Howard Industries HI-110 User manual

Document 2.4.128, Revision 3
October, 2017
1
Network Transformer Instruction Manual
Howard Industries
Distribution Transformer Division
Instructions (HI-110)
Installation, Operation, and Maintenance
of Secondary Network Transformers

Document 2.4.128, Revision 3
October, 2017
2
Network Transformer Instruction Manual
Read these instructions carefully and become familiar with the equipment before
proceeding with installation, operation, or maintenance activities. This equipment
contains extremely hazardous voltages. To prevent death, serious personal
injury, or equipment damage, all information in these instructions should be read
and observed. Safe use of this equipment is dependent on proper installation,
operation, and maintenance procedures.
Certain information in this manual is marked with the words DANGER, WARNING, or
CAUTION, which indicate hazards.
• DANGER indicates an imminently hazardous situation which, if not avoided, will
result in death or serious personal injury and may also result in damage to the
equipment.
• WARNING indicates a potentially hazardous situation which, if not avoided, could
result in death or serious personal injury and may also result in equipment
damage.
• CAUTION indicates a potentially hazardous situation which, if not avoided, could
result in minor or moderate personal injury and may also result in damage to the
equipment.
Personnel should not attempt to service this equipment until it has been effectively
de-energized, and all high-voltage and low-voltage bushing terminals have been
properly grounded. Only qualied personnel should install, maintain, and operate
this equipment. Qualied personnel are those who are trained in the installation,
maintenance, and operation of high-voltage equipment, trained in the proper use
of personal protective equipment (such as rubber gloves, safety glasses, protective
clothing, hard hats, etc.) and trained in appropriate rst aid procedures.
The instructions contained herein are intended to be a general guide for the
installation, operation and maintenance of this equipment, when operated in
“Usual Service Conditions” as dened in IEEE Standard C57.12.00. Although efforts
have been made to ensure accuracy and completeness, these instructions do not
address every conceivable application or circumstance that might be encountered.
Features presented herein may not be present in all equipment designs. Standard
and optional features are subject to change without notice. Howard Industries
makes no representation or warranty with respect to and assumes no responsibility
for the completeness, accuracy, sufciency, or usefulness of these instructions.
These instructions do not cover the installation, operation or maintenance of the
secondary network protector or any other accessory equipment installed by the
user. Users should refer to instructions provided by the manufacturer of such
equipment.
Questions regarding installation, operation, and maintenance, particularly when
encountering unusual or special circumstances not sufciently covered by these
instructions, should be directed to the Howard Industries Transformer Division.
READ THIS IMPORTANT SAFETY INFORMATION

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Network Transformer Instruction Manual
Table of Contents
SECTION 1: INTRODUCTION .............................................................................................................................5
SECTION 2: RECEIVING, HANDLING AND STORAGE ......................................................................................6
Drawings and Documents ...............................................................................................................................6
Lifting and Handling .........................................................................................................................................6
Initial Inspection................................................................................................................................................6
Fluid Levels........................................................................................................................................................7
Internal Inspection ...........................................................................................................................................7
Fluid Sampling...................................................................................................................................................7
Transformer Storage ........................................................................................................................................7
SECTION 3: INSTALLATION...............................................................................................................................9
Lifting and Handling .........................................................................................................................................9
Jacking ...............................................................................................................................................................9
Location and Mounting ....................................................................................................................................9
Grounding ........................................................................................................................................................10
Primary and Secondary Connections ............................................................................................................10
Primary Connections.......................................................................................................................................10
Secondary Connections..................................................................................................................................10
SECTION 4: INSPECTION AND TESTING ....................................................................................................... 11
Pre-Energization Inspection and Tests ......................................................................................................... 11
Continuity and Winding Resistance Test ...................................................................................................... 11
Ratio Test........................................................................................................................................................ 11
Insulation Resistance Test............................................................................................................................. 11
Tap Changer Setting....................................................................................................................................... 12
Series/Multiple and Delta/Wye Switch Settings.......................................................................................... 12
Grounding ....................................................................................................................................................... 12
Bolted Connections........................................................................................................................................ 12
Fluid Levels..................................................................................................................................................... 12
Fluid Temperature.......................................................................................................................................... 12
Current Transformers..................................................................................................................................... 12
Accessory Wiring ............................................................................................................................................ 12
Tank Finish...................................................................................................................................................... 12
Tools................................................................................................................................................................ 12
Internal Inspection ......................................................................................................................................... 12
Post-Energization Inspection and Tests........................................................................................................ 13
Verifying Correct Voltage................................................................................................................................ 13
Checking for Leaks......................................................................................................................................... 13
Observing Operation ...................................................................................................................................... 13
Checking Gauges ........................................................................................................................................... 13
Audible Sound ................................................................................................................................................ 13

