
control switch set to OFF and the motor circuit fuse
removed. Failure to do so may result in severe personal
infury, death or property damage.
Three check are recommended for checking to see if a
regulator in the neutral position when in service.
S225-50-15
Note: If a regulator bypass disconnect is used in
place of three separate switches, steps 5, 6, and 7 are
carried out in one operation.
Replacing Front Panel
Removing Panel
1. Place control (Auto/Remote-Off-Manual) switch in
OFF position.
2. Place power switch in the OFF position.
3. Open V1 knife switch (and V6 if present) on back
panel.
4. Remove the 6 Amp motor fuse.
5. Push closed the current shorting switch, C. This
shorts out the secondary of the regulator CT.
6. Pull open disconnect knife switch, V1, (and V6 if
present). This de-energizes terminal board TB2.
7. Loosen and remove control panel fanning strip from
TB2 (bottom of back panel). TB2 has two rolls of
screws. To remove the fanning strip loosen only bottom
roll, do not remove screws from bottom roll .
8. Disconnect front panel ground (green) lead from back
panel. Regulators with CL4 and CL5 Series controls will
have ground leads that connects from front panel to
back panel. CL2, CL2A and CL1s do not have ground
leads.
9. Remove front panel from hinges.
Replacement of Panel
1. The neutral night on the control panel is continuously
ON.
2. The position indicator- indicating pointer is pointing at
Zero
Zero.
3. Use an approved high voltage meter to check for
differential voltage between the Source and Load
bushings. If the regulator is in neutral the meter should
not indicate any differential voltage between the source
and load bushings.
Reverse above process.
10. Make sure all switches on replacement panel are
turn off and the 6 Amp motor fuse is removed.
11. Engage the front panel on enclosure hinges.
12. Connect front panel ground lead to back panel.
13. Insert fanning strip from front panel wiring harness
under TB2 terminal board screws.
14. Tighten screws on interconnecting terminal board.
15. Push closed the disconnect switch, V1 (and V6 if
present).
16. Pull open the current shorting switch, C.
De-energizing a Regulator
17. Replace 6 Amp motor fuse.
Once it has been established that the regulator is on
neutral, the following steps should be followed to deenergizing the regulator.
Untanking Regulator
1. Place control (Auto/Remote-Off-Manual) switch in
OFF position.
2. Place power switch in the OFF position.
3. Open V1 knife switch (and V6 if present) on back
panel.
4. Remove the 6 Amp motor fuse.
5. Close bypass switch.
6. Open Load (L) disconnect switch.
7. Open source (S) disconnect switch.
8. Open source-load (SL) disconnect switch, if available.
2
Warning: When the internal assembly is
lifted for inspection or maintenance, blocking should be
placed between the cover and the top of the tank to
keep the assembly from falling should the lifting
apparatus fail.
S225-50-15
Reference Specifications for Voltage Regulator Maintenance
Caution: Before untanking a regulator that
contains a thermometer, (1) lower the oil
level below the thermometer, then (2) remove the
thermometer well. Failure to do will result in damage to
the thermometer well and/or spillage of oil when the
internal assembly is lifted.
Caution: Do not suspend the control box
using the control cable.
1. Manually run tap changer to neutral, if possible. If
not, record position indicator reading before proceeding to
untank.
2. Disconnect control cable from bottom of junction box,
if the regulator has quick disconnect cable. Older units
that doesn't have a quick disconnect cable has a support
bar which is connected to the bottom of the junction box
and the top of the control box. Regulators with the
support bar on the junction box and control box, remove
the mounting hardware connecting the regulator to the
tank and raise the control with the internal of the
regulator.
3. Remove the series arrester. Release internal pressure
using pressure relief device and side of regulator.
4. Free cover by removing clamping ring or cover bolts.
5. Attach sling or hooks with spreader bar to lifting eyes
and raise the cover, with the attached core-and -coil
assembly, until the top of the coil is approximately one
inch under oil. As a safety precaution, blocking between
the cover and tank lip should be used until inspection of
the tap changer or other maintenance is complete. A
service cable assembly is available for operating an
untanked regulator from the mounted control cabinet (this
is only for regulator using a quick disconnect cable
setup), if connection cable is not long enough contact
customer service for availability.
