Eaton COOPER POWER SERIES User manual

COOPER POWER
SERIES
Distribution
Transformers
MN202001EN Effective August 2015
Supersedes S210-12-1 August 2013
Three-phase pad-mounted compartmental type transformer
installation and maintenance instructions

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.
ii Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

Contents
SAFETY INFORMATION
Safety Information .............................................................................iv
PRODUCT INFORMATION
Introduction ...................................................................................1
Acceptance and Initial Inspection...................................................................1
Handling ......................................................................................1
Storage .......................................................................................2
INSTALLATION INSTRUCTIONS
Installation Location .............................................................................2
Mounting the Transformer ........................................................................2
Pre-Service Inspection (Exterior) ...................................................................2
Pre-Service Inspection (Interior) ....................................................................3
External Connections ............................................................................4
ACCESSORIES
Liquid Level Gauge .............................................................................5
Liquid Temperature Gauge ........................................................................5
Pressure-Vacuum Gauge .........................................................................6
Pressure Relief Device ...........................................................................6
SWITCHES AND PROTECTIVE DEVICES
Bay-O-Net Fuse. ................................................................................7
Internal Cartridge Fuse ..........................................................................10
Internal Loadbreak Switches .....................................................................11
Tap-Changer ..................................................................................12
Dual-Voltage and Delta-Wye Switch ................................................................14
Vacuum Fault Interrupter (VFI) ....................................................................15
Air Switches (Arc Strangler™) ....................................................................16
Surge Arresters ...............................................................................17
MAINTENANCE
Exterior Maintenance ...........................................................................19
Cabinet Interior Maintenance .....................................................................19
Tank Internal Maintenance .......................................................................19
Tank Cover Removal and Installation ...............................................................19
Bushing Removal and Replacement................................................................22
Cabinet Removal and Installation ..................................................................22
Insulating Liquid Maintenance ....................................................................23
OPERATION
Operation ....................................................................................24
APPLICABLE STANDARDS
Applicable Standards ...........................................................................25
SPARE PARTS AND SERVICE
Spare Parts and Service .........................................................................25
PREVENTATIVE MAINTENANCE INSTRUCTIONS
Preventative Maintenance Instructions .............................................................26
iiiThree-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

iv
iv Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001ENEN August 2015
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
installation 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

Introduction
Eaton provides installation and maintenance instructions
for its Cooper Power™ series transformers in Service
Information MN202001EN. These transformers are designed
for installation on three-phase underground systems. All
units are constructed for weather-exposed mounting on a
concrete pad with high- and low-voltage cable entering the
operating compartments through an opening in the pad.
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 are not intended to 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
Receiving 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, inspect for signs of
damage or mishandling. Locate accessory parts that
may have been shipped separately.
3. If 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
destination, notify your Eaton representative. He or she
will, with the inspector’s report, take the necessary
steps to file a claim against the carrier.
Handling
Special procedures must be followed when handling
transformer in ambient temperatures below -20 °C. Contact
your Eaton representative for further instructions. Failure to
follow special handling procedures may cause premature
failure of transformer and its components.
Transformer weight
The transformer weight is shown on the transformer
nameplate. Most of the weight in a pad-mounted
transformer assembly is in the main tank that holds the core
and coil assembly and the insulating liquid.
Moving transformers shipped on pallets
Transformers shipped on pallets may be lifted or moved by
forklift trucks of proper capacity. When using a forklift, lift
with the transformer tank closest to the mast of the forklift
since most of the transformer weight is in the tank. Pallet-
mounted equipment may also be moved by crane or hoist.
Lifting transformers by crane or hoist
Check the weight of the transformer and the capacity and
condition of all hoisting or lifting equipment. Do not use
worn, frayed or damaged cables or slings. Do not use
hoisting machinery with load capacity less than the weight
of the transformer. Improper use of hoist or jack could
seriously damage the transformer or its attachments or
cause serious personal injury.
For unloading, lifting lugs are provided near the top of the
transformer tank. Lifting chain or cable 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 lugs.
Do not attempt to lift the transformer by placing a
continuous loop of chain or cable around the unit or lifting
lugs. This can damage the transformer and can cause
accidents resulting in serious personal injury.
If the transformer cannot be lifted by crane, it may be
skidded or moved by rollers.
Using jacks
Place jacks under the tank base on the open ends of the
transformer tank. Jacking pads are provided for transformers
with bases greater than 6”. Do not place jacks under
radiators or terminal compartment frames.
When jacking a transformer for insertion of rollers
underneath it, ensure that four jacks are used and that two
adjacent corners are raised simultaneously and evenly to
avoid warping the base. When using rollers, use as many as
necessary to distribute the weight uniformly.
Do not attach pulling lines to moldings or other sheet metal
parts of the transformer.
IMPORTANT
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.
WARNING
Heavy Equipment. Improper handling can cause severe
injury, death, or damage to transformer. Before moving
the transformer, read the handling instructions provided
in this manual.
1Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

