Howard Industries HI-105 Instructions Manual
Three-Phase Padmounted Distribution Transformers
Document 2.4.126, Revision 4
October 2017
Instructions (HI-105)
Installation, Operation, and Maintenance
of Three-Phase Padmounted Distribution Transformers
45 kVA through 10,000 kVA
Howard Industries
Distribution Transformer Division
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Document 2.4.126, Revision 4
October 2017
READ THIS IMPORTANT SAFETY INFORMATION
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 damage to the equipment.
WARNING indicates a potentially hazardous situation which, if not avoided, may
result in death or serious personal injury, and/or damage to the equipment.
Three-Phase Padmounted Distribution Transformers
CAUTION indicates a potentially hazardous situation which, if not avoided, may
result in minor or moderate personal injury, and/or damage to the equipment.
No one should attempt to service or perform maintenance activities on the
equipment until it has been effectively de-energized, and all high-voltage and low-
voltage bushing terminals have been properly grounded. Only qualied personnel
should install, maintain, and operate this equipment. Qualied personnel are
those who are trained in the installation, maintenance, and operation of highvoltage 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 dened in IEEE Standard C57.12.00. Features
presented herein may not be present in all equipment designs. Standard and
optional features are subject to change without notice.
Although efforts have been made to ensure accuracy and completeness, these
instructions do not address every conceivable application or circumstance that
might be encountered. Howard Industries makes no representation or warranty
with respect to, and assumes no responsibility for the completeness, accuracy,
sufciency, or usefulness of, these instructions.
Questions regarding installation, operation, and maintenance of the equipment,
particularly when encountering unusual or special circumstances that may not
be sufciently covered by these instructions, should be directed to the Howard
Industries Transformer Division.
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Three-Phase Padmounted Distribution Transformers
Document 2.4.126, Revision 4
October 2017
TABLE OF CONTENTS
Important Safety Information........................................................................................................................2
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Section 1: Introduction.................................................................................................................................5
Section 2: Receiving, Handling and Storage..............................................................................................….6
Drawings and Documents.........................................................................................................….....6
Lifting and Handling....................................................................................................................…..6
Initial Inspection...........................................................................................................................….6
Fluid Level....................................................................................................................................….7
Internal Inspection.........................................................................................................................….7
Fluid Sampling..................................................................................................................................7
Transformer Storage.....................................................................................................................….8
Section 3: Installation..................................................................................................................................9
Lifting and Handling.........................................................................................................................9
Jacking, Skidding and Rolling............................................................................................................9
Location and Mounting.................................................................................................................….9
Verifying Enclosure Integrity............................................................................................................10
Grounding.......................................................................................................................................10
High-Voltage and Low-Voltage Connections.......................................................................................10
High-Voltage Connections..............................................................................................................10
Low-Voltage Connections...............................................................................................................11
Section 4: Inspection and Testing Before and After Initial Energization.........................................................12
Pre-Energization Inspection and Tests..........................................................................................…12
Ratio Test......................................................................................................................................12
Insulation Resistance Test.............................................................................................................12
Tap Changer Setting…………………………………………………………….........................................................12
Series/Multiple or Delta/Wye Switch Settings…………………………………................................................13
Grounding………………………………………………………………………............................................................….13
Bolted Connections……………………………………………………………...................................................….....13
Fluid Level………………………………………………………………………......................................................….....13
Fluid Temperature………………………………………………………………....................................................…...13
Internal Fault Detector...............................................................................................................…..13
Current Transformers…………………………………………………………....................................................…....13
Accessory Wiring……………………………………………………………….....................................................…....13
Tank Finish……………………………………………………………………...........................…............................….....13
Tools……………………………………………………………………………..........................................................…....13
Internal Inspection………………………………………………………………....................................................…..13
Post-Energization Inspection and Tests……………………………………...............................................….....14
Verifying Correct Voltage...........................................................................................................…...14
Checking for Leaks……………………………………………………………...................................................…......14
Observing Operation..............................................................................................................…......14