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Network Transformer Instruction Manual
SECTION 5: OPERATION OF SWITCHING AND PROTECTIVE DEVICES ..........................................................14
Tap Changer .....................................................................................................................................................15
Series/Multiple or Delta/Wye Switch ............................................................................................................. 15
Primary Disconnect and Grounding Switch Computer Support..................................................................... 16
Three-Position Non-Interrupting Primary Disconnect and Grounding Switch ............................................... 16
Three-Position Mag-Break Primary Disconnect and Grounding Switch......................................................... 16
Sequential Grounding Provisions..................................................................................................................... 17
Phase Sequence Identication Provisions ..................................................................................................... 17
Network Protector ............................................................................................................................................. 17
Other Switching and Protective Devices.......................................................................................................... 17
SECTION 6: ACCESSORIES...............................................................................................................................18
Diagrammatic Nameplate ................................................................................................................................18
Fluid Level Gauge ............................................................................................................................................. 18
Fluid Temperature Gauge ................................................................................................................................18
Filler Plug and Upper Filter Press Connection................................................................................................. 18
Combination Drain and Bottom Filter Valve ....................................................................................................18
Terminal Chamber Vent and Level Plug...........................................................................................................18
Air Test Provision ...............................................................................................................................................19
Automatic Pressure Relief Valve and Pressure Relief Device .......................................................................19
Primary Entrance .............................................................................................................................................. 19
High-Voltage Bushings ..................................................................................................................................... 19
Secondary Bushings .........................................................................................................................................20
Current Transformers........................................................................................................................................20
Other Accessory Devices .................................................................................................................................. 20
SECTION 7: MAINTENANCE .............................................................................................................................. 21
Periodic Inspection............................................................................................................................................ 21
Inspection and Maintenance Checklist ........................................................................................................... 21
Electrical Testing ............................................................................................................................................... 22
Exterior Paint Finish ..........................................................................................................................................23
Fluid Leaks ........................................................................................................................................................23
Audible Sound Level..........................................................................................................................................23
Other Accessory Devices .................................................................................................................................. 24
Sampling and Testing the Fluid ....................................................................................................................... 24
Filtering the Fluid .............................................................................................................................................. 24
Removing or Lowering the Fluid....................................................................................................................... 24
Filling with Fluid ................................................................................................................................................ 24
Opening the Transformer Tank ........................................................................................................................ 25
Torque Guidelines .............................................................................................................................................25
Additional Maintenance Instructions .............................................................................................................. 27
Repair Parts ...................................................................................................................................................... 27
Warranty Claims ............................................................................................................................................... 27
Transformer Disposal ....................................................................................................................................... 27
TABLES
Table 1: Mag-Break Primary Switch Operation ............................................................................................... 16
Table 2: Sequential Grounding Switch Operation ........................................................................................... 17
Table 3: Torque Guidelines for External Cabinet Fasteners ........................................................................... 26
Table 4: Torque Guidelines for External Bushing Mounting Hardware ..........................................................26
Table 5: Torque Guidelines for External Bushing Terminal Connections.......................................................26
Table 6: Torque Guidelines for Accessories..................................................................................................... 27

Document 2.4.128, Revision 3
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Network Transformer Instruction Manual
This document is intended as a general guide for
the installation, operation and maintenance of
Howard Industries secondary network transformers.
Although efforts have been made to ensure accuracy
and completeness, these instructions do not address
every conceivable application or circumstance that
might be encountered. Features presented herein
may not be present in all transformer designs.
Standard and optional features are subject to
change without notice. Howard network transformers
are designed in accordance with IEEE Standard
C57.12.40, Secondary Network Transformers,
Subway and Vault Types (Liquid Immersed)-
Requirements.
The instructions contained herein are applicable
to transformers operated in normal conditions as
specied in the “Usual Service Conditions” section
of IEEE Standard C57.12.00. Questions regarding
installation, operation, and maintenance (particularly
when encountering unusual or special circumstances
not sufciently covered by these instructions) should
be directed to the Howard Industries Transformer
Division.
IT IS IMPORTANT TO READ AND COMPLY WITH
ALL SAFETY INFORMATION, INSTRUCTIONS AND
WARNINGS DISPLAYED THROUGHOUT THESE
INSTRUCTIONS BEFORE ATTEMPTING ANY
INSTALLATION, OPERATION, OR MAINTENANCE
ACTIVITIES.
SECTION 1: INTRODUCTION

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Network Transformer Instruction Manual
Drawings and Documents
Locate all shipping papers, packing lists, outline
drawings, and other pertinent information for use
during inspection. The transformer outline drawing
indicates the location of nameplates and provides
physical dimensions and weights. The nameplate
provides electrical characteristics, winding
connections, and weights. The wiring diagram
provides details of any control and alarm wiring that
might have been supplied.
Lifting and Handling
Lifting hooks are provided on the sides of the
transformer tank near the tank cover. All four lifting
hooks must be used simultaneously for lifting. The
transformer must not be lifted from any points other
than the provided lifting hooks. Do not use holes in
the lifting hooks for lifting. These holes are for tie-
down purposes only, and are not suitable for lifting.
Do not use the cover-mounted lifting eyes for lifting
the entire transformer, as these lifting eyes are
suitable for lifting the cover plate only.
Transformers should be lifted in an upright position,
allowing no more than 15 degrees of tilt from
vertical. Lifting cables should be no more than 20
degrees from vertical. Spreader bars should be used
to keep the lifting cables nearly vertical, enabling
a safe lift and reducing the likelihood of tank
deformation or damage to painted surfaces.
Lifting the transformer with a forklift is not
recommended, since weight and balance can be
problematic and radiator panels can be easily
damaged. Refer to the transformer nameplate
to determine the total weight of the assembled
transformer. Special care must be taken when
handling transformers when the ambient
temperature is below minus 20°C (minus 4°F);
otherwise, permanent damage to the transformer
may result.
Initial Inspection
Although all transformers, components, and
accessories are carefully inspected and tested
prior to shipment from the factory, a thorough
receiving inspection should be conducted to detect
any damage or loss that might have occurred after
shipment. The receiving inspection should be
completed upon receipt and before unloading from
the truck. Note any damage or discrepancies on the
bill of lading, le a claim with the carrier, and notify
the Howard Industries Transformer Division prior to
unloading the transformer and before attempting any
repair.
Before unloading the transformer, the following
checks should be performed:
1. Read the serial number on the transformer
nameplate and make sure it matches the
serial number listed on the bill of lading. Also,
check the nameplate for kVA rating, primary
voltage rating, secondary voltage rating,
impedance and other design characteristics,
and make sure they comply with the
specications.
2. Check shipping documents to make sure
the shipment is complete, including all listed
accessories and hardware. Be aware that
additional items may arrive on separate
pallets. Claims for shortages or errors
must be noted on the shipping documents
and reported immediately to the Howard
Industries Transformer Division. Failure to
make a timely claim will constitute unqualied
acceptance and a waiver of all such claims by
the purchaser.
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR
SERIOUS PERSONAL INJURY AND MAY ALSO
RESULT IN DAMAGE TO THE EQUIPMENT.
• Use a crane, suitable lifting cables or
straps, and a spreader bar to unload the
transformer.
• Do not unload using a forklift. Keep
unnecessary personnel clear while
unloading and moving the transformer.
SECTION 2: RECEIVING, HANDLING AND STORAGE