Storage
Transformers that will not be placed in service immediately
should be stored with terminal compartment doors closed
and sealed to prevent damage to bushings or other
attachments.
Quality standards
ISO 9001 certified quality management system
Installation
Installation location
The transformer must be located to meet applicable fire
codes. For indoor installations, the installation location must
meet the requirements of the National Electrical Code
(NEC®) with sufficient space requirements and proper over-
current protection as specified by the listing body that has
jurisdiction over the installation.
These pad-mounted 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 Eaton representative.
Mounting the transformer
The transformer should be mounted on a level concrete
pad. The pad should be strong enough to support the
weight of the transformer. The site must be adequately
prepared to prevent the transformer from tilting beyond two
degrees from horizontal.
Tilting beyond two degrees may cause internal components
to come out of the oil and/or cables to mechanically stress
the bushings and bushing gaskets. Excessive tilt (beyond
two degrees) can result in a lower dielectric strength for the
transformer than the basic insulation level (BIL) listed on the
nameplate. Reduced BIL can result in an internal dielectric
breakdown with a risk of explosion, tank rupture, or fire.
To maintain full cabinet security, the transformer tank and
cabinet base have provisions for installing cleats to secure
transformer to pad. If gaps still exist between the cabinet
and pad after cleating the cabinet, the installation will not
provide the security needed to prevent tampering by the
public. Add a permanent mortar seal to fill the gaps.
Pre-service inspection (exterior)
New transformers, or transformers which are being
activated after a period of storage, should be thoroughly
inspected before being connected to the power distribution
system to identify damage which may have occurred during
storage.
1. The transformer exterior should be inspected for nicks,
dents, and scratches. Repair damage to weather-
resistant finishes promptly.
2. The tank cover and manhole/handhole cover seals
and all gaskets or seals at bushings, gauges, fuses,
operating devices, etc., should be inspected for
evidence of insulating liquid seepage. Repair leaking
or improperly tightened gaskets and seals before the
transformer is placed in service.
3. Under normal conditions, the transformer leaves the
factory with a slight positive pressure in the tank
over the oil. However, due to changes in atmospheric
conditions, the unit may arrive under vacuum (negative
pressure). This is itself is not cause for concern, however
continued absence of either negative or positive
pressure may indicate a leak at a gasket seal or tank
seam, and require further investigation. To leak test
transformer, remove the pressure relief valve (see Figure
1) and pressurize the headspace to ensure that there are
no leaks. The test pressure should not exceed 7 psig.
The established pressure should be maintained for at
least four hours to ensure that all the seals are proper.
Figure 1. Pressure relief valve.
WARNING
Fire Hazard. Non-level installation of transformer
can result in fire and cause severe personal injury or
death. Prepare transformer installation site such that
transformer does not tilt more than two (2.0) degrees
from horizontal while the transformer is in service at
the site.
2Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

