Eaton COOPER POWER SERIES Manual

Substation transformer installation, operation, and maintenance
instructions and parts replacement information
COOPER POWER
SERIES
Effective June 2016
Supersedes S210-15-10 February 2013
Substation
Transformers
MN202002EN

DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITY
The information, recommendations, descriptions and safety notations in this document are based on Eaton Corporation’s
(“Eaton”) experience and judgment and may not cover all contingencies. If further information is required, an Eaton sales
office should be consulted. Sale of the product shown in this literature is subject to the terms and conditions outlined in
appropriate Eaton selling policies or other contractual agreement between Eaton and the purchaser.
THERE ARE NO UNDERSTANDINGS, AGREEMENTS, WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING WARRANTIES
OF FITNESS FOR A PARTICULAR PURPOSE OR MERCHANTABILITY, OTHER THAN THOSE SPECIFICALLY SET OUT IN ANY
EXISTING CONTRACT BETWEEN THE PARTIES. ANY SUCH CONTRACT STATES THE ENTIRE OBLIGATION OF EATON. THE
CONTENTS OF THIS DOCUMENT SHALL NOT BECOME PART OF OR MODIFY ANY CONTRACT BETWEEN THE PARTIES.
In no event will Eaton be responsible to the purchaser or user in contract, in tort (including negligence), strict liability or other-
wise for any special, indirect, incidental or consequential damage or loss whatsoever, including but not limited to damage or
loss of use of equipment, plant or power system, cost of capital, loss of power, additional expenses in the use of existing
power facilities, or claims against the purchaser or user by its customers resulting from the use of the information, recom-
mendations and descriptions contained herein. The information contained in this manual is subject to change without notice.
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Contents
DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITY ................................... II
SAFETY FOR LIFE .........................................................................IV
SAFETY INFORMATION ....................................................................IV
Safety instructions.............................................................................. iv
PRODUCT INFORMATION................................................................... 1
Introduction ....................................................................................1
Acceptance and initial inspection ...................................................................1
Handling.......................................................................................1
Storage .......................................................................................1
Quality standards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
INSTALLATION............................................................................ 2
Installation location ..............................................................................2
Connections....................................................................................2
Final inspection .................................................................................2
ACCESSORIES ............................................................................ 4
Liquid level gauge ...............................................................................4
Liquid temperature gauge .........................................................................4
Pressure-vacuum gauge ..........................................................................5
Pressure relief device ............................................................................5
Winding temperature gauge .......................................................................6
Transformer cooling fans ..........................................................................6
High voltage bushings ............................................................................7
Low voltage bushings ............................................................................7
De-energized tap-changer .........................................................................8
Insulating liquid .................................................................................8
Vacuum fault interrupter (VFI) ......................................................................9
MAINTENANCE ...........................................................................11
Periodic inspection .............................................................................11
Removing and replacing bushings..................................................................11
Removing and replacing draw lead type bushings .....................................................11
Removing and replacing fixed stud or spade type bushings..............................................12
Cover removal .................................................................................13
Insulating liquid maintenance .....................................................................14
APPLICABLE STANDARDS ................................................................. 14
R-TEMP FLUID-FILLED TRANSFORMERS ..................................................... 14
Dielectric strength ..............................................................................14
PEAK™ AND ENVIROTEMP™ FR3™ FLUID-FILLED TRANSFORMERS ............................. 15
Spare parts and service..........................................................................15
PREVENTATIVE MAINTENANCE INSTRUCTIONS .............................................. 16
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The instructions in this manual are not intended as a
substitute for proper training or adequate experience in the
safe operation of the equipment described. Only competent
technicians who are familiar with this equipment should
install, operate, and service it.
A competent technician has these qualifications:
• Is thoroughly familiar with these instructions.
• Is trained in industry-accepted high and low-voltage safe
operating practices and procedures.
• Is trained and authorized to energize, de-energize, clear,
and ground power distribution equipment.
• Is trained in the care and use of protective equipment
such as arc flash clothing, safety glasses, face shield, hard
hat, rubber gloves, clampstick, hotstick, etc.
Following is important safety information. For safe installa-
tion and operation of this equipment, be sure to read and
understand all cautions and warnings.
Safety instructions
Following are general caution and warning statements that
apply to this equipment. Additional statements, related to
specific tasks and procedures, are located throughout the
manual.
Safety for life
!
SAFETY
FOR LIFE
!
SAFETY
FOR LIFE
Eaton meets or exceeds all applicable industry standards relating to product safety in its Cooper Power™ series products.
We actively promote safe practices in the use and maintenance of our products through our service literature, instructional
training programs, and the continuous efforts of all Eaton employees involved in product design, manufacture, marketing,
and service.
We strongly urge that you always follow all locally approved safety procedures and safety instructions when working around
high voltage lines and equipment, and support our “Safety For Life” mission.
Safety information
DANGER
Hazardous voltage. Contact with hazardous voltage will
cause death or severe personal injury. Follow all locally
approved safety procedures when working around high-
and low-voltage lines and equipment. G103.3
WARNING
Before installing, operating, maintaining, or testing this
equipment, carefully read and understand the contents
of this manual. Improper operation, handling or
maintenance can result in death, severe personal injury,
and equipment damage. G101.0
WARNING
This equipment is not intended to protect human
life. Follow all locally approved procedures and safety
practices when installing or operating this equipment.
Failure to comply can result in death, severe personal
injury and equipment damage. G102.1
WARNING
Power distribution and transmission equipment must
be properly selected for the intended application. It
must be installed and serviced by competent personnel
who have been trained and understand proper safety
procedures.These instructions are written for such
personnel and are not a substitute for adequate training
and experience in safety procedures. Failure to properly
select, install or maintain power distribution and
transmission equipment can result in death, severe
personal injury, and equipment damage. G122.3
This manual may contain four types of hazard statements:
DANGER
Indicates an imminently hazardous situation which, if
not avoided, will result in death or serious injury.
