Howard HI-104 User Manual

Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers

Document 2.4.96, Revision 0

March, 2013

Instructions (HI-104)

Installation, Operation, and Maintenance of Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers

Howard Industries

Distribution Transformer Division

Document 2.4.96, Revision 0 March, 2013

! READ THIS IMPORTANT SAFETY INFORMATION

▲

READ THIS ENTIRE INSTRUCTION MANUAL CAREFULLY AND BECOME FAMILIAR WITH THE EQUIPMENT AND ALL SAFETY-RELATED INFORMATION BEFORE PROCEEDING WITH INSTALLATION, OPERATION, OR MAINTENANCE ACTIVITIES.

Safe use of this equipment is dependent on proper installation, operation, and maintenance procedures. Follow all applicable local and national codes.

Do not 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 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 (PPE) and trained in appropriate rst aid procedures. Refer to NFPA 70E.

Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers

Do not rely solely on fuse removal or switch position as conclusive indication that a transformer is de-energized. Be absolutely certain that a transformer is de-energized by checking for zero voltage on all terminals.

Certain information in this manual is marked with the words DANGER, WARNING, or CAUTION, which indicate hazards as listed below.

DANGER indicates an imminently hazardous situation which, if not avoided, will result in death

or serious personal injury, and could 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 could also result in damage to the equipment.

CAUTION indicates a potentially hazardous situation which, if not avoided, could result in minor

or moderate personal injury, and could also result in damage to the equipment.

These instructions are intended as a general guide for the installation, operation and maintenance of the equipment, when operated in “Usual Service Conditions” as dened in IEEE Standard C57.12.00.

Although every effort has 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, sufciency, or usefulness of, these instructions. Features presented herein may not be present in all equipment designs. Standard and optional features are subject to change without notice.

Questions regarding installation, operation, and maintenance of the equipment, particularly when encountering unusual or special circumstances which may not be sufciently covered by these instructions, should be directed to the Howard Industries Transformer Division.

Document 2.4.96, Revision 0

Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers

March, 2013

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 Level .................................................................................................................................................................. 7

Internal Inspection ................................................................................................................................................... 8

Fluid Sampling ........................................................................................................................................................... 8

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 Terminals ........................................................................................................................................... 10

Low-Voltage Terminals ............................................................................................................................................ 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

Multiple-Voltage Switch Setting ..............................................................................................................................12

Grounding ................................................................................................................................................................ 12

Bolted Connections. ................................................................................................................................................ 12

Fluid Level ................................................................................................................................................................ 12

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 ................................................................................................................. 13

Verifying Correct Voltage ......................................................................................................................................... 13

Checking for Leaks. ................................................................................................................................................. 14

Observing Operation ............................................................................................................................................... 14

Checking Gauges .................................................................................................................................................... 14

Audible Sound ......................................................................................................................................................... 14

Locking the Terminal Compartment ...................................................................................................................... 14

SECTION 5: OPERATION OF SWITCHING AND PROTECTIVE DEVICES ...................................................................15

Hot-Stick Operable Devices .................................................................................................................................... 16

Tap Changer ............................................................................................................................................................ 16

Multiple-Voltage Switch .......................................................................................................................................... 16

Load-Break Switch .................................................................................................................................................. 16

Fuses ..........................................................................................................................................................................................17

Document 2.4.96, Revision 0 March, 2013

Internal Weak-Link Fuse ............................................................................................................................................................17

Bay-O-Net Fuse .......................................................................................................................................................................... 18

Dead-Break Dry-Well Canister Fuse ..........................................................................................................................................19

Internal Partial-Range Current-Limiting Fuse .......................................................................................................................... 20

S&C Arc-Strangler ...................................................................................................................................................................... 20

S&C Fused Switch ..................................................................................................................................................................... 20

Surge Arrester ........................................................................................................................................................................... 20

Internal MOV Surge Arrester ..................................................................................................................................................... 20

Low-Voltage Circuit Breaker...................................................................................................................................................... 22

Magnex Interrupter ................................................................................................................................................................... 22

Other Switching and Fusing Devices ........................................................................................................................................ 23

SECTION 6: OPERATION OF TERMINAL COMPARTMENT, BUSHINGS, GAUGES AND ACCESSORY DEVICES ..................... 24

Hot-Stick Operable Devices .......................................................................................................................................................24