4. The liquid level inside the tank must be checked (see
Insulating Liquid Maintenance section of this manual).
On transformers equipped with a liquid level gauge,
the liquid level may be read directly from the gauge.
On transformers that are not gauge equipped, the tank
liquid level must be determined by removing the liquid
level plug (see Figure 2). At 25 °C liquid temperature,
the liquid level should be at the bottom edge of the
liquid level plug hole.
If the tank temperature is greater than ambient air tem-
perature, the transformer tank must be vented to zero
pressure before the liquid level plug is removed. Failure
to do so may cause hot oil to be sprayed from the plug
hole and may result in severe personal injury.
5. Special procedures must be followed when
energizing a transformer in ambient temperatures
below -20°C. Contact your Eaton representative for
further instructions. Failure to follow special start-
up procedures may cause premature failure of the
transformer and its components. Also, note warning
and caution statements in Switches and Protective
Devices section of this manual for further precautions
when operating under-oil loadbreak accessories in
insulating liquid temperatures below 0°C.
Pre-service inspection (interior)
Pre-service interior inspection may not be required if
exterior inspection reveals no evidence of damage.
If interior inspection is required, the transformer must be
opened by removing the manhole/handhole or tank cover.
See the Tank Cover Removal and Installation section of
this manual.
Pre-service interior inspections should be restricted to
noting defects or damage that may prevent proper operation
of the transformer.
Inspect for:
1. Moisture on underside of the tank cover or man-hole
cover.
2. Loose, shifted, or damaged parts (bushings, fuse
holders, etc.).
3. Broken or loose connections.
4. Contaminated insulating liquid (sediment or foreign
objects on the tank bottom, dirt or air bubbles
suspended in the liquid).
Internal damage
If concealed internal damage is suspected, it may be
necessary to lower the insulting liquid level to complete the
inspection. Refer to the Insulating Liquid Maintenance
section of this manual.
Contaminated insulating liquid
If moisture is found inside the tank, or there is evidence
that the insulating liquid may be otherwise contaminated, a
liquid sample should be taken for analysis. Samples should
be drawn from the bottom of the tank. For instruction on
sampling the insulating liquid please see the Insulating
Liquid Maintenance section of this manual.
If moisture is present in the liquid, the transformer must
be dried out. Contact your Eaton representative for special
instructions on dry-out or other decontamination processes.
CAUTION
Elevated Pressure. Can cause severe personal injury.
Do not remove liquid level plug (see Figure 2) before
venting transformer to zero pressure. Pull ring on
pressure relief valve to relieve pressure.
Figure 2. Liquid level plug.
WARNING
Fire Hazard. Energizing transformer in ambient
temperatures below -20 °C can result in fire and cause
severe personal injury or death. Contact your Eaton
representative for further instructions on energizing
transformer in ambient temperatures below -20 °C.
CAUTION
Before opening the transformer tank for Pre-Service
Inspection, read the Insulating Liquid Maintenance
section in this manual. This section explains safety
precautions that should be taken and gives instructions
on how to prevent insulating liquid contamination.
3Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