WARNING
Indicates a potentially hazardous situation which, if not
avoided, could result in death or serious injury.
CAUTION
Indicates a potentially hazardous situation which, if not
avoided, may result in minor or moderate injury.
CAUTION
Indicates a potentially hazardous situation which, if not
avoided, may result in equipment damage only.
Hazard Statement Definitions
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Product information
CAUTION
Do not Exceed Transformer Ratings. Transformers
should be operated only at the ratings specified on the
transformer nameplate. Prolonged overload operation
will measurably shorten the projected service life of a
mineral oil-filled transformer. Eaton’s Cooper Power™
series PEAK™ transformers may help to extend
insulation life and can be operated at higher capacities
than traditional units while still exceeding ANSI®
standard insulation life.
Introduction
This manual has been prepared to assist competent techni-
cians in the installation, operation and service of primary or
secondary unit- or open-type substation trans-formers.
Substation transformers are designed for installation on
three-phase systems. All units are constructed for in-door
or outdoor mounting on a concrete pad with high and low
voltage cables entering operating compartments through
enclosed sidewall mounted bushings (unit-type transform-
ers) or through cover or sidewall mounted bushings (open-
type transformers).
Although every effort has been made to anticipate normal
installation, operation and servicing problems, these instruc-
tions do not cover all possible variations in equipment or
application conditions. All possible installation, operation or
service contingencies are not discussed. If additional infor-
mation is required, contact a factory representative.
It is important that personnel using these instructions
be fully acquainted with industry accepted high and low
voltage safe operating practices and procedures. These
instructions are not intended as a substitute for proper
training or adequate experience in the safe operation of the
equipment described.
Read this manual first
Read and understand the contents of this manual and follow
all locally approved procedures and safety practices before
installing or operating this equipment.
Additional information
These instructions cannot cover all details or variations in
the equipment, procedures, or process described, nor to
provide directions for meeting every possible contingency
during installation, operation, or maintenance. For additional
information, contact your Eaton representative.
Acceptance and initial inspection
It is important that a thorough inspection of the transformer
be made before it is unloaded from the carrier.
1. Ensure that all parts listed on the bill of lading are
present.
2. Before unloading the transformer, make an inspection to
detect any signs of damage or mishandling. Locate any
accessory parts that may have been shipped separately.
3. If any damage is detected or shortages are noticed,
write a brief description on the freight bill. Normally, the
transformer is shipped FOB point of manufacture, and
it is the customer's responsibility to file a claim against
the carrier. If the transformer was shipped FOB destina-
tion, notify your factory representative. He or she will,
with the inspector's report, take the necessary steps to
file a claim against the carrier.
Handling
For unloading, lifting hooks are provided near the top of the
transformer tank. Cable pull angles should not be over 30°
from vertical. Otherwise, spreaders should be used to hold
the lifting cables apart to avoid any bending of the structure
or lifting hooks.
WARNING
Do not attempt to lift the transformer by placing a con-
tinuous loop of cable or chain around the unit or lifting
lugs. Improper handling can result in death, severe per-
sonal injury and equipment damage.
If the transformer cannot be lifted by crane, it may be
skidded or moved with rollers. When jacking a transformer
to insert rollers underneath it, insure that at least two jacks
are used and that two adjacent corners are raised simulta-
neously and evenly to avoid warping the base. Jacks may be
placed only at the corners of the transformer base.
Do not place jacks under cooler assemblies, valves, or sheet
metal parts. When using rollers, use as many as necessary
to distribute the weight uniformly. To pull, attach pulling eyes
to the holes in the base at either end of the transformer.
Do not attach pulling lines to moldings or other sheet metal
parts of the transformer.
Storage
Whenever possible, the transformer should be stored at its
permanent location.
The insulating liquid should be at its proper level and the
gas space pressurized with dry nitrogen to approximately
two psig. Then it should be tightly sealed so that no
moisture or air can enter the tank. Periodic inspection
should determine that the pressure gauge does not remain
at zero, and proper liquid level is maintained at all times.
The transformer should not be stored in the presence of
corrosive gases (e.g., chlorine). Exterior surfaces of the trans-
former should be maintained against rust and corrosion.
Before placing a transformer into service after an ex-tended
storage time, check fans, alarm and control circuits, and the
dielectric strength of the insulating liquid.
Quality standards
ISO 9001 certified quality management system
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Installation
Installation location
The transformer should be located on a concrete pad of
sufficient strength to support the weight of the unit. The
pad must be level. The location of the transformer, whether
indoor or outdoor, should provide for adequate accessibility,
ventilation and ease of inspection. The transformer should
be at least 24 inches from any obstruction. These are
the recommendations of the manufacturer for operation
purposes; see your local codes for additional guidelines.
Location in areas of corrosive chemicals should be avoided.
These substation transformers are built to operate at
altitudes up to 3300 feet at 30°C average and 40°C
maximum ambient, unless otherwise specified. Before
operating a standard transformer at higher altitudes, contact
your factory representative.
Adequate ventilation must be provided. For indoor
installations, room air inlets should be located at floor level;
the air outlets should be located as high as the room will
permit. The number and size of the air inlets depends upon
the rating of the transformer. In general, about 20 square
feet each of inlet and outlet area should be provided for
each 1000 kVA of transformer capacity. If the ventilation
system is adjustable, it should be locked permanently open
to avoid overheating of the transformer in case of operator
error.
Connections
Connections must be made without placing undue stress
on the bushing terminals. Conductors should be securely
fastened in place and supported properly, with allowance
for expansion and contraction. Make sure that the tap
connection is proper for the required voltage. Changes in
tap connections must be done ONLY with the transformer
high voltage and low voltage circuits completely
"DE-ENERGIZED". Safely verify that there is no voltage
present at the terminals.