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Network Transformer Instruction Manual
3. Check the main tank, primary switch
chamber and primary terminal chamber for
indication of uid leaks, looking carefully at
weld seams, bushings, gauges, valves and
all other main tank and chamber ttings. If
suspicious indications are found, investigate
thoroughly to determine if a leak does exist
on the transformer. Indications of a leak
can sometimes be residual uid that was not
cleaned during the manufacturing process
and not an actual leak. In many cases a small
pinhole tank leak or leak from a bushing,
gauge, valve or other tting can be easily
repaired on site. Refer to the “Maintenance”
section for information about the repair of
uid leaks.
4. Check for external damage including dents or
scratches on the main tank walls, radiators,
primary switch chamber and primary terminal
chamber. Dents and scratches can often
be repaired on site using simple touch-up
procedures. If touch-up painting is performed,
do not remove or obscure any warning labels,
instructional labels or nameplates.
5. Check for broken, cracked, or damaged
bushings, gauges, valves and other ttings
and accessories.
6. Check for missing or damaged component
parts that may have shipped separately from
the transformer.
Fluid Levels
The transformer and primary switch chamber are
shipped from the factory with insulating uid lled
to the proper level. When provided, the primary
terminal chamber is also lled with uid at the
factory when the transformer is equipped with dead-
front separable insulated bushings or bushing wells.
Before energizing the transformer, verify proper uid
levels by observing the uid level gauges. The uid
level gauge pointer should be between the “High”
and “Low” mark, and point approximately at the
25°C mark.
A transformer found to have a low uid level
should be checked for potential leaks, repaired as
necessary and lled to the proper level with the
same type of liquid as specied on the transformer
nameplate. If uid must be added, refer to “Filling
with Fluid” for instructions.
Internal Inspection
An internal inspection of the transformer is rarely
necessary and is recommended only when there
are obvious indications that the transformer
has received severe impact damage during
transit. Do not open the transformer main tank
without authorization from the Howard Industries
Transformer Division. If the transformer main tank
must be opened, refer to “Opening the Transformer
Tank” for instructions.
Fluid Sampling
Sampling and testing of the uid is not required
unless there is an indication that moisture or
other contaminants have accidently entered the
main tank, switch chamber, or terminal chamber
during transit. If moisture or contaminants in the
uid are suspected, contact the Howard Industries
Transformer Division immediately for instructions.
If uid sampling is required, refer to “Sampling the
Fluid” for instructions.
Transformer Storage
Transformers can be temporarily stored if properly
prepared. It is recommended that transformers
be stored completely assembled. Prior to storage
transformers should be thoroughly inspected as
described above in the “Initial Inspection” section.
If the transformer is not completely assembled,
separate components and accessories should be
stored in a clean dry area in their original shipping
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS BELOW
COULD RESULT IN DEATH OR SERIOUS PERSONAL
INJURY AND MAY ALSO RESULT IN DAMAGE TO
THE EQUIPMENT.
• Do not energize the transformer if the uid
level is low.
• Maintain proper uid level while the
transformer is energized.

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Network Transformer Instruction Manual
containers. Do not store the transformer in a
corrosive environment.
If the transformer is to be stored for an extended
period of time before being placed into service,
it should be stored on a rm level surface. The
gas space above the insulating uid should be
pressurized with dry nitrogen to a pressure of 2-3
PSIG. This will prevent a negative internal pressure
that might draw moisture into the main tank, switch
chamber, or terminal chamber. Prior to storage, be
sure that the primary bushings or bushing wells
are tted with their protective dust covers, and the
secondary throat shipping guard is installed.
The transformer should be inspected periodically
while it is in storage. Ensure that an effective
pressure seal is maintained, and check for leaks
and corrosion. Any damage or defect should be
repaired immediately.

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Network Transformer Instruction Manual
Lifting and Handling
Lifting hooks are provided near the top of the
transformer tank for lifting. All four lifting hooks
must be used simultaneously. The transformer must
not be lifted from any points other than the provided
lifting hooks. Do not use holes in the lifting hooks for
lifting. These holes are for tie-down purposes only
and are not suitable for lifting. Do not use the cover-
mounted lifting eyes for lifting the entire transformer,
as these lifting eyes are suitable for lifting the cover
plate only.
Transformers should be lifted in an upright position,
allowing the transformer to tilt no more than 15
degrees from vertical. Lifting cables should be
no more than 20 degrees from vertical. Spreader
bars should be used to keep the lifting cables
nearly vertical, enabling a safe lift and reducing the
likelihood of tank deformation or damage to painted
surfaces.
Lifting the transformer with a forklift is not
recommended, since weight and balance can be
problematic and radiator panels can be easily
damaged. Refer to the transformer nameplate
to determine the total weight of the assembled
transformer. Special care must be taken when
handling transformers when the ambient
temperature is below minus 20°C (minus 4°F);
otherwise, permanent damage to the transformer
may result.
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR SERIOUS
PERSONAL INJURY AND MAY ALSO RESULT IN
DAMAGE TO THE EQUIPMENT.
• Use a crane, suitable lifting cables or
straps, and a spreader bar to unload the
transformer.
• Do not unload using a forklift.
• Keep unnecessary personnel clear while
unloading and moving the transformer.
Jacking
The transformer base is designed for jacking. Do
not use radiator ns, bushings, valves, gauges or
sheet metal surfaces for jacking. Jacking must
be done using the proper jacking provisions from
two adjacent corners simultaneously to prevent
warping of the tank bottom. Do not allow the jack to
come into contact with panel radiators. Refer to the
transformer outline drawing for the total weight of
the assembled transformer.
Location and Mounting
Consult local and national codes to ensure that
the installation meets all applicable requirements.
Location of the transformer must permit it to operate
in conditions that meet the requirements specied
in the “Usual Service Conditions” section of IEEE
Standard C57.12.00. Operation not meeting these
service condition requirements will compromise
transformer capacity and reliability, unless the
transformer is designed specically for operation
in conditions other than usual service conditions.
Contact the Howard Industries Transformer
Division, if additional information is needed about
location and mounting issues not covered by these
instructions.
The transformer should be mounted on a level
concrete foundation of sufcient strength to support
the weight of the completely assembled transformer
including the network protector and any other
attached accessories. The transformer should sit
ush with the surface of the mounting surface, so
that the transformer’s weight is evenly distributed.
The installed transformer should not tilt in any
direction more than three degrees. Greater tilt may
compromise insulation uid coverage of live parts
and may prevent insulating uid from circulating
properly through the cooling radiators. Improper
circulation of insulating uid may cause overheating
and result in reduced transformer life.
When network transformers are installed in vaults or
compartments, it is necessary to provide adequate
ventilation. The amount of air ow necessary will
SECTION 3: INSTALLATION