External connections
Transformers that require no internal inspection or repair
may be connected to the system. Transformers must be
connected and operated as indicated by the transformer
nameplate. Clean bushings and terminals before making
connections. Remove dirt, grease or foreign material.
Contamination can cause failure of the bushings.
Cables connected to the transformer terminals are to have
sufficient flex to allow normal pad movement due to ground
freeze/thaw and settling. Insufficient cable flex may cause
premature failure of the bushings.
Ground connections
The transformer tank must be connected to a permanent,
low-resistance ground. If the tank is not solidly grounded
and the transformer is connected to the power distribution
system, then the tank should be regarded as energized.
An energized tank is extremely dangerous. Contact with an
energized tank can shock, burn, or cause death.
Three-phase pad-mounted transformers are equipped with
two grounding pads for making the ground connection.
The pads (see Figure 3) are located on the faceplate of the
transformer behind the terminal compartment doors. One
pad is in the primary compartment and the other in the
secondary compartment.
Grounded wye-grounded wye transformer
connections
Grounded wye-grounded wye winding connection
transformers are designed for power distribution systems
that have a grounded neutral connector. All windings
designed for grounded neutral operation must be
permanently and solidly grounded to the system neutral
without electrical resistance.
High voltage connections
Make connections as shown in the diagrams and
information on the transformer nameplate. Transformer
neutrals must be connected to system neutrals. Leads
and connections that are not used must be insulated from
ground and all other leads.
Livefront transformer connections
Externally clamped porcelain bushings are normally provided
for high voltage connection to three-phase pad-mounted
livefront transformers. The bushings have tin-plated
eyebolt terminals suitable for both copper and aluminum
conductors. The bushings are positioned to allow vertical
takeoff of primary cables entering from below.
Deadfront transformer connections
Deadfront three-phase pad-mounted transformers are
equipped with universal bushing wells, one-piece bushings,
or bushing wells with factory-installed inserts. Universal
bushing wells must be field equipped with bushing well
inserts before loadbreak cable connections can be made.
Bushing well inserts must be compatible with the universal
bushing well. Use of improperly rated inserts can cause
premature failure of the transformer or its components.
Read the manufacturer’s instructions furnished with the
inserts before installing to determine if they are compatible.
Low voltage connections
Spade terminals are the standard low voltage connectors
used for three-phase pad-mounted transformers. The low
voltage bushings are externally clamped to the transformer
tank wall.
WARNING
Hazardous voltage. Can cause severe injury, death, or
damage to equipment. Ground transformer following
industry-accepted safe grounding practices before
making other electrical connections. De-energize
power distribution wires that will be connected to
transformer. Verify that wires are de-energized at the
transformer before connecting to transformer.
Figure 3. Grounding pad.
4Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

Accessories
Three-phase pad-mounted transformers can be equipped
with a variety of optional equipment. Most such accessories
are factory installed and no fieldwork is required to prepare
them for operation.
Liquid level gauge
Transformers may be furnished with a liquid level indicator
as optional equipment 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.
The gauge may have one or two SPDT (Single Pole Double
Throw) alarm contacts to give a remote annunciation of
low liquid level. For wiring and contact ratings, refer to the
schematic furnished with the transformer.
Liquid temperature gauge
Transformers may be furnished with a temperature gauge
as optional equipment to indicate the top liquid temperature
in the tank in degrees Celsius. The temperature-sensitive
element is mounted in a leak-proof well, permitting removal
of the thermometer without lowering 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 may have two SPDT contacts for
energizing a fan circuit or for a high temperature alarm. For
wiring and contact ratings, refer to the schematic furnished
with the transformer.
Figure 4. Liquid level gauge.
Figure 5. Liquid temperature gauge.
5Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

Pressure-vacuum gauge
Transformers may be furnished with a pressure-vacuum
gauge as optional equipment to indicate 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.
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 transformer may have 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.
Pressure relief device
Transformers may have a cover-mounted pressure
relief device (PRD) in addition to the faceplate-mounted
pressure relief valve (PRV) standard on all three-phase pad-
mounted designs. 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.
The PRD may have SPDT alarm contacts for remote
signaling of device activation. For wiring and contact ratings,
refer to the schematic furnished with the transformer.
Figure 6. Pressure-vacuum gauge. Figure 7. Pressure relief device.
CAUTION
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.
6Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

Switches and protective devices
Bay-O-Net fuse
Eaton’s Cooper Power series Bay-O-Net fuse assemblies are
used to protect transformers and distribution systems. The
assemblies are mounted on the faceplate of pad-mounted
transformers and combine the ease of hotstick operation
with the safety of deadfront construction (see Figure 8).
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.
WARNING
Hazardous voltage. Can cause severe injury, death, or
damage to equipment. Use a hotstick to service a Bay-
O-Net fuse. Do not install a Bay-O-Net fuse to complete
an electrical circuit if a fault condition is suspected.
Do not re-energize suspected failed equipment. After
installing Bay-O-Net fuse, energize transformer from a
remote upstream source.
FUSEHOLDER
LATCH HANDLE
FUSE
CARTRIDGE
HOLDER
FUSE
LINK
FUSE
CARTRIDGE
END PLUG
GASKET SEAL
CONTACT
FLARE
TULIP
TIP
Figure 8. Bay-O-Net fuse assembly.
7Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