WARNING
Do not change connections on a transformer that is
energized. Ground all circuits before making any trans-
former connection. Failure to observe precautions when
making connections can result in exposure to high volt-
ages, which can cause death, severe personal injury or
damage to the equipment.
WARNING
Do not make any connections, except as authorized by
the nameplate or schematic. Improper connections
can result in severe personal injury and damage to the
equipment.
Transformers equipped with an internal terminal board are
normally shipped with the higher voltage connected, unless
otherwise specified by the customer.
A secure and effective low resistance ground is essential
for protection. The transformer must be grounded perma-
nently by connecting a heavy ground cable to the ground
pad located at the bottom of the tank. If the transformer is
designed for operation in a solidly grounded neutral system,
the neutral connection should be solidly and permanently
grounded with minimum resistance.
WARNING
Improper grounding may result in personal injury or
damage to the equipment.
Lightning arresters are recommended for every trans-former
installation. Arresters of proper rating should be located as
close as possible to the transformer terminations.
When alarm contacts or controls are supplied with the
transformer accessories, a connection box may be provided
to facilitate termination of the customer's cable or conduit.
Final inspection
The final inspection can be done in three major steps:
Electrical, Internal and External.
WARNING
Do not tamper with interlocks, alarm or control circuits.
Doing so can produce unsafe conditions for operators or
result in damage to the equipment.
Electrical inspection should determine that:
1. All external connections have been made properly
(phasing of connections to terminal bushings, etc.).
2. All connections are tight and secure.
3. All accessory contact circuits are operational.
4. Current transformer circuits, if supplied, have secondar-
ies either shorted or connected through their load.
5. Tap changer is operative and properly positioned.
6. The correct transformer ratio exists for units furnished
with internal terminal board.
7. There is no grounding of windings that are not
intended to be grounded. A 1000-volt megger test is
recommended.
8. There is continuity in all windings.
9. The dielectric strength of the insulating liquid is
30 kV minimum when new. (Refer to section for
"Testing Insulating Liquid" in this manual.)
10. The neutral and ground connections have been properly
made.
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If an internal inspection is required, assure that:
1. There is no evidence of moisture.
2. All available bolted connections are tight.
3. There has been no shifting of any parts or any other
damage.
The external inspection should determine that:
1. All scratches have been painted.
2. The bushings are clean.
3. The accessories are operative.
4. There are no tools, or other objects, left on top of the
transformer or inside any enclosure.
5. The liquid level is correct.
6. The transformer holds positive pressure.
7. The manhole covers are tightly bolted.
8. All protective covers are closed and bolted tight.
9. The mechanical pressure relief device is reset.
CAUTION
Whenever it is necessary to open a liquid-filled trans-
former, insure that the liquid temperature is higher
than the outside air temperature. Otherwise, internal
moisture condensation may occur, which could lead to
failure of the transformer.
CAUTION
Before breaking the seal of any handhole, manhole or
bushing hole, bleed internal pressure to zero. Seals
should not be broken in the presence of fog, rain or
snow, or if there is any evidence of condensation on the
transformer tank. If even a very slight amount of such
moisture enters the transformer tank, it can decrease
the dielectric strength of the cooling liquid to danger-
ously low levels, which can result in damage to the
equipment.
CAUTION
Only authorized personnel should be permitted on top
of the transformer and every precaution should be taken
to avoid dropping objects into the transformer. Workers
should not have anything in their pockets (such as pens,
pencils, coins, etc.) and their clothing should not have
loose metal buttons, badges, buckles, etc. Wristwatches
should also be removed. When dropped into the
transformer tank, such objects can cause equipment
malfunction and damage.
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Accessories
Liquid level gauge
A liquid level indicator is provided to aid in the systematic
inspection of the transformer under load. It consists of
a float-arm inside the tank, an indicating pointer and a
magnetic coupling between the two across a liquid-tight
separation. Under normal operating conditions, the pointer
should be between the lo/min and hi/max level markings.
The gauge may be furnished with SPDT (Single Pole Double
Throw) alarm contacts to give a remote annunciation of
low liquid level. For contact wiring and terminal points,
see the accessory connection diagram furnished with the
transformer.
Liquid temperature gauge
The temperature gauge is furnished to indicate the top
liquid temperature in the tank in degrees Centigrade. The
temperature-sensitive element is mounted in a leak-proof
well, permitting removal of the thermometer without lower-
ing the oil level. The device is furnished with an additional
red pointer to show the highest temperature attained since
the last reset. To reset the maximum indicator, turn the knob
in the center of the dial.
The thermometer can be furnished with two SPDT contacts
for a high temperature alarm, for energizing a fan circuit or
for a low temperature alarm. The trip settings are indicated
by the red tick marks on the edges of the dial. For additional
wiring and contact settings, refer to the schematic furnished
with the transformer.
Figure 1. Liquid level gauge.
Figure 2. Liquid temperature gauge.
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Pressure-vacuum gauge
The pressure-vacuum gauge indicates whether the gas
space in the tank is under positive or negative pressure.
The pressure will vary depending on the transformer
temperature. If the transformer is de-energized or operating
under light load in low ambients, the pressure may be
negative.
ote:N If the indicator reads zero and does not change
under any load condition, the transformer should be
checked for a possible leak in the seal.
If sufficient air has been absorbed by the liquid during
shipment or storage, the transformer may operate
indefinitely in the vacuum range, depending upon the
loading conditions. This, in itself, is not cause for concern,
provided the pressure vacuum gauge does not remain
on zero for any length of time an indication of a leak. The
transformer can safely operate in pressures ranging from -2
to +6 psig.
The unit may be equipped with pressure vacuum switches
with two SPDT contacts for remote alarm on positive and
negative pressure. For wiring and contact ratings, refer to
the schematic furnished with the transformer.