Document 2.4.128, Revision 3
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Network Transformer Instruction Manual
depend on the transformer kVA, efciency and
load cycle. Forced ventilation may be required
to adequately cool the transformer. Refer to the
National Electric Code for recommended vault
ventilation.
Before placing the transformer in service, remove
any shipping braces and packing material that may
have been attached at the factory.
Grounding
The transformer must be permanently grounded
according to applicable local and national codes.
Ground the transformer by using the grounding
provisions located on the exterior surface of the main
tank. Do not use hold-down bolts, pipe connections
or any other ttings for ground connections. A proper
low-resistance ground is critical for safe operation.
Transformers with a grounded-wye primary winding
and a wye secondary winding are designed for
electric distribution systems that have a grounded
neutral. All windings designed for grounded neutral
operation must be permanently and solidly grounded
to the system neutral.
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR
SERIOUS PERSONAL INJURY AND MAY ALSO
RESULT IN DAMAGE TO THE EQUIPMENT.
The transformer must be properly grounded
at all times.
Primary and Secondary Connections
Before making primary and secondary connections,
check to make sure that all mating connector
surfaces are clean and smooth. Connections must
be tightened appropriately to prevent overheating
and possible subsequent failure of the connection.
Refer to Table 5 for torque recommendations.
Connections should be made with care to avoid
placing undue stress on the bushings.
Primary Connections
Network transformers are supplied with a high-
voltage entrance as specied by the user, usually
consisting of dead-front bushings or wiping sleeves
for connection to the high-voltage source. Dead-
front bushings may be one-piece (integral) bushings
or universal wells with or without factory-installed
inserts. One-piece (integral) bushings and bushing
inserts are designed to interface with insulated
elbow connectors, and can be supplied for either
load-break or non load-break operation.
When transformers are supplied with bushing
wells only, inserts must be installed in the eld
before cable connections can be made. Bushing
well inserts must be compatible with the universal
bushing well. Do not use incompatible or improperly
rated inserts, or equipment damage might occur.
When installing bushings or cable accessories,
follow the installation instructions provided by the
equipment manufacturer.
Secondary Connections
Network transformers are normally supplied with
provisions for connection to a network protector.
These provisions consist of three externally-
replaceable bushings bolted to the main tank within
the secondary throat, three exible connectors for
electrical connection to the network protector, and
a secondary neutral pad welded to the main tank.
When a fully-insulated neutral bushing is provided, it
must be effectively grounded to the system neutral
for proper operation.
SECTION 4: INSPECTION AND TESTING

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Network Transformer Instruction Manual
BEFORE AND AFTER INITIAL ERGIZATION
Pre-Energization Inspection and Tests
After the transformer has been installed, but before
it is energized, the following tests and checks should
be performed at a minimum to ensure that the
transformer is ready to be energized. Do not energize
the transformer without performing these tests and
checks.
1. Continuity and Winding Resistance Test
Perform a continuity test to conrm
continuity of all windings. Perform a winding
resistance test and compare the measured
values with factory test data. An increase of
more than 10% may indicate a loose internal
connection.
2. Ratio Test
Using a transformer turns ratio (TTR) tester,
perform a ratio test to verify the proper
primary-to-secondary winding ratio. The
measured value should be within 0.5% of the
voltage ratio indicated on the transformer
nameplate. If the transformer is provided
with high-voltage taps, measure the ratio
at each tap position to verify that each of
the ratios is correct. Follow the instructions
and safety precautions provided by the TTR
equipment manufacturer. For additional
information about ratio testing, refer to IEEE
Standard C57.12.90.
3. Insulation Resistance Test
Perform a 1,000-Volt insulation test (Megger
test) to measure the resistance of the
insulation between windings and from each
winding to ground. Follow the instructions
and safety precautions provided by the test
equipment manufacturer. Prior to the test,
bushings must be thoroughly cleaned with
denatured alcohol to remove any moisture
or contaminants that could inuence the
test results. Insulation resistance should
measure at least 1.0 GΩ.
An insulation resistance test must not
be performed on a wye-wye connected
transformer with an Ho-Xo bushing without
rst disconnecting the internal connection
between the primary and secondary neutrals.
This connection can be found on a terminal
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR SERIOUS
PERSONAL INJURY AND MAY ALSO RESULT IN
DAMAGE TO THE EQUIPMENT.
• Do not energize the transformer using single-
phase switches or fuses. Use only gang-
operated three-phase switches to energize a
three-phase transformer
• Do not energize the transformer if the
primary switch handle is in the “GROUND”
position
• Do not operate the transformer with any of
the primary phases open.
• Only qualied personnel with appropriate
equipment should measure transformer
voltages.
• Wear personal protective equipment to
prevent injury from potential arc-ash or
contact with dangerous voltages.
• Make sure the transformer is properly
grounded at all times.
• Insulated dead-end caps or plugs must be
installed on all unused dead-front high-
voltage bushings. Dust caps must not be
used in place of insulated dead-end caps or
plugs.
• CT leads, if supplied, must be connected
to a metering load or shorted together and
grounded to prevent dangerous voltages at
the CT terminals.
• Do not operate the tap switch while the
transformer is energized from either the
primary or secondary side.
WARNING
SECTION 4: INSPECTION AND TESTING
DANGER
FAILURE TO FOLLOW THE INSTRUCTIONS BELOW
WILL RESULT IN DEATH OR SERIOUS PERSONAL
INJURY AND MAY ALSO RESULT IN DAMAGE TO
THE EQUIPMENT.
Be aware of dangerous voltages and avoid
personal contact with live terminals