A Bay-O-Net fuse is not recommended for fault closing.
Do not re-energize suspected failed equipment; serious
personal injury may result. Internal fault conditions can
cause the transformer to rupture or the cover to blow off.
Always energize transformer from a remote upstream
source.
When replacing a blown fuse, the feed circuit should be
opened and closed from a remote location. The Bay-O-Net
fuse should be replaced using the procedure described
below and re-energized from a remote upstream source. If
equipment is re-fused while energized, the fuse could close
in on the system’s maximum fault current. Any equipment
that has a suspected failure should not be closed in with
the fuse.
For additional information on Eaton’s Cooper Power series
Bay-O-Net fuse assembly, including loadbreak ratings,
refer to catalog section CA132015EN, Service Information
MN132003EN, and Service Information MN132002EN.
Current sensing, dual sensing, dual element, and high
ampere overload links can be used in a Bay-O-Net fuse
assembly. For additional information on these links, including
interrupting ratings, see catalog sections CA132009EN,
CA132010EN, CA132011EN, and CA132007EN respectively.
Bay-O-Net fuse re-fusing instructions
Remove fuse holder
Step 1 - Relieve tank pressure.
Use a hotstick to perform the following steps:
1. Pull ring on pressure relief valve to open valve. Hold the
valve open for 30 seconds after pressurized air can no
longer be heard hissing through the valve.
2. Close pressure relief valve and wait 30 seconds.
3. Pull pressure relief valve open. Hold the valve open until
hissing stops, and then for another 5 seconds. Pulling
the valve open again allows any residual pressure to be
released from tank.
Step 2 - Unlock fuseholder and break seal.
Use a hotstick to perform the following steps:
1. Stand to one side of the Bay-O-Net being removed.
2. Attach hotstick to fuseholder eye.
3. Twist hotstick to unlock fuseholder (see Figure 9).
4. Turn fuseholder 90° in the Bay-O-Net housing to break
seal between seal gasket and Bay-O-Net housing (see
Figure 10).
Step 3 - Draw fuseholder out.
Use a hotstick to perform the following steps:
1. Draw fuseholder out quickly 8 to 10 inches to interrupt
load (see Figure 10).
2. Wait several seconds for fluid to drain from fuseholder.
Step 4 - Remove fuseholder from Bay-O-Net housing.
1. Remove fuseholder from Bay-O-Net housing.
2. Wipe off fuse cartridge holder and fuse cartridge (see
Figure 11).
Figure 9. Unlock and turn fuseholder 90° in the Bay-O-
Net housing.
CAUTION
If tank pressure has not been released, the fuse holder
may be forced out of the Bay-O-Net housing. Maintain
control of fuse holder at all times.
CAUTION
If fluid is coming out of the Bay-O-Net assembly, open
the pressure relief valve again to equalize pressure
inside the tank.
8Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

Replace fuse link
A separate replaceable fuse link, fuse cartridge, and
end plug are available for all Eaton Bay-O-Net fuses
except catalog numbers 4000358C16CB and C18CB,
4038361C03CB, C04CB, C05CB, and solid link
4038361C10CB. These catalog numbers are integral
assembles which include the link, cartridge and end plug.
For the above listed integral assemblies follow Step 5 and
then tighten new cartridge/fuse/end plug against fuse holder
using 50 to 70 in-lbs. torque; then, proceed to Step 9. For all
other Bay-O-Net fuses, follow Steps 5 through 9.
Step 5 - Remove fuse cartridge.
Use a 3/4 inch wrench to remove fuse cartridge from fuse
cartridge holder (see Figure 12).
Step 6 - Remove end plug and fuse link from fuse cartridge.
1. Use 3/4 inch and 1/2 inch wrenches to remove end plug
(see Figure 13).
2. Use screwdriver or other tool to straighten tulip tip end
of fuse link and push fuse link out of fuse cartridge.
Replace fuse cartridge if damaged.
Step 7 - Insert replacement fuse link into fuse cartridge
(see Figure 14).
1. A slight resistance may occur when inserting fuse link
into cartridge.
2. If the catalog number of the fuse being replaced is not
known, consult specifications or contact your Eaton
representative. Fuse catalog numbers may also be
indicated on the transformer door and/or nameplate.
Figure 10. Draw fuseholder out 8 to 10 inches.
Figure 11. Remove fuseholder from Bay-O-Net housing
and wipe clean.
Figure 12. Remove fuse cartridge holder.
Figure 13. Remove end plug from fuse cartridge.
9Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