When required, the pressure gauge is furnished with a
pressure regulator that will automatically regulate the tank
pressure between 7.0 psig positive and 3.0 psig negative.
The pressure regulator is fitted with a valve and fitting to
take gas samples.
Pressure relief device
All substation transformers are furnished with a mechanical
pressure relief valve (PRV) or pressure relief device (PRD).
The cover-mounted PRD consists of a self-resetting, spring-
loaded diaphragm and a mechanical operation indicator.
Should the tank pressure increase above that for which the
device is set, the gas pressure will lift the diaphragm and
let the gas escape quickly. Immediately after the pressure
returns to normal, the diaphragm will reset and reseal the
transformer. A mechanical indicator will protrude vertically.
This must be reset manually to indicate subsequent
operations.
Contacts are optional. For wiring information, refer to the
schematic furnished with the transformer.
Figure 4. Pressure relief device.
Figure 3. Pressure-vacuum gauge.
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Winding temperature gauge
Transformers may be furnished with a winding temperature
gauge as optional equipment. A temperature sensitive
stem is mounted in a leakproof well, permitting removal of
both the instrument and stem without lowering the liquid
level. The well is heated by both the surrounding liquid
and a heater element which is energized from a current
transformer mounted inside the tank to simulate the hot
spot winding temperature gradient. The combination of the
two temperatures is indicated on the gauge. An additional
red pointer is furnished to show the highest temperature
attained since the last reset. The maximum indicator is
resettable by means of a pushbutton through the bottom of
the dial bezel.
The gauge has three separate SPDT switches for fan control
and alarm circuits. For wiring the contact settings, refer to
the schematic furnished with the transformer.
The equipment is calibrated to indicate the hottest spot
of the transformer windings. All contacts are factory set
to operate at the temperatures shown in the connection
diagram.
If readjustment of the contacts is desired, consult the
factory for detailed instruction.
Transformer cooling fans
In order to increase the transformer load without
overheating the windings, a set of fans can be furnished as
an optional item. Fan control consists of a contact on either
the liquid temperature gauge or the winding temperature
gauge (when furnished), and "Manual-Auto" control switch.
For continuous run, the switch is turned to the "Manual"
position. In the "Auto" position, the fans are controlled by
the contacts on the temperature gauge. For contact and
temperature settings, refer to the schematic furnished with
the transformer.
WARNING
Fan guards are furnished and installed for your
protection. Do not remove fan guards or probe into
the fan with long objects. Doing so can result in severe
personal injury and equipment damage.
Refer to wiring schematic for control equipment supplied.
Figure 5. Winding temperature gauge. Figure 6. Transformer cooling fan.
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High voltage bushings
High voltage leads for ratings 2.4 kV and up are normally
brought through the tank end wall using a cycloaliphatic
epoxy or porcelain bushing. To prevent excessive mechanical
loading of the bushing, only flexible connections should be
made to the bushing terminal. The bushing should never
be used as a structural member to support other current-
carrying parts.
Care must be taken in handling the bushing to avoid
cracking the porcelain or damaging its surface.
Should it become necessary to replace a bushing or its
gasket, proceed as follows:
1. Vent the tank to the atmosphere until pressure is zero.
2. Lower the liquid level to a point below the bushing
level.
3. Remove the nuts and washers used to clamp the
flange of the bushing.
4. Pull the bushing outward as far as necessary to replace
the gasket and/or to unfasten the cable connection at
bushing inner end.
Only in rare circumstances will there be insufficient slack
in the cable leads to facilitate bushing replacement through
the wall. The alternative means of gaining access to the
connections is through the manhole.
When reinstalling the bushing, install a new gasket in the
gasket recess on the underside of the flange to insure that
the gasket is properly seated in the groove. A flat washer
and lock washer should be placed between the mounting
nut and the flange. After the nuts are finger tight, each one
should be tightened to a torque of 60±5 inch pounds. After
completion, pressure test the transformer.
When condenser-type bushings are used, supplementary
leaflets forming a part of the complete instruction book will
be provided.
Low voltage bushings
Low voltage leads for ratings in the 1.2 kV Class are
normally brought through the tank wall using an indoor
bushing. This is a cast resin, cycloaliphatic epoxy or
porcelain bushing.
The low voltage bushing should not be used as a structural
member. As a rule, only flexible connections should be
made to any bushing. Avoid rigid connections between
the bushing and other bus supports to eliminate thermal
expansion forces to the bushing.
If a bushing is damaged and leaking transformer coolant,
contact your factory representative for proper repair
procedures.
Figure 7. High voltage bushing.
Figure 8. Low voltage bushings.
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De-energized tap-changer
WARNING
Do not operate the tap-changer while the transformer is
energized. Doing so can result in severe personal injury
and equipment damage.
The tap-changer provides a means of changing the voltage
ratio of a de-energized transformer without breaking the
transformer seal. It is operated by means of a rotatable
handle located on the side of the transformer. The tap-
changer is normally provided with five or seven positions,
as indicated on the tap-changer dial plate and transformer
instruction nameplate.
Insulating liquid
The insulating liquid in substation transformers is
either conventional transformer oil, R-Temp™ fluid or
Envirotemp™ FR3™ fluid. When makeup liquid is required,
use only approved fluid of the same type that is in the
transformer. It is important to check the proper liquid level
in the transformer at all times by periodically observing the
liquid level gauge. In addition, the dielectric strength of the
insulating liquid must be maintained at a high value.
It is recommended that a sample be taken of the liquid and
tested within one week after energization, and annually
thereafter.
Figure 9. De-energized tap-changer.
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Vacuum fault interrupter (VFI)
Eaton’s Cooper Power series VFI transformers utilize
vacuum interrupters to provide fault current interruption and
load make/break switching capabilities. The VFI transformer
uses the same technology used in Eaton’s Cooper Power
series VFI pad-mounted switchgear.