6) If working conditions is unsafe due to the regulator
being to high in the air and working off a ladder, total
untank the regulator.
7) Recommend not leaving the regulator out of oil for
more then 4 hours.
Retanking the Regulator
Retank the regulator as follows:
1. Be sure position indicator shows present position of
the tap changer. If not, remove indicator cable in
junction box from position indicator shaft after loosening
the set screws. Rotate indicator shaft until proper
positions reached, then tighten set screws. Verify
coordination of position indicator with tap changer in the
neutral position
(control neutral light on).
2. Check gasket seat surfaces on cover and tank and
wipe clean. Wipe gasket and position on tank lip.
Loosen horizontal side channel blots to ensure proper
seating of regulator in tank and proper cover seal.
3. Raise cover assembly and attached components over
tank. Make certain of proper orientation.
4. Lower unit, rotation channels counter-clockwise into
tank guides.
5. Seat unit in tank. Tighten cover clamps or bolts.
Note: Tap cover with a rubber hammer around edge to
properly seal gasket while tightening cover band.
6. Check and retighten horizontal side channel bolts
through handhole, if required.
7. Properly reseal handhole cover, being careful not to
damage cover or insulation on the handhole cover bolt.
8. Connect control cable to connector at bottom of
junction box, if the quick disconnect application is used
on the regulator.
Maintenance and Inspection
The following is the recommended maintenance program
for a regulator that has been untanked:
1. Check all connections for tightness.
2. Check all contacts for wear (refer to page 4 ).
3. If possible avoid removing main core-and-coil
assembly from oil. If not removing from tank
fully use blocking between cover and tank lip for
safety.
If it is necessary to remove main core-and coil
assembly from oil, the following steps should be
followed.
4. Untanked
. If unit is out of oil more than four hours, it
must be rebaked for a minimum of 24 hours at
212 degrees F (100 degrees C). This is if a dry
air baking oven process is used. The maximum
number of times a unit should be rebaked is
twice over its life.
5. Baking:
A. Tap changer must not be subjected to tempera
tures above 150 degrees F (66degree C). Tap
changer must be removed if the unit is baked
at higher temperatures.
B. Within four hours after baking, the unit should
be retanked and filled with oil.
6. It is recommended that a vacuum be pulled on
the unit for at least one hour (2mm of vacuum
or better) after the unit is completely refilled
with oil. If vacuum processing is not available,
allow entire regulator assembly to soak in oil for
at least five days before energizing.
3
Reference Specifications for Voltage Regulator Maintenance
7. Check holding switch contacts & alignment
(Refer to alignment details pages 5 and 6)
8. Check motor capacitor terminal connections
should be tight. Capacitors on tap changer
inside tank must have both red leads on one
terminal and both blue leads on the other
terminal.
9. Neutral lamp switch alignment should be on
only in the neutral position and constantly on.
10. Check reactor brazing. Brazing should have
proper wetting with no cracks.
11. Check reactor tie-rods for tightness. If regulator
is noisy in the odd tap it could be due to
reactor. If so tighten both reactor tie rods.
Rods may be torque until ears on top and
lower core clamps starts to deflect inward.
12. Older regulators (before end of 1998), if the unit
is noisy in all taps it may be due to loose main
core-and-coil tie rods. Tie rods can be tighten
but care must be taken not to crush the winding
insulation.
13. Main core-and -coil packout- should not be
loose or crushed.
S225-50-15
14. Check tap changer stationary contact stud
torque:
Spring Drive = 110-115 in lb.
Direct Drive = 300 in lb.
Quik Drive = 180 in lb.
15. Position Indicator flex shafts should be in good
condition and adequately secured.
16. (Spring drive only) spring lock rings & chain
tension should checked.
Spring lock rings should not be over expanded
and seated in the groves.
Chain should have approxmately 1/8 of an inch
movement on each side of chain. Chain is not
to touch the cross member between the metal
plates. Chain is not to be tight. Tap changer is
to be in neutral to check chain tension.