Step 8 - Tighten cartridge to fuse cartridge holder.
1. Tighten fuse contact flare end against fuse cartridge
holder using 50 to 70 in-lbs. torque.
2. Replace end plug on the other end of fuse cartridge
and tighten to 50 to 70 in-lbs. torque.
3. Remove end plug and ensure that petals of tulip tip
have spread uniformly.
4. Replace end plugs, applying 50 to 70 in-lbs. torque to
both connections.
Step 9 - Install fuse holder.
Use a hotstick to perform the following steps.
1. Pull pressure relief valve, holding it open until hissing
stops, and then for another five seconds.
2. Attach end of fuseholder assembly to hotstick and
insert holder assembly firmly into Bay-O-Net housing.
3. Twist locking handle so that latch engages Bay-O-Net
housing’s shoulder, and steel washer seats tightly on
end of tube of Bay-O-Net holder assembly.
Internal cartridge fuse
Internal cartridge fuses are “weak link” expulsion-type fuses
used to protect transformers and distribution systems.
Internal cartridge fuse assemblies are mounted inside
the transformer tank and are compatible for use in many
insulating liquids. See fuse manufacturer’s product literature
for maximum interrupting ratings.
Internal cartridge fuse replacement
1. Verify that tank is grounded. De-energize transformer
from a remote upstream source. Ground all bushings
and terminals.
2. Remove tank cover as outlined in Tank Cover Removal
and Installation section of this manual.
3. Locate cartridge fuse assembly (see Figure 15) on back
tank wall.
4. Carefully remove all nuts that attach wire leads to fuse,
making sure not to drop nuts into the transformer tank.
Note position of all nuts, flat washers, spring washers,
etc., so that they can be reinstalled in the same
locations.
5. Replace fuses as required. Reconnect leads and re-
install washers and nuts in original locations.
6. Re-install cover as outlined in Tank Cover Removal and
Installation section of this manual.
Figure 14. Insert replacement fuse link.
Figure 15. Cartridge fuse assembly.
CAUTION
Visually inspect entire fuseholder assembly to ensure it
is installed properly.
WARNING
Hazardous voltage. Can cause severe injury, death, or
damage to equipment. Turn off power to transformer
before servicing internal cartridge fuses. Ground
transformer following industry accepted safe grounding
practices.
10 Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

Internal loadbreak switches
It is recommended that remote energization be used
whenever possible. Operate loadbreak switches using
hotstick tool. After loadbreak switch is switched to “OPEN”
position, verify that transformer secondary terminals have
zero voltage and then ground the secondary terminals to
prevent transformer backfeed energization.
Two-position loadbreak switch
The operating mechanism of the Eaton’s Cooper Power
series two-position loadbreak switch employs a manually-
charged over-toggle stored spring assembly which
performs independent of operator speed. The spring-loaded
activating mechanism ensures quick loadbreak or loadmake
operations in less than one cycle. Incorporated into the
switch mechanism are internal stops that restrict the handle
orientation to only two positions: “OPEN” and “CLOSED”
(see Figure 16). The switch should be hotstick-operated and
will require 15 ft-lbs. minimum input torque to operate.
Refer to Catalog Section CA800019EN Two-Position Sidewall
(Horizontal) and Cover (Vertical) Mounted Loadbreak
Switches for two-position loadbreak switch ratings.
External visible loadbreak switch
The Eaton’s Cooper Power series external visible loadbreak
switch is a great way to verify isolation of internal transformer
circuitry. Having visual confirmation that the secondary
bushings are de-energized saves both time and money,
while providing an added safety feature. It is strongly
recommended that if breaking load with this switch, the
viewing window be fully covered and locked into place.
Viewing this switch during operation under load could be
dangerous to the human eye. The external visible loadbreak
switch is always shipped with a padlockable cover box. It is
also important to remember that even after breaking load, the
incoming high voltage cables are still live and dangerous.
Figure 16. Two-position loadbreak switch handle and
indicator plate.
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.
CAUTION
Always fully cover and lock external visible loadbreak
switch window during operation. Failure to cover and
lock this window could cause personal injury. Before
operating the on/off/ground switch, it is important to
ensure the transformer tank has been fully grounded.
Always check fluid temperature before operating
loadbreak devices.
11Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