VFI transformers can be specified for either transformer
protection or loop protection. A VFI transformer with
transformer protection protects the transformer and
provides proper coordination with upstream protective
devices. A VFI transformer with loop protection protects
the loop or downstream section of a feeder. Consequently,
when a fault occurs downstream, the VFI breaker trips and
isolates the fault, leaving the transformer load uninterrupted.
The VFI interrupter mechanism in a VFI transformer has a
hotstick-operable handle located on the faceplate of the
transformer, with the operating mechanisms configured
for ganged three-phase operation (see Figure 24). The VFI
interrupter mechanism is opened by pulling the operation
handle down to the open position. The VFI interrupter
mechanism is closed by briskly pushing the handle up,
into the closed position. If the VFI interrupter mechanism
has tripped as the result of a fault or overload condition,
the mechanism must be reset before it can be closed. To
reset the mechanism, firmly pull the operation handle down
toward the ground until the latch resets. After the latch has
been successfully re-set, the VFI interrupter mechanism can
be closed normally.
Figure 10. VFI operating handle.
IMPORTANT
For 75°C AWR transformers, applications with
maximum ambient temperatures exceeding 30°C or
loading in excess of nameplate rating, contact your
Eaton representative.
WARNING
Hazardous voltage. Can cause severe injury, death, or
damage to equipment.
• Do not operate loadbreak equipment if a fault
condition is suspected. Doing so can cause an
explosion or fire.
• Use a hotstick to operate transformer loadbreak
equipment.
• After operating transformer loadbreak equipment,
check that voltages at transformer terminals are
the expected values. Checking voltages verifies that
loadbreak equipment operated properly and that
electrical circuit conditions are as expected.
• Before servicing transformer secondary connected
equipment, verify that all transformer secondary
terminals have zero voltage and ground the
transformer secondary terminals following industry
accepted safe grounding practices. Grounding
secondary terminals protects against situations such
as a standby generator energizing transformer from
the secondary circuit.
• Before servicing transformer, ALWAYS de-energize
the transformer from a remote upstream source and
then proceed to ground all primary and secondary
transformer terminals following industry accepted
safe grounding practices. Grounding secondary
terminals protects against situations such as a
standby generator energizing transformer from the
secondary circuit.
• Follow industry accepted safety practices. Utilize
protective clothing and equipment when working
with loadbreak equipment.
WARNING
Three-phase pad-mounted transformers use
conventional transformer oil, R-Temp fluid, or
Envirotemp™ FR3™ fluid for an insulating liquid. When
the insulating liquid temperature is less than -20°C
(-4°F) for conventional transformer oil, less than 0°C
(32°F) for R-Temp fluid or less than -10°C (14°F) for
Envirotemp™ FR3™ fluid, viscosity is reduced, which
may reduce make and break capabilities of loadbreak
devices. Below these temperatures, under-oil loadbreak
accessories should not be used to make or break a
load. Instead, de-energize transformer from a remote
upstream source before operating under-oil loadbreak
devices.
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Current-sensing transformers (CTs) located inside the
VFI transformer provide line current information to the
electronic control. When line current exceeds the minimum
trip setting, the control initiates a signal which causes the
VFI interrupter mechanism to trip and then interrupt the
circuit. All three phases will open when the VFI interrupter
mechanism is tripped, regardless of whether the trip was
single-phase or three-phase initiated.
Refer to Service Information S285-75-1, Tri-Phase, TPG,
and TPG with SCADA Electronic Control Installation and
Operation Instructions for electronic control operation
instructions.
Standard electrical ratings for Eaton VFI transformers are as
follows:
Continuous Current (max) .....................600 A
Interrupting Current (sym./asym.)...........12 kA/20 kA
Momentary Current 10 cycles (asym.) ............20 kA
1-Second Withstand Current (sym.). .............12 kA
Making Current (sym.) ........................12 kA
For further information on Eaton VFI transformers including
additional ratings, contact your Eaton representative.
10 SubStation tranSformer inStallation and partS replacement information MN202002EN JUNE 2016

Maintenance
Periodic inspection
1. External: Periodically check the condition of the paint
and finish, especially when the transformer is exposed
to inclement atmospheric conditions. If weathering
takes place, clean the tank thoroughly, wipe off any
insulating liquid that might have been spilled on the
surface and repaint with a factory approved paint.
Occasionally, inspect and tighten all bolted joints and
check for leaks.
2. Regularly inspect all gauges. The liquid level must
remain normal, considering the temperature effect.
Refill when samples have been taken. Prolonged
periods of zero pressure could indicate a gas leak and
should be checked out. The liquid temperature should
not rise higher than the design value on the nameplate,
plus ambient temperature.
3. Liquid samples should be taken periodically and
analyzed as indicated under "Sampling". It is recom-
mended that you keep a log of the test values to
determine when reconditioning or replenishing service
is required.
Removing and replacing bushings
Bushing construction falls into two general categories:
"draw lead" type as represented by Figure 12 and bottom
connected types with a fixed center stud or internal spade
as represented by Figure 13.
The method for removing bushings will differ depending
upon the type of construction. The two methods are dealt
with separately in the written material that follows.
Before any work commences, standard safety precautions
must be observed.
WARNING
Before working with bushings, make sure that the
transformer is de-energized and that all circuits to
and from the transformer are grounded in order to
discharge any stored energy and prevent accidental
re-energization. Failure to do so may result in death,
severe personal injury and equipment damage.
Additional precautions include the following:
• Lock in the “open” position disconnect switches in the
supply lines to and from the transformer.
• If the transformer is under vacuum or pressure, bring the
tank to ambient pressure.
• If the bushing to be removed is below the liquid level,
lower the level sufficiently to prevent fluid loss.
• To protect from the atmosphere and contaminants, store
in clean, dry, sealed containers any removed liquid that
will be returned to the transformer.