Document 2.4.128, Revision 3
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Network Transformer Instruction Manual
board located under oil in the transformer
tank. Refer to “Opening the Transformer
Tank” for instructions.
4. Tap Changer Setting
For transformers supplied with high-voltage
taps, check the tap changer setting to
ensure it is set to the proper position for the
required voltage. The tap changer setting
must not be changed while the transformer
is energized. Unless otherwise specied,
tapped transformers will be shipped from the
factory with the tap switch set to the nominal
position.
5. Series/Multiple and Delta/Wye Switch
Settings
For transformers supplied with a delta/
wye and/or series/multiple switch, check
switch settings to make sure they are set to
the correct position. If delta/wye or series/
multiple connections are made using an
internal terminal board instead of a switch,
check to ensure that these connections are
made properly according to the chart on the
transformer nameplate. Refer to “Opening
the Transformer Tank” for instructions.
Neither the series/multiple nor delta/wye
switch setting should be changed while the
transformer is energized. Unless otherwise
specied, transformers are shipped from the
factory with series/multiple and delta/wye
connections set to the highest voltage.
6. Grounding
Check to ensure that the transformer tank is
permanently and effectively grounded.
7. Bolted Connections
Check all bolted connections for tightness,
referring to nominal torque guidelines
contained in Tables 3 through 6.
8. Fluid Levels
The transformer main tank and primary
switch chamber are shipped from the factory
with insulating uid lled to the proper level,
indicated by the 25°C mark on the uid level
gauge. Before energizing the transformer,
verify proper uid levels by observing the
gauges. Be aware that uid levels vary with
uid temperature. A transformer found to
have a low uid level should be checked for
potential leaks, repaired as necessary and
lled to the proper level with the same type
of liquid as specied on the transformer
nameplate. When wiping sleeve entrances
are provided, the terminal chamber is
shipped dry, unless otherwise specied by
the customer.
9. Fluid Temperature
Before energizing the transformer, observe
the uid temperature gauge and make sure
the temperature is no lower than the values
listed below.
-20°C (-4°F) for conventional
transformer oil and silicone uid
-0°C (32°F) for R-Temp uid
-10°C (14°F) for FR3 uid
10. Current Transformers
If current transformers (CTs) are supplied,
connect CT leads to a metering load. If CT
leads are not connected to a metering load,
they must be shorted together and grounded
before the transformer is energized.
11. Accessory Wiring
Check the wiring of control and alarm
circuits, if supplied, to make sure there are
no loose connections and no damage to wire
insulation.
12. Tank Finish
Check all painted surfaces to make sure that
there is no damage or corrosion.
13. Tools
Check to make sure that all tools and
equipment are accounted for.
14. Internal Inspection
The transformer main tank is sealed and
should not be opened unless necessary. If
the transformer main tank must be opened,
refer to “Opening the Transformer Tank” for
instructions. Contact the Howard Industries
Transformer Division prior to opening the
tank.

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Network Transformer Instruction Manual
Post-Energization Inspection and Tests
After the transformer is energized, the following tests
and inspections should be performed.
1. Verifying Correct Voltage
Before supplying voltage from the transformer
to the load, verify that the secondary voltage
is correct. Using a suitable AC voltmeter,
measure the voltage of the secondary
windings and make sure they agree with the
secondary voltages listed on the transformer
nameplate.
2. Checking for Leaks
Check the main tank, high-voltage switch
chamber and terminal chamber to make sure
there are no uid leaks.
3. Observing Operation
After the transformer is initially energized,
visually inspect it occasionally for a few hours,
to make sure that no abnormal conditions are
observed.
4. Checking Gauges
Observe the uid level and uid temperature
gauges to conrm the proper uid level and
temperature.
5. Audible Sound
It is normal for transformers to emit an
audible humming sound, which is primarily
caused by alternating magnetic ux in the
transformer core. Amplitude and harmonic
content of the sound is inuenced by
transformer size, the energizing voltage level
and sinusoidal purity, load conditions and
acoustic conditions at the installation site.
Refer to NEMA Standards Publication TR-1,
Transformers, Regulators and Reactors, and
IEEE Standard C57.12.90, IEEE Standard
Test Code for Liquid-Immersed Distribution,
Power, and Regulating Transformers, for
more information about design sound levels
and factory sound testing. Unusual sounds
should be investigated, as this might indicate
a potential problem.
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR
SERIOUS PERSONAL INJURY AND MAY ALSO
RESULT IN DAMAGE TO THE EQUIPMENT.
• Do not energize the transformer
using single-phase switches or fuses.
Use only gang-operated three-phase
switches to energize a three-phase
transformer
• Do not operate the transformer with
any of the primary phases open.
• Only qualied personnel with
appropriate equipment should
measure transformer voltages.
• Wear personal protective equipment
to prevent injury from potential arc-
ash or contact with dangerous
voltages.
• Make sure the transformer is securely
and effectively grounded at all times.
• CT leads must be connected to the
metering load or shorted together
and grounded to prevent dangerous
voltages at the CT terminals.
DANGER
FAILURE TO FOLLOW THE INSTRUCTIONS BELOW
WILL RESULT IN DEATH OR SERIOUS PERSONAL
INJURY AND MAY ALSO RESULT IN DAMAGE TO
THE EQUIPMENT.
Be aware of dangerous voltages and avoid
personal contact with live terminals