Pressure-Vacuum Gauge ...........................................................................................................................................................24

Fluid Level Gauge and Sight Plug .............................................................................................................................................24

Fluid Temperature Gauge .........................................................................................................................................................24

Drain Valve and Sampling Device .............................................................................................................................................24

Automatic Pressure Relief Valve ............................................................................................................................................. 25

Internal Fault Detector ............................................................................................................................................................. 25

High-Voltage Bushings ............................................................................................................................................................. 25

Low-Voltage Bushings .............................................................................................................................................................. 26

Current Transformers ................................................................................................................................................................ 26

Accessory Brackets ................................................................................................................................................................... 26

Terminal Compartment ............................................................................................................................................................. 26

Single-Door Terminal Compartment ........................................................................................................................................ 26

Double-Door Terminal Compartment ........................................................................................................................................27

Other Accessory Devices ...........................................................................................................................................................27

Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers

SECTION 7: MAINTENANCE AND REPAIR .....................................................................................................................................28

Periodic Inspection.................................................................................................................................................................... 28

Inspection Checklist .................................................................................................................................................................. 28

Electrical Tests .......................................................................................................................................................................... 29

Exterior Paint Finish .................................................................................................................................................................. 30

Fluid Leaks ................................................................................................................................................................................ 30

Audible Sound Level.................................................................................................................................................................. 30

Low-Voltage Circuit Breaker.......................................................................................................................................................31

Magnex Interrupter ....................................................................................................................................................................31

Other Accessory Devices ...........................................................................................................................................................31

Sampling and Testing the Fluid ................................................................................................................................................31

Filtering the Fluid .......................................................................................................................................................................31

Removing or Lowering the Fluid ................................................................................................................................................31

Filling with Fluid .........................................................................................................................................................................31

Opening the Transformer Tank ................................................................................................................................................ 32

Torque Guidelines ..................................................................................................................................................................... 33

Additional Maintenance Instructions ...................................................................................................................................... 34

Repair Parts .............................................................................................................................................................................. 34

Warranty Claims ....................................................................................................................................................................... 34

Tables

Table 1: Torque Guidelines for External Cabinet Fasteners .................................................................................33

Table 2: Torque Guidelines for External Bushing Mounting Hardware ................................................................ 33

Table 3: Torque Guidelines for External Bushing Terminal Connections ............................................................. 33

Table 4: Torque Guidelines for Accessories ........................................................................................................... 34

Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers

SECTION 1: INTRODUCTION

Document 2.4.96, Revision 0

March, 2013

This document is intended as a general guide for the installation, operation and maintenance of Howard Industries uid-lled, single-phase, pad-mounted compartmental-type distribution transformers. Although every effort has 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.

These instructions are applicable to single-phase, pad-mounted compartmental-type distribution transformers (including IEEE Type 1, IEEE Type 2 and other styles covered by IEEE Standards C57.12.25 and C57.12.38, and the Space-Saver™ style), which are designed as a single-door style with a one-piece ip-top hood, or the double-door style (sometimes called a “wardrobe-style” transformer), which is designed with two hinged access doors.

All transformer styles are designed for mounting outdoors on a concrete pad or other suitable surface. High-voltage and low-voltage cables enter the transformer terminal compartment from below ground through an opening in the mounting pad.

The instructions contained herein are applicable to transformers operated in usual 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 AND WARNINGS DISPLAYED THROUGHOUT THESE INSTRUCTIONS BEFORE ATTEMPTING ANY INSTALLATION, OPERATION, OR MAINTENANCE ACTIVITIES.

Document 2.4.96, Revision 0 March, 2013

SECTION 2: RECEIVING, HANDLING, AND STORAGE

Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers

Drawings and Documents

Locate all shipping papers, packing lists, specications, and other pertinent information for use during inspection. Verify that the transformer is supplied with a nameplate, required warning labels, and terminal designation markings. Verify that the terminal designation markings are consistent with those on the nameplate. The transformer nameplate provides electrical characteristics, winding connections, and weights. The transformer wiring diagram provides details of any control, fan and alarm wiring that may have been provided.