Removing and replacing draw lead type bushings
Removing
1. Unscrew and remove the top terminal cap, exposing
the threaded stud end of the draw lead cable. In some
cases, the threaded stud will be held by a pin that must
also be removed.
2. Fasten a pull wire, cord or rod to the stud in order to
guide the lead through the bushing’s bore and prevent
it from falling into the opening when the bushing is
removed. (In some cases, the lead will be of sufficient
thickness to be self-supporting; if so, this part of the
procedure can be omitted).
3. Remove the bushing mounting clamp nuts at the tank
to release the mounting clamp plate and free the
bushing for removal.
4. Remove the bushing, guiding the draw lead conductor
and terminal stud through the base of the bushing.
Figure 11. Draw lead type bushing.
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Replacing
Replacement draw lead type bushings can be installed by
following the removal procedure in reverse order. Clamp
bolts should be tightened as specified in Table 1.
The gasket under the bushing mounting flange and the
top gasket should be new or in good condition to ensure a
positive seal. The gasket mating surfaces must be clean and
smooth.
The threaded stud is keyed to the inside of the bushing to
prevent rotation while the terminal cap is being tightened. It
is important to have the threaded stud correctly seated. This
can be accomplished by pulling the stud up and turning it
until it is aligned and seated.
Removing and replacing fixed stud or spade type
bushings
Removing
1. Remove inspection cover (manhole) nearest to bushing,
only after all precautions outlined under "Removing and
Replacing Bushings" have been taken.
2. To remove the inspection cover:
A. Thoroughly clean the cover. Remove all dirt, grease
and moisture.
B. Release and remove cover bolts.
C. Remove the cover. Lift vertically to prevent damage
to bolt or cover gaskets.
3. Unbolt the connections–usually flexible straps–from the
bottom end of the bushing stud.
4. Remove the bushing mounting clamp nuts at the tank
to release the mounting clamp plate and free the
bushing for removal.
5. Remove the bushing.
Replacing
Replacement bushings can be installed by following the
removal procedure in reverse order. Clamp bolts should be
tightened as specified in Table 1.
The gasket under the bushing mounting flange should be
new or in good condition, and the gasket mating surfaces
must be clean and smooth.
After installing and connecting the new bushing, replace
the inspection opening cover, making certain the gasket is
in good condition and the gasket mating surfaces are clean
and smooth.
Return to the transformer any liquid removed and check for
the correct level.
A brief pressure test of the transformer at 5 psig to confirm
the integrity of the seals around all openings above the
liquid level is recommended. A solution of soap and water
will give indication of a leak by the presence of bubbles.
Bushing Clamps
4-hole Aluminum Cast Bushing Clamps 70-80 in.-lbs.
Molded Tri-Clamp Bushing 40-60 in.-lbs.
All other 3- & 4-hole Bushing Clamps 40-60 in.-lbs.
2-hole Bushing Clamps 55-65 in.-lbs.
TABLE 1 Torque Values
Internal Spade Bushings
1/2" Steel (Grade 8) 50 ft.-lbs.
3/8" Steel (Grade 8) 50 ft.-lbs.
Internal Stud Bushings
3/8"-16 Brass Nuts 16 ft.-lbs.
5/8"-11 Aluminum Nuts 60 ft.-lbs.
5/8"-11 Brass Nuts 75 ft.-lbs.
1"-14 Brass Nuts 121 ft.-lbs.
Bushing Lead Block, ½” Steel Hardware 110 ft.-lbs.
Figure 12. Fixed stud and spade type bushings.
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Cover removal
(For Envirotemp™ FR3™ fluid-filled units, see “Insulating
Liquid Maintenance” Section before continuing.)
Transformers that have been system connected should be
de-energized, grounded, and disconnected before being
opened for inspection.
Substation transformers may have either bolt-on or weld-
in-place main tank covers. Access to the interior of a trans-
former with a bolt-on main tank cover without handholes
requires removal of the entire cover. Access to the interior
of the welded-in-place main tank cover design is typically
through manhole or handholes.
WARNING
Before the tank cover, manhole cover or handhole cover
is removed, the transformer tank must be vented to zero
pressure by activating the pressure relief valve. Failure
to do so may result in severe personal injury, death or
property damage.
CAUTION
If the main tank cover, manhole cover, handhole cover
or access cover must be removed for internal inspection
or service of the transformer, precautions must be taken
to prevent dirt or moisture from entering the opened
unit. Contamination of the insulating fluid will prevent
the transformer from operating properly and may cause
serious damage to the transformer.
WARNING
Transformers must never be opened or serviced
while system is connected, ungrounded or energized.
Tampering with the covers or cover seals of a
transformer that has not been de-energized, grounded
and disconnected may result in severe personal injury,
death or property damage.
To remove a bolt-on main tank cover
1. Thoroughly clean the cover. Remove all dirt, grease and
moisture.
2. Relieve internal tank pressure by manually operating
the pressure relief valve.
3. Remove the hardware (3/8” inch nuts using a 9/16”
socket) which attaches the cover to the tank.
4. Gently pry the cover upward, making sure that the
cover gasket does not come in contact with the
transformer insulating liquid. Lift vertically to prevent
damage to cover, bolts, and tank gasket.
5. Remove the gasket sections from the tank flange,
noting the location and orientation (up/down) of each
piece.
To reinstall the bolt-on main tank cover
1. Return the gasket sections to their original positions
and orientation.
2. Reinstall the cover, using 25 ft-lbs. torque to tighten the
cover hardware. After installing all the nuts, re-torque
each nut to insure the proper torque is achieved.
3. Remove the pressure relief valve and pressurize the
headspace to insure that there are no leaks. The pres-
sure should not exceed 7 psig. The established pres-
sure should be maintained for at least four hours to
insure that all the seals are proper.