Sectionalizing loadbreak switch
Eaton’s Cooper Power series sectionalizing loadbreak
switch rotates 360° in either direction for alternate source
selection. An externally-installed index plate prevents
rotation to positions other than the one desired. The
switch cannot be switched more than one position without
resetting the index plate.
A spring-loaded activating mechanism ensures quick
loadbreak action and positive contact engagement through
all positions. Switching can be accomplished in less than
one cycle, and should be performed with a hotstick. To
follow are operation examples for the two most common
sectionalizing switch configurations.
The following is a V-blade switch operation example (see
Figure 17):
If “A” is the feeder and it is desired to switch to “B” feeder,
then the V-blade switch can be rotated as follows:
1. Set index stop plate between “line A only” and “Open”.
2. Rotate switch handle counterclockwise to “Open”.
Transformer and loop conductor are now “Open”.
3. Move index plate between “Open” and “line B only”.
4. Rotate switch handle counterclockwise to “line B only”.
Transformer is now energized for “B” feeder.
The following is a T-blade switch operation example (see
Figure 18):
If “A” is the feeder and it is desired to switch to “B” feeder,
the T-blade switch can be rotated as follows:
1. Set index stop plate between “line A only” and “loop
thru transformer open”.
2. Rotate switch handle counterclockwise to “loop thru
transformer open”. The transformer is now “OPEN” and
the loop conductor is electrically connected.
3. Move index plate between “loop thru transformer
open”” and “line b only”.
4. Rotate switch handle counterclockwise to “line b only”.
The transformer is now energized for “B” feeder.
For switch ratings and additional switch configurations
refer to Catalog Section CA800005EN, Four-Position
Sectionalizing Loadbreak Switches.
Tap-changer
Transformers equipped with a tap-changer can be changed
from one operating voltage to another. The transformer
must be de-energized and grounded before the tap-changer
is operated. Operating voltages accessible through use of
the tap-changer are indicated on the transformer nameplate.
On most three-phase pad-mounted transformers equipped
with tap-changers, the tap-changer operating handle
is located on the faceplate in the high-voltage terminal
compartment.
The standard style of tap-changer will have a hotstick-
operable handle. There are two styles of tap-changer
with this type of handle, each requiring a slightly different
method for changing tap settings.
Figure 17. V-blade four-position sectionalizing switch
handle and index plate.
Figure 18. T-blade four-position sectionalizing switch
handle and index plate.
WARNING
Hazardous voltage. Can cause severe injury, death,
or damage to equipment. De-energize transformer
from a remote upstream source before operating non-
loadbreak tap-changers, dual-voltage switches, or
delta-wye switches.
12 Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