Checking Gauges………………………………………………………………..................................................…..14
Audible Sound…………………………………………………………………......................................................…....14
Locking the Terminal Compartment…………………………………………….........................................….......14
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Section 5: Operation of Switching and Protective Devices………………................................................................15
Tap Changer……………………………………………………………………...................................................................15
Series/Multiple or Delta/Wye Switch………………………………………….........................................................16
Load-Break Switch…………………………………………………………..................................................................…16
Fuses………………………………………………………………………..................................................................…......16
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October 2017
Three-Phase Padmounted Distribution Transformers
Internal Weak-Link Cartridge Fuse……………………………………………..........................................................17
Bay-O-Net Fuse………………………………………………………………….................................................................17
Dead-Break Dry-Well Canister Fuse……………………………………………........................................................18
Internal Partial-Range Current-Limiting Fuse………………………………….....................................................19
S&C Arc-Strangler………………………………………………………………................................................................19
S&C Fused Switch………………………………………………………………...............................................................19
Vacuum Fault Interrupter……………………………………………………….............................................................19
Surge Arresters………………………………………………………………....................................................................20
Internal MOV Surge Arresters…………………………………………….........................................................…..….20
Molded-Case Circuit Breakers………………………………………………...........................................................…21
Hot-Stick Operable Devices……………………………………………………........................................................... 21
Other Switching and Fusing Devices…………………………………………..........................................................21
Section 6: Operation of Bushings, Gauges and Accessory Devices......................................................................22
Pressure-Vacuum Gauge……………………………………………………….............................................................22
Fluid Level Gauge and Sight Plug ……………………………….........................................................................22
Fluid Temperature Gauge………………………………………………………............................................................22
Drain Valve and Sampling Device……………………………………………...........................................................22
Automatic Pressure Relief Device………………………………………………........................................................23
Internal Fault Detector…………………………………………………………..............................................................23
High-Voltage Bushings…………………………………………………………..............................................................23
Low-Voltage Bushings……………………………………………………………............................................................24
Current Transformers…………………………………………………………….............................................................24
Accessor y Brackets…………………………………………………………….................................................................24
Flip-Top Terminal Compartment Cover…………………………………................................................................24
Door Handle, Padlock and Security Bolt……………………………………..........................................................24
Lift-Off Door Hinges……………………………………………………………................................................................24
Other Accessory Devices………………………………………………………..............................................................24
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Section 7: Maintenance...........................................................................................................................................25
Periodic Inspection………………………………………………………………..............................................................25
Inspection Checklist………………………………………………………………............................................................26
Electrical Tests……………………………………………………………………...............................................................27
Exterior Paint Finish……………………………………………………………...............................................................28
Fluid Leaks………………………………………………………………………..................................................................28
Audible Sound Level……………………………………………………………...............................................................28
Molded-Case Circuit Breakers…………………………………………………...........................................................29
Other Accessory Devices………………………………………………………..............................................................29
Sampling and Testing the Fluid………………………………………………….........................................................29
Filtering the Fluid…………………………………………………………………..............................................................29
Removing or Lowering the Fluid………………………………………………...........................................................29
Filling with Fluid………………………………………………………………...................................................................29
Opening the Transformer Tank…………………………………………………..........................................................30
Torque Guidelines………………………………………………………………................................................................31
Table 1—Torque Guidelines for External Cabinet Fasteners………………...................................................31
Table 2—Torque Guidelines for External Bushing Mounting Hardware……..............................................31
Table 3—Torque Guidelines for External Bushing Terminal Connections….............................................32
Table 4—Torque Guidelines for Accessories………………………………..........................................................32
Additional Maintenance Instructions……………………………………...........................................................….33
Repair Parts………………………………………………………….....................................................................……….33
Warranty Claims……………………………………………………....................................................................……….
Transformer Disposal.……………………………………………....................................................................………
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Three-Phase Padmounted Distribution Transformers
SECTION 1: INTRODUCTION
This document is intended as a general guide for
the installation, operation and maintenance of
Howard Industries three-phase compartmental
padmounted distribution 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.
The instructions contained herein are applicable
to transformers operated in normal conditions
as specied 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 sufciently covered by these
instructions) should be directed to the Howard
Industries Transformer Division.
Document 2.4.126, Revision 4
October 2017
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.