To remove a bolted-on manhole or handhole cover
1. Thoroughly clean the cover. Remove all dirt, grease and
moisture.
2. Relieve internal tank pressure by manually operating
the pressure relief valve.
3. Remove the hardware (3/8” inch nuts using a 9/16”
socket) which attaches the cover to the tank.
4. Gently pry the cover upward, making sure that the
cover gasket does not come in contact with the
transformer insulating liquid. Lift vertically to prevent
damage to cover, bolts, and tank gasket.
5. Remove the gasket sections from the manhole flange,
noting the location and orientation (up/down) of each
piece.
To reinstall the bolt-on manhole or handhole cover
1. Return the gasket sections to their original positions
and orientation.
2. Reinstall the manhole/handhole cover, using 25 ft-lbs.
torque to tighten the hardware. After installing all the
nuts, re-torque each nut to insure the proper torque is
achieved.
3. Remove the pressure relief valve and pressurize the
headspace to insure that there are no leaks. The pres-
sure should not exceed 7 psig. The established pres-
sure should be maintained for at least four hours to
insure that all the seals are proper.
4. Reinstall the access cover using 25 ft-lbs. torque to
tighten the access cover hardware.
WARNING
If the need arises to open a welded tank unit by cutting
welds, purge all gas space with nitrogen and keep
nitrogen flowing during cutting operations. Failure to do
so may cause gases to explode in the tank.
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Insulating liquid maintenance
Sampling insulating liquid
ote:N A sample of the liquid should be taken when the unit
is warmer than the surrounding air to avoid conden-
sation of moisture on the liquid. Liquid samples must
be drawn from the sampling valve located at the
bottom of the transformer tank.
Containers used for sampling liquid should be clean and dry
large mouth glass bottles.
Do not permit the fluid to splash into the receiving
container. Splashing can introduce air and moisture into
the fluid. Rinse the bottle three times with the liquid being
sampled. Make sure the liquid being sampled is representa-
tive of the liquid in the unit.
Test samples should be taken only after the liquid has
settled for some time – eight hours for a barrel, up to
several days for a large transformer. Cold insulating liquid
is much slower in settling. Liquid samples from the trans-
former should be taken from the sampling valve at the
bottom of the tank.
WARNING
Do not lower fluid in tank to a level below the top
of the core clamp. Insufficient fluid risks unit failure,
which could result in severe personal injury or death to
exposed personnel.
When sampling, a metal or non rubber hose must be used
because oil leaches the sulfur found in rubber. The presence
of sulfur can prove harmful to transformer components.
When drawing samples from the bottom of the transformer
or large tank, sufficient liquid must first be drawn off to
ensure that the sample will be from the bottom of the tank,
and not the liquid stored in the sampling pipe.
Testing insulating liquid
For testing the dielectric strength of insulating liquids,
follow the procedure specified by the American Society
for Testing Materials in ASTM D-877, "Standard Method for
Testing Electrical Insulating Oils."
If, at any time, the dielectric strength of the liquid drops
below 26 kV, it should be filtered until it tests at 26 kV or
better.
Filtering insulating liquid
Transformer oil, R-Temp fluid or Envirotemp™ FR3™ fluid
can be filtered by means of a filter press. The filter press is
effective for removing all types of foreign matter, including
finely divided carbon and small amounts of moisture. The
purifier equipment consists of a specifically proportioned
filter press, a positive volume gear pump, driving motor,
combined drip pan and mixing tank, necessary piping,
valves, strainer, gauges and a drying oven.
Filtration should be continued until the dielectric test of the
insulating liquid is 26 kV or better.
CAUTION
When filtering any insulating fluid, the filtering
equipment must be free of contaminants and other
liquids. The presence of other liquids may alter the
physical and electrical characteristics of the fluid.
Applicable standards
1. IEEE Std C57.91™-2011 standard, "Guide for Loading
Mineral Oil Immersed Transformers."
2. IEEE Std C57.93™-2007 standard "Guide for Installation
and Maintenance of Liquid Immersed Power
Transformers."
3. IEEE Std C57.106™-2006 standard, "Guide for
Acceptance and Maintenance of Insulating Oil in
Equipment."
4. ASTM Specification #D 877, "The Standard Method of
Testing Electrical Insulating Oils."
5. IEEE Std C57.121™-1998 standard, “Guide for
Acceptance and Maintenance of Less Flammable
Hydrocarbon Fluid in Transformers.”
R-Temp fluid-filled transformers
Periodic maintenance tests for R-Temp fluid-filled
transformers should be performed on essentially the same
schedule as would be used for conventional mineral oil-filled
transformers of similar application. The same type of
sampling techniques should be used. Basic recommended
tests for R-Temp fluid-filled transformers are dielectric
strength, moisture content, and flash and fire point.
Dielectric strength
Although the transformer should operate satisfactorily
with a fluid dielectric strength of 22 kV, an R-Temp fluid
dielectric strength below 25 kV is an indication of excessive
contamination. In this case, the R-Temp fluid should be
replaced or filtered to remove the moisture or particulate
contamination.
The dielectric strength of R-Temp fluid should be tested in
accordance with ASTM D 877.
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Flash and fire points
Relatively small percentages (2-3%) of transformer oil or
contaminants may substantially reduce the flash and fire
point of R-Temp fluid. If it is suspected that the fluid may
have been exposed to contamination, the flash and fire
point should be measured in accordance with ASTM D-92.
A fire point lower than 300°C probably indicates some
contamination by lower fire point material. If flash or fire
points fall below the minimum values required, retrofilling
may be required.
Drain and refill
If it is necessary to drain and refill the transformer, special
care should be taken to avoid the entrapment of gas
bubbles in the system. Sufficient time should be allowed
between refilling and energization of the transformer to be
sure that any gas bubbles created during the process have
dissipated.
Contact your Eaton representative for additional handling
guidelines.