The tap-changer shown in Figure 19 can be switched to a
new tap position as follows:
1. Verify that tank is grounded. De-energize transformer
from a remote upstream source. Ground all bushings
and terminals before operating the tap switch.
2. Back out lock screw to clear index plate.
3. Rotate handle to desired position.
4. Secure handle in its new position by tightening lock
screw through index plate until it bottoms.
5. Padlocking may be accomplished through hole
provided.
The tap-changer shown in Figure 20 can be switched to a
new tap position as follows:
1. Verify that tank is grounded. De-energize transformer
from a remote upstream source. Ground all bushings
and terminals before operating the tap switch.
2. Back out lock screw to clear index plate.
3. Pull handle out to clear index plate.
4. Rotate handle to desired position and allow pointer to
drop into slot of index plate.
5. Secure handle in its new position by tightening lock
screw through index plate until it bottoms.
6. Padlocking may be accomplished through hole
provided.
On some transformers, tap-changers have a lever handle
(see Figure 21). A lock screw secures the handle at a
particular setting. Such tap-changers can be switched to a
new position as follows;
1. Verify that tank is grounded. De-energize transformer
from a remote upstream source. Ground all bushings
and terminals before operating the tap switch.
2. Back out lock screw to clear index plate.
3. Rotate handle to desired position.
4. Secure handle in its new position by tightening lock
screw through index plate until it bottoms.
Figure 19. Hotstick-operable tap-changer (Style I).
Figure 20. Hotstick-operable tap-changer (Style II).
Figure 21. Lever handle tap-changer.
13Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

Dual-voltage and delta-wye switch
Transformers equipped for dual-voltage or delta-wye
(reconnectable winding) operations usually have an
externally-operable switch mounted on the faceplate in the
high-voltage terminal compartment. Units combining dual-
voltage and delta-wye may have two separate switches.
The transformer must be de-energized and grounded
before dual-voltage or delta-wye switches are operated.
Attempting to change dual-voltage or delta-wye switches
on an energized transformer may result in damage to the
equipment and severe personal injury.
Dual-voltage windings are either connected in series (for the
higher voltage) or in parallel (for the lower voltage). Dual-
voltage and delta-wye switches have two positions. Switch
positions are identified on the transformer nameplate and
marked by corresponding numerals on the switch mounting
plate.
When dual-voltage or delta-wye switches are set to connect
transformer windings in parallel, tap-changers must be
in the position shown on the transformer nameplate.
Tap-changers cannot be used to adjust voltage when
transformer windings are connected in parallel. Improper
tap-changer settings will cause circulating currents in the
windings, which will damage the windings and cause failure
of the transformer.
To change dual winding switch settings:
The standard type of dual-voltage or delta-wye switch will
have a hotstick-operable handle (see Figure 22).
This type of dual-voltage or delta-wye switch can be
switched to a new position as follows:
1. Verify that tank is grounded. De-energize transformer
from a remote upstream source. Ground all bushings
and terminals before operating dual-voltage or delta-
wye switch.
2. Back out lock screw to clear index plate.
3. Pull handle out to clear index plate and rotate handle
90°. Drop handle into new position.
4. Secure handle in its new position by tightening lock
screw through index plate until it bottoms.
5. Padlocking may be accomplished through hole
provided.
On some transformers, dual-voltage or delta-wye switches
have a lever handle (see Figure 23).
This type of dual-voltage or delta-wye switch can be
switched to a new position as follows:
1. Verify that tank is grounded. De-energize transformer
from a remote upstream source. Ground all bushings
and terminals before operating dual-voltage or delta-
wye switch.
2. Back out lock screw to clear index plate.
3. Rotate handle 90° to new position.
4. Secure handle in its new position by tightening lock
screw through index plate until it bottoms.
Figure 22. Dual-voltage/delta-wye switch (hotstick-
operable).
Figure 23. Dual-voltage/delta-wye switch (lever handle).
WARNING
Hazardous voltage. Can cause severe injury, death,
or damage to equipment. De-energize transformer
from a remote upstream source before operating non-
loadbreak tap-changers, dual-voltage switches, or
delta-wye switches.
CAUTION
Excessive current. Can cause damage to transformer
winding. When dual-voltage or delta-wye switches
are set to connect transformer windings in parallel,
tap-changers must be in the position shown on the
transformer nameplate.
14 Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

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 24. 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.
15Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015

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.
Air switches (Arc-Strangler®)
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.
16 Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015