17. Recommend oil test every 12-18 months for
units in Service.
A. Check oil dielectric strength (per ASTM D877)
New Unit
30KV min.
Service Aged 26 KV min.
B. Check oil moisture content (per ASTM D1533)
New Unit
25 ppm max.
Service Aged 30 ppm max.
C. Oil appearance should be clear.
21. Perform operational check.
22. When finished always check and make sure
regulator is truly in the neutral position.
Copper
Copper
Movable
Arcing
Contact
Arcing
Insert
Movable
Arcing
Contact
Stationary
Contact
New Contacts
Erosion
Arcing
Insert
Stationary
Contact
Erosion
Intermediate Stage
1/8 inch materal left
Movable Contact
Erosion has progressed to a point where
burning can occur on cooper
End of Contact Life Stage
Contact erosion is a function of many variables such as tap voltage, load current and power factor, reactor design and
tapped winding design. CPS employs both equalizer and conventional windings which will produce the typical erosion
pattern above.
Figure 1 Contact Inspection for Erosion
4
S225-50-15
Reference Specifications for Voltage Regulator Maintenance
.125 inch +/- .015 inch
.122 inch
Holding Switch
Assembly
Center Line
Fiber
Paddle
Insulators
Holding Switch
Motor
Motor Mounting
Bolt
Figure 2
Cam
Motor Mounting
Bolt
.122 inch
Spring Drive Tap Changer Motor and Holding Switch Assmenbly
Spring Drive Holding Switch
The spring drive tap changer holding switch is a three
bladed switch. The switch is operated by a cam located
on the output shaft of the motor.
For proper operation of the regulator and control the
holding switch must be properly aligned and adjusted.
The following steps are required for alignment and
adjustment of the holding switch anytime the switch is
replaced, moved for any reason such as motor replacement.
1. The center blade of the holding switch must be
aligned with the center line of the output shaft of the
motor.
A. Align the center blade by placing a pair of
needle noise pliers on the center blade, locate the needle
noise pliers back by the holding switch insulators
(See figure 2). Bend the blade up or down until alignment of the blade, not the fiber paddle is aligned with the
centerline of the motor output shaft.
and center blade paddle is .125 inch +/- .015 inch.
B. Use a .125 inch pin gauge to adjust the gap.
C. After setting the gap tighten the motor mounting
bolts.
3. To adjust the gaps between the center blade and
raise and lower blades of the holding switch.
A. Use a .122 inch pin gauge.
B. To adjust the gaps, locate a pair of needle noise
pliers back by the holding switch insulators on to the
blade to be adjusted. Bend the blade in or out away from
the center blade contact until both contact buttons just
touch the .122 inch pin gauge.
2. Adjust the gap between the holding switch paddle and
the inside surface of the cam.
A. Loosen the motor mounting bolts and adjust
the motor in or out until the spacing between the cam
5
Reference Specifications for Voltage Regulator Maintenance
S225-50-15
Holding Switch Mounting Screws
Holding Switch
Assembly
Pinon
Pinon
Holding Switch
Insulators
Motor
.122 inch
.122 inch
Fiber Paddle
.090 inch
+ .015 / - .000 inch
Cam
Shaft
Geneva Gear
Figure 3
Center Line
Direct Drive Tap Changer Motor and Holding Switch Assembly
Direct Drive Tap Changer Holding Switch
and center blade paddle is .090 inch + .015 inch / - .000.
The direct drive tap changer holding switch is a three
bladed switch. The switch is operated by a cam located
on the geneva gear output shaft.
For proper operation of the regulator and control the
holding switch must be properly aligned and adjusted.
The following steps are required for alignment and
adjustment of the holding switch anytime the switch is
replaced or moved.
B. Use a .090 inch pin gauge to adjust the gap.
C. After setting the gap tighten the holding switch
mounting screws.
1. The center blade of the holding switch must be
aligned with the center line of the output shaft which the
cam is located.
A. Align the center blade by placing a pair of
needle noise pliers on the center blade, locate the needle
noise pliers back by the holding switch insulators
( See figure 3). Bend the blade right or left until alignment of the blade, not the fiber paddle is aligned with the
center line of the camshaft.
2. Adjust the gap between the holding switch paddle and
the inside surface of the cam.
A. Loosen the holding switch mounting screws
and adjust the holding switch in or out until the spacing
between the cam
6
3. To adjust the gaps between the center blade and
raise and lower blades of the holding switch.
A. Use a .122 inch pin gauge.
B. To adjust the gaps, locate a pair of needle noise
pliers back by the holding switch insulators on to the
blade to be adjusted. Bend the blade in or out away from
the center blade contact until both contact buttons just
touch the .122 inch pin gauge.
S225-50-15
Reference Specifications for Voltage Regulator Maintenance
Recommended Field and Shop Test for
Service Aged Regulators
A. Operational Test
1. With internal voltage applied to the regulator manually
operate the control a few steps rise until you see an out
of band indication on the control display.
2. Place the control Function switch to Auto. The
regulator should tap until the out of band indicator is off.
3. Repeat steps 1 and 2, but in the lower direction.
4. Manually operate the regulator back to neutral and
turn the Control Function Auto/Remote Manual switch to
off.
5. Turn off the control power switch.
F. Oil Sample
1.
2.
3.
4.
5.
Pull oil sample and test dielectrics and moisture.
Dielectric strenght test per ASTM D877 (26kv min).
Moisture test per ASTM D1533 (30ppm max).
Oil power factor test per ASTM D924 (1.0% max).
Oil appearance - should be clear.
B. Low Voltage Ratio Test or Ratio Test using a
Ratio Bridge.
C.
Potential Transformer Ratio Test
1. Determine the ratio of the potential transformer from
the nameplate.
2. Apply 120 volts to the primary side of the potential
transformer.
3. Determine the correct secondary voltage by the
following:
Input Voltage (120 Vac)
PT Ratio
D. Megger Test
E. Hipot Test
1. Short by connecting all three bushing terminals
together.
2. Connect Hipot tester leads to the bushing and tank.
3. Place the tap changer on the 16 lower position.
4. Hipot regulator at 60 percent of rated Bil level.
Bil level
95
150
200
K Volts
34.5
50
70
5. Hipot for 60 seconds.
7
Reference Specifications for Voltage Regulator Maintenance
S225-50-15
ELECTRICAL CLEARANCES IN OIL
IEEE C57.12.00-2000
This section establishes the minimum required electrical
clearances for stationary, non-arcing energized parts in oil.
These oil clearances generally apply for conductors and
componentry installed inside pad-mounted transformer tanks
at least one inch below the cold (-20C) oil level. The clearances specified in this section were developed to withstand
the electrical tests specified by C57.12.00-2000, C57.12.10-1997,
C57.12.22-1989, and C57.12.26-1992. All clearances shown are
minimums for the product. Normal practice is to allow at least
0.25” of additional clearance for tolerance. More than 0.25”
tolerance may be required in some cases. Components with
moveable or arcing parts, such as fuses and loadbreak
switches, may require additional clearance. High-current
carrying parts may require seperation greater than the electrical minimum to allow for cooling. The following documents
should be referenced when determining electrical clearances in
air.
IEEE C57.12.10-1997
IEEE C57.12.22-1989
IEEE C57.12.26-1992
Standard General Requirements for
Liquid-Immersed Distribution, Power,
and Regulating Transformers
230kV and Below 833/958 – 8333/10
417 kVA Single Phase, and 750/862 –
60 000/80 000/100 000 kVA ThreePhase Without Load Tap Changing –
Saftey Requirements
Pad-Mounted, Compartmental-Type,
Self-Cooled, Three-Phase Distribution
Transformers, 2500 kVA and Smaller:
High Voltage 34500GY/19920V and
Below; Low Voltage 480V and Below
Pad-Mounted, Compartmental-Type,
Self-Cooled, Three-Phase Distribution
Transformers for use with Separable
Insulated High-Voltage Connectors
(34500GY/19920V and Below; 2500
kVA and Smaller)
2300 Badger Drive
Waukesha, WI 53188-5951
© 2001 Cooper Industries, Inc.
8
http://www.cooperpower.com