PEAK™ and Envirotemp™ FR3™ fluid-filled
transformers
Periodic maintenance should be performed on the
same schedule as would be used for units of similar
application filled with transformer oil. The same type of
sampling techniques should be used (ASTM-D923). Basic
recommended tests for Envirotemp™ FR3™ fluid are
dielectric strength, moisture content and flash and fire
points.
Acceptance values should meet or exceed those shown in
IEC 61203, "Guide for Maintenance of Transformer Esters in
Equipment".
CAUTION
When the insulating fluid temperature is less than –10ºC
(14ºF), no-load tap changers and energized loadbreak
switches should not be operated and the Bay-O-Net
fuses should not be used to make or break a load.
(Operations at lower temperatures may be possible
provided it is certified by the switching device
manufacturer for loadbreak operation in Envirotemp™
FR3™ fluid at lower temperatures.)
If the transformer cover or manhole must be removed
for internal service, exposure time to ambient air should
be minimal. Avoid exposure times greater than 24 hours.
Immediately after service is completed, replace the cover or
manhole. Then, purge and recharge the headspace with dry
nitrogen.
The procedure for recharging the headspace with nitrogen
should include the following steps:
1. Fill headspace with dry nitrogen to a pressure of 2-3
psig.
2. Vent headspace to atmospheric pressure.
3. Refill headspace with nitrogen to 2-3 psig.
4. Verify that the unit is hermetically sealed.
If the manhole cover or non-flapper style Bay-O-Net fuses
are removed for more than 24 hours, any oxygen absorber
packet(s) should be replaced.
Transformer oil contamination
Envirotemp™ FR3™ fluid is fully miscible with oil. There
is no known detrimental performance impact when
Envirotemp™ FR3™ fluid is mixed with mineral oil.
Conversely, except for some reduction in flash and fire
points, the same is true for oil mixed in with Envirotemp™
FR3™ fluid. More than 7% mineral oil in Envirotemp™
FR3™ fluid is required to drop the fire point to below
300ºC. To maintain its exceptional environmental
classification, contamination of Envirotemp™ FR3™
dielectric coolant by any other fluids should be avoided.
Contact your Eaton representative for additional handling
guidelines.
Spare parts and service
We suggest that you keep one spare set of gaskets for
the manhole and any gasket-type bushings used. Other
renewal parts may be ordered through your local factory
representative. When replacing components, including
gaskets, on a PEAK transformer ensure they are rated for
PEAK level operating temperatures. When ordering parts or
requesting service, provide a complete description of the
part or the problem and the complete transformer serial
number as listed on the nameplate.
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Preventative maintenance instructions If any issues are found regarding the below, contact PS-WarrantyServices@
Eaton.com for assistance on transformers under warranty. Additionally, these
reports must be available upon request to maintain warranty period.
Transformer Exterior Maintenance
Items to Inspect Points to be Checked Remedial Action Frequency
Exterior Surfaces Inspect for evidence of tampering, battered metal,
gouges, etc. Check for any damage that would
allow the entrance of wires or other metallic
devices.
Any such damage should be repaired
immediately.
Annual
Paint or Protective Coatings Inspect for scratches or weathering. Any such damage should be touched up
immediately.
Annual
Tank Leaks Check tank exterior for signs of a leak. Any such leaks should be repaired immediately. Annual
General Location Check the area around the transformer for stored
tools, materials, equipment or debris.
Anything on or against the transformer should
be removed.
Annual
General Location Walk completely around unit and listen for
abnormal noises; should be a steady hum without
intermittent rattling
Any such abnormal noises should be reported
and investigated.
Annual
Pad Verify that pad has not tilted resulting in a
transformer that is more than 5° from horizontal.
If pad support is compromised or out of level
greater than 5°, repair it immediately.
Annual
Nameplates Abnormal or unexpected fading of nameplates or
decals.
Contact your Eaton representative for
replacement nameplates and decals as
necessary.
Annual
Unusual Odors Smells of fluid or burning. This could be indicative
of an unseen leak under the base. Also, inspect the
concrete around the perimeter of the transformer
base for oil spotting.
Any such abnormal odors should be reported
and investigated.
Annual
Cabinet Interior Maintenance
Items to Inspect Points to be checked Remedial Action Frequency
Gauges and Controls Check for proper operation. Repair or replace damaged or defective
equipment.
Annual
Equipment Leaks Inspect drain cocks, plugs, fuse mountings, and
switches. Look for evidence of insulating liquid
seepage around tank-wall gaskets, seals, etc.
Repair as required. Replacement of gaskets or
seals in the tank wall may require that the tank
be opened and the insulating liquid lowered
to the appropriate level. For instruction on
opening the tank and for draining and replacing
the insulating liquid, refer to the Insulating
Liquid Maintenance section.
Annual
Tank Pressure Check that pressure/vacuum gauge does not
remain at zero for an extended period of time. It
is preferable that a given unit not cycle between
negative and positive pressures on a daily basis.
Commissioning pressures have been documented
in a separate paper based on the top fluid
temperature. Any observed readings lower than -2
psig or greater than +7 psig indicate a condition
that can and should be corrected.
If the pressure/vacuum gauge remains at zero
for an extended period of time this may be
evidence of air leakage in and out of the tank.
A leak test should be performed by adding
nitrogen to the airspace and observing for loss
of pressure over an interval of a minimum of
12 hours. If the pressure is lost, locate the leak
and repair immediately.
Annual
WARNING
Hazardous voltage. Can cause severe injury, death, or
damage to equipment. De-energize transformer from
a remote upstream source before opening cabinet
and doing cabinet interior inspection or maintenance.
Check that all transformer terminals and bushings have
zero voltage. Ground transformer following industry
accepted safe grounding practices.
16 SubStation tranSformer inStallation and partS replacement information MN202002EN JUNE 2016