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Document 2.4.126, Revision 4
October 2017
SECTION 2: RECEIVING, HANDLING AND STORAGE
Three-Phase Padmounted Distribution Transformers
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
warning labels, and provides physical dimensions
and weights. The nameplate provides electrical
characteristics, winding connections, and weights.
The wiring diagram provides details of any control,
fan and alarm wiring that may have been supplied.
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.
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW MAY CAUSE DEATH OR SERIOUS
PERSONAL INJURY AND/OR 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.
Transformers should be lifted in an upright position,
allowing the transformer to tilt no more than 15°
from vertical. Lifting cables should be no more
than 20° from vertical. It is recommended that
a spreader bar be used to keep the lifting cables
nearly vertical to enable a safe lift and to reduce
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, a thorough receiving inspection should
be conducted to detect any damage or loss that
might have occurred during 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 shipping documents. Also,
check the nameplate for kVA rating, high-voltage
rating, low-voltage rating, impedance and other
design characteristics, and make sure they
comply with the specications.
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 unqualied acceptance and
a waiver of all such claims by the purchaser.
3. The tank vacuum/pressure gauge may
indicate a positive or negative reading when
the transformer is received, depending on the
relative temperatures of the uid and ambient
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Three-Phase Padmounted Distribution Transformers
Document 2.4.126, Revision 4
October 2017
air. A rising or falling reading that varies over
time with ambient temperature indicates that
the transformer tank is sealed effectively. If the
vacuum/pressure gauge shows a constant zero
reading, this indicates the possibility of a tank leak.
If this occurs, the tank should be checked carefully
for leaks as indicated in the following step.
4. Check the tank for indication of uid leaks,
looking carefully at weld seams, bushings,
gauges, valves and all other tank 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.
5. Check for external damage including dents
or scratches on the tank walls, radiators and
terminal compartment. 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.
extremely hot. When checking the uid level, bear
in mind that the level will vary as a function of uid
temperature.
A transformer found to have a low uid level should
be checked for potential leaks and lled to the
proper level with the same type of liquid as that
specied on the transformer nameplate.
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW MAY CAUSE DEATH OR SERIOUS
PERSONAL INJURY AND/OR DAMAGE TO
THE EQUIPMENT.
• Do not energize the transformer if the
uid level is low.
• Maintain proper uid level at all times
while the transformer is energized.
• Exercise caution when checking the uid
level with the uid level plug, as the uid
may spill and may be extremely hot.
6. Check for broken, cracked, or damaged
bushings, gauges, valves and other ttings and
accessories.
7. Check for missing or damaged component parts
and packages that shipped separately from the
transformer.
Fluid Level
The transformer is shipped from the factory with
dielectric uid lled to the proper level. Before
energizing the transformer, verify proper uid level
by observing the uid level gauge. The uid level
gauge pointer should be between the “High” and
“Low” marks. For transformers supplied with a uid
sight plug, the uid level can be directly observed
if it is within acceptable range. If the transformer
does not have a uid level gauge or sight plug, the
uid level can be checked by removing the liquid
level plug located at the 25° C mark. Exercise
caution when checking the uid level using the uid
level plug, as the uid may spill out and may be
Internal Inspection
An internal inspection of the transformer tank is
rarely necessary and is recommended only when
there are obvious indications that the transformer
has received severe impact damage during transit
or when necessary to perform recommended preenergization tests or inspections. Do not open the
transformer tank without authorization from the
Howard Industries Transformer Division.
If the transformer 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 indication that moisture or other
contaminants have accidently entered the tank
during transit. If moisture or contaminates in the
uid is suspected, contact the Howard Industries
Transformer Division immediately for instructions.
If uid sampling is required, refer to “Sampling the
Fluid” for instructions.
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Document 2.4.126, Revision 4
October 2017
Transformer Storage
Transformers may 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
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 tank.
Three-Phase Padmounted Distribution Transformers
It is recommended that the transformer be
inspected periodically while it is in extended
storage. Ensure that an effective pressure seal
is maintained, and check for leaks and corrosion.
Any damage or defects should be repaired
immediately.
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Three-Phase Padmounted Distribution Transformers
SECTION 3: INSTALLATION
Document 2.4.126, Revision 4
October 2017
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.