Lifting and Handling

Lifting lugs or bosses are provided to lift the completely assembled transformer. All lifting lugs or bosses must be used simultaneously to provide a safe, balanced lift. The transformer must not be lifted from any points other than the provided lifting lugs or bosses. Do not use holes in the lifting hooks for lifting. These holes are for tie-down purposes only and are not suitable for lifting. Refer to the transformer nameplate to determine the total weight of the assembled transformer.

Lifting bosses, when provided, consist of 5/8”-11 threaded inserts. Lifting should be accomplished with user-installed 5/8”-11 lifting bolts that have been fully engaged into the threaded bosses and hoist rings. Do not lift with lifting bolts alone. Lifting bolts and hoist rings must be rated to safely support the weight of the completely assembled transformer. A spreader bar should be used to keep the lifting cables or straps nearly vertical, enabling a safe lift and reducing the likelihood of tank deformation or damage to painted surfaces. Transformers should be lifted in an upright position, allowing the transformer to tilt no more than 15 degrees from vertical. Lifting cables or straps should be no more than 20 degrees from vertical.

extend completely through the shipping pallet or runners. Transformers should be lifted with the tank (core/coil and uid compartment) oriented toward the forklift truck, so that the transformer center of gravity is adequately supported. Lifting transformers from the terminal compartment side is not safe, as the transformer may tip and fall.

Lifting double-door style transformers with a forklift truck is not recommended, since weight and balance can be problematic, and radiator panels can be easily damaged.

Transformers should be handled with special care 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 COULD ALSO RESULT IN DAMAGE TO THE EQUIPMENT.

• Lifting equipment, including forklift trucks, cranes, hoists, cables, straps, lifting bolts, hoist rings and spreader bars, must be of adequate capacity to safely lift the completely assembled transformer.

• Keep unnecessary personnel clear while unloading and moving the transformer.

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 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.

Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers

Document 2.4.96, Revision 0

March, 2013

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, lowvoltage 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.

3. The tank vacuum/pressure gauge, when provided, may indicate a positive or negative reading when the transformer is received, depending on the relative temperatures of the uid and ambient 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 and Repair” 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.

6. Check for broken, cracked, or damaged bushings, gauges, valves and other ttings and accessories.

7. Check for missing or damaged component parts and for packages that shipped separately from the transformer.

Fluid Level

The transformer is shipped from the factory with insulating uid lled to the proper level. Before energizing the transformer, verify proper uid level by observing the uid level gauge, if provided. The uid level gauge pointer should be between the “High” and “Low” marks. For transformers provided 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. Prior to removing the ll plug, relieve tank pressure by operating the PRV, being careful to avoid any hot uid that might be expelled from the valve. Exercise caution when checking the uid level using the uid level plug, as the uid may spill out and may be extremely hot. When reinstalling the ll plug, apply a suitable sealing compound to the threads to ensure a proper seal. When checking the uid level, be aware 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 specied on the transformer nameplate. Refer to

“Filling with Fluid.”

Document 2.4.96, Revision 0 March, 2013

! WARNING

▲

FAILURE TO FOLLOW THE INSTRUCTIONS BELOW COULD RESULT IN DEATH OR SERIOUS PERSONAL INJURY, AND COULD ALSO RESULT

IN 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.

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.

Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers

Transformers should be stored on a rm level surface. They may also be stored in racks designed for that purpose. Transformers should not be stacked directly on top of one another, as this may damage the paint nish and cause cabinet misalignment.

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.

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 contaminants 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.

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.

Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers

SECTION 3: INSTALLATION

Lifting and Handling

Single-door style transformers may also be lifted with a forklift truck of adequate lifting capacity to safely handle the weight of the completely assembled transformer. Forks should be of sufcient length to extend completely through the shipping pallet or runners. Transformers should be lifted with the tank (core/coil and uid compartment) oriented toward the forklift truck, so that the transformer center of gravity is adequately supported. Lifting transformers from the terminal compartment side is not safe, as the transformer may tip and fall.

Lifting double-door style transformers with a forklift truck is not recommended, since weight and balance can be problematic, and radiator panels can be easily damaged.

Transformers should be handled with special care when the ambient temperature is below minus 20°C (minus 4°F); otherwise, permanent damage to the

transformer may result.

FAILURE TO FOLLOW THE INSTRUCTIONS BELOW COULD RESULT IN DEATH OR SERIOUS PERSONAL INJURY AND COULD ALSO RESULT IN DAMAGE TO THE EQUIPMENT.