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Network Transformer Instruction Manual
The following operating instructions and descriptions
of switching and protective devices are intended
to be a general guide for operation of Howard
secondary network transformers in normal
environments. Although efforts have been made
to ensure accuracy and completeness, these
instructions and descriptions do not address every
conceivable application or circumstance that might
be encountered. Personnel should read and comply
with any safety and instructional labels that might
accompany an accessory device.
Some of the accessory devices described below are
optional and may not be supplied on any particular
transformer design. The inclusion of particular
accessory device in any transformer design is
governed by industry standards and by individual
user specications.
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR SERIOUS
PERSONAL INJURY AND MAY ALSO RESULT IN
DAMAGE TO THE EQUIPMENT.
• Do not operate load-break equipment if a
fault condition is suspected.
• Do not operate a no-load tap changer,
series/multiple switch, or delta/wye
switch while a transformer is energized.
• Use a live-line tool (hot stick or shotgun
stick) to operate transformer load-break
equipment.
• After operating transformer loadbreak
equipment, check that voltages at
transformer terminals are the expected
values. Checking voltages veries that
loadbreak equipment operated properly
and that electrical circuit conditions are as
expected.
• Before servicing the transformer,
ALWAYS de-energize the transformer,
and then proceed to ground all primary
and secondary transformer terminals
following industry accepted safe grounding
practices. Place the network protector in
the “OPEN” position. Then operate the
primary disconnect switch, moving the
handle to the “GROUND” position.
• Follow industry accepted safety practices
and utilize personal protective equipment
(PPE) when working with this equipment.
• Do not operate uid-immersed load-break
switching devices when the insulating uid
temperature is below the following limits:
-20°C (-4°F) for conventional
transformer oil and silicone uid
-0°C (32°F) for R-Temp uid
-10°C (14°F) for FR3 uid
WARNING
SECTION 5: OPERATION OF SWITCHING AND PROTECTIVE DEVICES

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Network Transformer Instruction Manual
Tap Changer
The de-energized (no-load) tap changer may be used
to adjust the voltage ratio of a transformer while it
is de-energized. It is intended to allow adjustment
of the output (secondary) voltage to the rated
value. Do not use the tap changer to raise or lower
the output voltage to any voltage other than that
indicated on the transformer nameplate. If the tap
changer is set to provide an output voltage different
from rated voltage, core saturation may result,
producing high excitation current, high core loss and
a high noise level.
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR
SERIOUS PERSONAL INJURY AND MAY ALSO
RESULT IN DAMAGE TO THE EQUIPMENT.
• Do not operate a de-energized tap
changer unless the transformer is
completely de-energized.
• Do not re-energize the transformer unless
the tap changer handle is locked into
position.
The de-energized tap changer is located on the
main tank cover, protected by a 2-inch pipe cap. The
tap changer can be rotated by means of a special
wrench that must be inserted into the operating
mechanism. When the tap changer is not in use, the
protective cap must be installed. Apply a suitable
sealant to the threads of the coupling before
installing the cap.
Never operate a de-energized tap changer while the
transformer is energized. Tap changers normally
have ve or seven tap positions, as indicated on
the tap changer dial plate and on the transformer
nameplate. A locking mechanism is provided to lock
the tap changer into position and prevent accidental
operation. Do not re-energize the transformer until
the tap changer is rmly locked into a tap position.
The wrench is keyed, so that it can be removed only
when the tap changer is properly placed into one of
the tap positions.
Unless otherwise specied, transformers supplied
with tap changers will be shipped from the factory
with the switch set to the nominal position.
Series/Multiple or Delta/Wye Switch
Transformers designed with series/multiple windings
(dual-voltage or triple-voltage) or re-connectable
delta/wye windings are provided with a de-energized
series/multiple or delta/wye switch, as indicated on
the transformer nameplate. The series/multiple or
delta/wye switch is usually located on the main tank
cover, protected by a 2-inch pipe cap. The switch can
be rotated by means of a special wrench that must
be inserted into the operating mechanism. When
the switch is not in use, the protective cap must be
installed. Apply a suitable sealant to the threads of
the coupling before installing the cap.
Never operate a de-energized series/multiple or
delta/wye switch while the transformer is energized.
A locking mechanism is provided to lock the switch
into position and prevent accidental operation. Do
not re-energize the transformer until the switch is
rmly locked into the desired position. The wrench is
keyed, so that it can be removed only when the tap
changer is properly placed into position.
Unless otherwise specied, transformers are shipped
from the factory with series/multiple and delta/wye
connections set to the highest voltage.
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR
SERIOUS PERSONAL INJURY AND MAY ALSO
RESULT IN DAMAGE TO THE EQUIPMENT.
• Do not operate a series/multiple or delta/
wye switch unless the transformer is
totally de-energized.
• Do not re-energize the transformer unless
the series/multiple or delta/wye switch
handle is locked into position.

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Network Transformer Instruction Manual
Primary Disconnect and Grounding Switch
Network transformers are normally supplied with a
three-position primary disconnect switch (sometimes
called a “network switch”), which is housed in a uid-
lled chamber welded to the main tank below the
primary terminal chamber. Primary switches can be
designed as a non-interrupting switch suitable only
for completely de-energized operation, or designed
to interrupt magnetizing current only (Sometimes
called a “mag-break switch.”). An external, pad-
lockable switch operating handle is provided with
a mechanical latching mechanism to prevent
accidental movement of the switch.
Three-position switches are designed with an
operating sequence of OPEN, CLOSED, and
GROUND. In the OPEN position the primary feeder
is disconnected from the transformer and from
ground. In the CLOSED position the primary feeder
is connected to the transformer. In the GROUND
position the primary feeder is solidly grounded, while
the transformer is disconnected and not grounded by
the grounding switch.
Unless otherwise specied, network transformers are
shipped from the factory with the primary disconnect
and grounding switch set to the CLOSED position.
Contact the Howard Industries Transformer Division
to inquire about other switch congurations and
options that may be available.
Three-Position Non-Interrupting Primary Disconnect
and Grounding Switch
The non-interrupting switch is suitable for use only
when the transformer is totally de-energized. An
electrical interlock is normally provided to prevent
operation of the switch while the transformer is
energized from either the high-voltage or low-voltage
side.
Before attempting to operate the non-interrupting
primary switch, verify that the transformer is not
energized from either the high-voltage or low-voltage
side. Use the following procedure to move the switch
from the OPEN to the CLOSED position.
1. Operate the blocking toggle pin.
2. Pull the mechanical locking pin on the handle.
3. Rotate the handle until the mechanical locking
pin engages in the CLOSED position.
Use the following procedure to move the switch from
the CLOSED to the GROUND position.
1. Operate the blocking toggle pin.
2. Pull the mechanical locking pin on the handle.
3. Rotate the handle until the mechanical locking
pin engages in the GROUND position.
Three-Position Mag-Break Primary Disconnect and
Grounding Switch
The mag-break switch is designed to operate when
only magnetizing current is present and is prevented
from operating while the network protector is in
the closed position. The switch is equipped with an
electric interlock system, which permits operation
of the switch according to the parameters listed
in Table 1 below. The interlock system requires
a source of power that is independent of the
associated network transformer and an auxiliary
contact on the network protector. The interlock
system will lock if it looses its independent power
source.
Table 1: Mag-Break Primary Switch Operation
Primary
Feeder
Status
Network
Protector
Position
Switch
Operation
De-energized OPEN Switch may be operated to
any position
De-energized CLOSED Switch cannot be operated
Energized OPEN
Switch may operate be-
tween CLOSED and OPEN
positions. Switch cannot
operate between CLOSED
and GROUND positions.
Energized CLOSED Switch cannot be operated.
FAILURE TO FOLLOW THE INSTRUCTIONS BELOW
COULD RESULT IN DEATH OR SERIOUS PERSONAL
INJURY AND MAY ALSO RESULT IN DAMAGE TO
THE EQUIPMENT.
Although the electrical interlock system should
prevent unsafe operation of the primary switch,
the operator should verify that the transformer is
disconnected from the primary feeder and that
the network protector is in the OPEN position.
WARNING

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17
Network Transformer Instruction Manual
Operation of the three-position mag-break switch is
similar to that of the three-position non-interrupting
switch. Before attempting to operate the mag-break
switch, verify that the network protector is in the
open position.
Sequential Grounding Provisions
When specied, the three-position primary
disconnect and grounding switch can be supplied
with two additional positions to allow for sequential
grounding of the primary feeders. Typical switch
operation is described in Table 2 below; however,
other user-specied switch characteristics are
available. Markings on the switch handle indicate
switch position. The switch may be operated in either
a clockwise or counterclockwise direction.
Table 2: Sequential Grounding Switch Operation
Switch
Position
Primary Feeder Connections
A Phase B Phase C Phase
A Grounded Open Open
AB Grounded Grounded Open
GROUND Grounded Grounded Grounded
OPEN Open Open Open
CLOSED Closed Closed Closed
Phase Sequence Identication Provisions
Optional phase sequence identication provisions
(also known as “phasing tubes”) are provided
when specied to allow determination of the phase
sequence of incoming primary feeders. Phasing
tubes are located on the switch chamber cover and
are positioned to allow phasing probes to be inserted
and make electrical contact with live portions of the
switch bushings. Pipe plugs or caps are provided to
seal phasing tubes when not in use.
Network Protector
Howard network transformers are usually supplied
with network protector mounting provisions designed
according to user specications. These provisions
typically consist of a secondary throat with mounting
holes, guide pins and gasket. A steel shipping guard
is installed over the secondary throat to protect the
secondary bushings, connectors and throat ange
from damage during shipment and storage.
The network protector should be installed, operated
and maintained by the user according to the
instructions provided by the network protector
manufacturer.
Other Switching and Protective Devices
Contact the Howard Industries Transformer Division
for information related to any other switching
or protection options not discussed in these
instructions.
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR SERIOUS
PERSONAL INJURY AND MAY ALSO RESULT IN
DAMAGE TO THE EQUIPMENT.
Although the electrical interlock system should
prevent unsafe operation of the primary
switch, the operator should verify that the
transformer is disconnected from the primary
feeder and that the network protector is in the
open position.

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Network Transformer Instruction Manual
Some of the accessory devices described below are
optional and may not be present in any particular
transformer design. The inclusion of particular
accessory device in any transformer design is
governed by industry standards and by individual
user specications.
Diagrammatic Nameplate
The transformer nameplate is supplied on each
transformer and provides a circuit diagram and
certain physical and electrical information in
accordance with IEEE Standard C57.12.00.
Fluid Level Gauge
Fluid level gauges are magnetic dial-type devices
that indicate internal uid levels. One gauge is
welded to the transformer main tank above the
primary terminal chamber at the 25°C uid level. A
second gauge is welded on the side of the primary
switch chamber at the 25°C uid level.
If a gauge reads “LOW,” the cause of the low reading
should be investigated and corrected. A low uid
level in the main tank could cause overheating of the
transformer and could compromise the insulation
system. A low uid level in the primary switch
chamber could compromise the insulation system of
the primary switch.
Fluid level gauges can be supplied with optional
switch contacts, which can be used to provide a
remote indication of low uid level.
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH
OR SERIOUS PERSONAL INJURY AND
MAY ALSO RESULT IN DAMAGE TO THE
EQUIPMENT.
• Do not energize the transformer if the
uid level is low.
• Maintain proper uid level while the
transformer is energized.
Fluid Temperature Gauge
The uid temperature gauge is a dial-type bi-metal
device that indicates the uid temperature at
the top of the uid column in the main tank. The
temperature gauge is mounted above the primary
terminal chamber in a dry leak-proof well, permitting
removal of the gauge without exposure to the tank
uid.
The gauge is furnished with a red drag-hand pointer
that indicates the maximum temperature measured.
The drag-hand can be reset by rotating the magnet
at the center of the dial or, on some types, by
pressing a reset button. Fluid temperature gauges
may also be supplied with switch contacts, which can
be used to provide a remote indication of low or high
temperature.
During normal operation the uid temperature
gauge should read less than the sum of the ambient
temperature and the rated temperature rise
(normally 85°C). Refer to IEEE Standard C57.91 for
loading recommendations.
Filler Plug and Upper Filter Press Connection
The ller plug and upper lter press connection is
located on the main tank cover, consisting of 1-inch
NPT opening with protective plug.
Combination Drain and Bottom Filter Valve
The combination drain and bottom lter valve is
provided to permit draining, ltering and sampling of
the insulating uid for testing purposes. Two valves
are typically provided, one located on the main
transformer tank and another on the primary switch
chamber. Refer to “Sampling and Testing the Fluid,”
“Removing or Lowering the Fluid,” and “Filling with
Fluid” for instructions.
Terminal Chamber Vent and Level Plug
The terminal chamber vent and level plug is located
on the terminal chamber cover at the 25°C uid
(or compound) level, which can be used to vent the
chamber and check the uid (or compound) level.
SECTION 6: ACCESSORIES

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Network Transformer Instruction Manual
Air Test Provision
The air test provision is located on the primary switch
chamber above the 85°C uid level. The provision
consists of a 0.5-inch NPT opening with protective
plug, which can be used for testing the air inside the
switch chamber.
Automatic Pressure Relief Valve and Pressure Relief
Device
The automatic pressure relief valve (PRV) is designed
to relieve excessive tank pressures that might occur
during operation of the transformer. The standard
subway-type PRV consists of a self-resealing, spring-
loaded diaphragm and is normally located above the
uid level on the side of the transformer main tank.
The PRV can be operated manually by pulling on the
pull-ring with a live-line tool. An optional high ow-
rate pressure relief device (PRD) is supplied when
specied, and mounted on the transformer main
tank cover. The high ow-rate PRD can be supplied
with optional switch contacts, which can be used to
provide a remote indication of valve activation.
When gas pressure in the tank exceeds the PRV’s or
PRD’s specied limit, the gas pressure will cause the
valve to open, venting the excess pressure. After the
internal pressure decreases below the PRV or PRD
reseal rating, the valve will automatically close and
reseal the transformer.
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR
SERIOUS PERSONAL INJURY AND MAY ALSO
RESULT IN DAMAGE TO THE EQUIPMENT.
• The cause of PRV or PRD activation should
always be investigated, since pressure
venting indicates a potential problem
inside the transformer.
• Personnel should wear eye and skin
protective equipment when using the PRV
to relieve tank pressure. Hot uid may be
expelled.
• Do not attempt to disassemble a PRD.
Internal components may be under high
spring pressure, creating a potential
hazard from ying objects.
Primary Entrance
The primary entrance is located on the top of the
terminal chamber and is provided for connection to
the primary feeders. The primary entrance typically
consists of separable insulated connectors, wiping
sleeves or potheads, as specied by the user.
When separable insulated connectors are provided,
they may consist of universal bushing wells only,
universal busing wells with factory-installed bushing
inserts, or one-piece bushings. In the case of
separable insulated connectors, a single chamber is
provided to house the terminals and primary switch,
unless a separate terminal chamber is specied
by the user. When a separate terminal chamber is
provided, it is lled with uid at the factory and need
not be opened in the eld. Installation of bushing
inserts and primary feeder cables should be carried
out in accordance with instructions provided by the
bushing manufacturer.
When wiping sleeves or potheads are provided,
primary feeder connections will be made inside the
terminal chamber. In this case, terminal chambers
are shipped dry, and must be lled with the proper
insulating uid or compound after connections are
made and the chamber cover has been properly
installed. Refer to the cable manufacturer’s
instructions for proper method of cable connection,
use of stress cones and selection of insulating uid
or compound. When lling with compound, voids
must be prevented, otherwise partial discharge
issues and cable failure could result. Consult
compound manufacturer for recommended lling
temperature and technique.
High-Voltage Bushings
Externally-removable high-voltage bushings are
installed between the main tank and the primary
switch chamber. These bushings can be removed
and replaced through the switch chamber. When
replacing bushings, new gaskets should be used.
When a separate terminal chamber is provided,
externally-removable bushings are also installed
between the primary switch chamber and the
terminal chamber. These bushings can be removed
and replaced from the terminal chamber. When
replacing these bushings, new gaskets should be
used.

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Network Transformer Instruction Manual
Secondary Bushings
Three externally-removable secondary bushings are
bolted to the main tank wall inside the secondary
throat. Each is tted with a exible connector for
connection to a network protector. The low-voltage
neutral connection consists of a blade welded to the
main tank or, when specied by the user, a fully-
insulated bushing.
Current Transformers
Optional current transformers (CT’s) are supplied
when specied, to allow remote measurement of
secondary phase currents. When provided, CT’s
are mounted inside the main tank, immersed in
insulating uid. CT leads are brought out to an
external junction box mounted on the main tank.
Transformers are shipped from the factory with CT
leads shorted together and grounded. If the CT’s
are not connected to a metering load by the user,
they must remain shorted and grounded to avoid
hazardous voltage at the CT secondary terminations.
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR
SERIOUS PERSONAL INJURY AND MAY ALSO
RESULT IN DAMAGE TO THE EQUIPMENT.
CT leads must be connected to a load or
short-circuited and grounded before the
transformer is energized to avoid hazardous
voltage at the CT terminals.
Other Accessory Devices
Network transformers may be supplied with
accessory devices not discussed in these
instructions. In such cases, contact the Howard
Industries Transformer Division for information.