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° from vertical. It is recommended
that a spreader bar be used to keep the lifting
cables nearly vertical to enable a safe lift and
to reduce 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 MAY CAUSE DEATH OR SERIOUS
PERSONAL INJURY AND/OR 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, Skidding, and Rolling
The transformer tank base is designed for jacking,
skidding and rolling. Do not use radiator ns,
bushings, valves, pipe ttings, 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. When rolling, use an adequate
number of rollers to distribute the transformer
weight evenly. 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
specied 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 specically
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 sufcient strength to
support the weight of the completely assembled
transformer. The transformer should sit ush with
the surface of the pad, so that there are no gaps
that might compromise tamper resistance of the
terminal compartment. The installed transformer
should not tilt in any direction more than three
degrees. Greater tilt may compromise insulation
uid coverage of live parts within the tank and may
prevent insulating uid from circulating properly
through the cooling radiators. Improper circulation
of insulating uid may cause overheating and
reduced transformer life.
The transformer should be located at least 24
inches (710 mm) from any obstruction and
have adequate clearance to allow the terminal
compartment doors to open fully. When installing
transformers designed for indoor operation,
adequate air inlets and outlets must be provided at
the mounting location for proper cooling.
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Document 2.4.126, Revision 4
October 2017
Avoid locating the transformer in corrosive areas.
Remove any shipping braces and packing material
that may have been installed at the factory.
Verifying Enclosure Integrity
Three-phase compartmental padmounted
transformers are designed and constructed to be
tamper resistant according to the requirements
of IEEE Standard C57.12.28 or C57.12.29, as
applicable, and therefore need not be located
in a restricted area. Do not modify the tank or
terminal compartment in such a way that it will
compromise tamper resistance. If for any reason
modications must be made to the tank or terminal
compartment that compromise tamper resistance,
the transformer must then be located in a restricted
area. Such modications of may void the warranty.
Consult with the Howard Industries Transformer
Division before making any modications to the
transformer.
Three-Phase Padmounted Distribution Transformers
DANGER
The transformer must be properly grounded
at all times. FAILURE TO FOLLOW THIS
INSTRUCTION WILL RESULT IN DEATH OR
SERIOUS PERSONAL INJURY, AND DAMAGE
TO THE EQUIPMENT.
High-Voltage and Low-Voltage Connections
Before making high-voltage and low-voltage line
connections, check to make sure that all mating
connector surfaces are clean and smooth.
Connections must be tightened appropriately to
prevent overheating and possible failure of the
connection. Refer to the nominal torque guidelines
contained in Table 3. Connections should be made
with care to avoid placing undue stress on the
bushings.
DANGER
Do not make any modications to the
transformer that might compromise its
tamper resistant construction. FAILURE TO
FOLLOW THIS INSTRUCTION WILL RESULT IN
DEATH OR SERIOUS PERSONAL INJURY, AND
DAMAGE TO THE EQUIPMENT.
Grounding
The transformer must be permanently grounded
according to applicable local and national codes.
Ground the transformer by using ground pads or
nuts located at the base of the front panel in the
terminal compartment. Do not use hold-down
bolts, pipe connections or any other ttings for
ground connections. A proper low-resistance ground
connection is necessary for safe operation.
Transformers with a grounded wye high-voltage
winding and a wye low-voltage 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.
High-Voltage Connections
Three-phase padmounted transformers with
live-front construction are usually supplied with
externally-clamped porcelain high-voltage bushings
for connection to the high-voltage source. Bushings
are supplied with tin-plated eye-bolt or spade
terminals that are suitable for connection to both
aluminum and copper conductors.
Three-phase padmounted transformers with deadfront construction are supplied with universal
bushing wells, one-piece (integral) bushings or
universal bushing wells with 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 compatible with the universal bushing
well. Do not use incompatible or improperly
rated inserts, or equipment damage might occur.
When installing inserts, follow the manufacturer’s
instructions accompanying the insert.
On transformers with dead-front construction,
grounding caps must be installed on all unused
high-voltage bushings before energizing.
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Three-Phase Padmounted Distribution Transformers
Low-Voltage Connections
Three-phase padmounted transformers are
normally supplied with externally-clamped molded
low-voltage bushings, with or without spade
terminals.
Document 2.4.126, Revision 4
October 2017
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