• Lifting equipment, including forklift trucks,

• Keep unnecessary personnel clear while

Jacking, Skidding and Rolling

Double-door style transformers are 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 specied in the “Usual Service Conditions” section of IEEE Standard C57.12.00 General Requirements for

Liquid-Immersed Distribution, Power and regulating Transformers. 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 or other suitable surface, which is rated to support the weight of the completely

Document 2.4.96, Revision 0

! WARNING

▲

cranes, cables, straps, lifting bolts, hoist rings and spreader bars, must be of adequate capacity to safely lift the completely assembled transformer.

unloading and moving the transformer.

March, 2013

Document 2.4.96, Revision 0 March, 2013

Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers

assembled transformer. The transformer should sit ush with the mounting surface, 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 insulating 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 from any obstruction and have adequate clearance to allow the terminal compartment hood or doors to open fully. Avoid locating the transformer in corrosive areas. Remove any shipping braces and packing material that may have been installed at the factory. Hold-down cleats or brackets should be used to securely fasten the transformer to the mounting surface.

Verifying Enclosure Integrity

Howard single-phase compartmental-type padmounted transformers are designed and constructed to be tamper resistant according to the requirements of IEEE Standard C57.12.28 Pad-Mounted

Equipment—Enclosure Security, or C57.12.29 Pad- Mounted Equipment—Enclosure Security for Coastal Environments, as applicable, and therefore need not

be installed 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 modications must be made to the tank or terminal compartment that compromise tamper resistance, the transformer must then be located in a restricted area. Such modications of may void the warranty. Consult with the Howard Industries Transformer Division before making any modications to the transformer.

! WARNING

▲

FAILURE TO FOLLOW THE INSTRUCTIONS BELOW COULD RESULT IN DEATH OR SERIOUS PERSONAL INJURY, AND COULD ALSO RESULT

IN DAMAGE TO THE EQUIPMENT.

Do not modify the transformer in any way that might compromise its tamper-resistant construction.

Grounding

The transformer must be permanently grounded according to applicable local and national codes. Ground the transformer by using ground pads or nuts located inside the terminal compartment at the base of the front panel. 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.

In addition to proper tank grounding as stated above, transformers designed for use on a grounded-wye system must also have all winding neutrals securely and effectively grounded to the system neutral.

! WARNING

▲

FAILURE TO FOLLOW THE INSTRUCTIONS BELOW COULD RESULT IN DEATH OR SERIOUS PERSONAL INJURY, AND COULD ALSO RESULT IN DAMAGE TO THE EQUIPMENT.

The transformer must be properly grounded at all times.

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 cantilever stress on the bushings.

High-Voltage Terminals

Dead-front transformers are designed to use the separable insulated high-voltage connector system dened in IEEE Standard 386. These dead-front transformers come equipped with universal bushing wells only, one-piece (integral) bushings or universal bushing wells with factory-installed bushing inserts. Either loadbreak-rated or non-loadbreak-rated bushings can be provided as specied by the user.

When transformers are provided with universal bushing wells only, bushing inserts must be installed in the eld by the user before cable connections can be made. Bushing well inserts must be compatible

Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers

with the universal bushing wells. Do not use incompatible or improperly rated bushing inserts, or equipment damage could occur. When installing inserts, follow the manufacturer’s instructions accompanying the inserts. Insulated dead-end caps or plugs must be installed on all unused high-voltage bushings before energizing. Shipping dust caps must never be used in place of insulated dead-end caps or plugs.

Live-front transformers are equipped with highvoltage bushings having tin-plated eye-bolt or spade terminals that are suitable for connection with either aluminum or copper conductors to the high-voltage source.

Low-Voltage Terminals

Single-phase pad-mounted transformers are usually provided with externally-clamped, molded, lowvoltage bushings, with or without NEMA standard spade terminals. When threaded terminals are installed, a backup nut should be installed and tightened against the terminal to ensure an adequate connection that will not loosen or overheat. Secondary line leads should be securely attached to the terminals to ensure a low-resistance connection.

Document 2.4.96, Revision 0

March, 2013

Space-Saver™ style transformers may be provided with a block-mounted, wire-lead, low-voltage termination instead of molded bushings. These wire leads are designed to be crimp-connected to the load leads.

+ 25 hidden pages

Howard HI-104 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual