Hammond Power Solutions NH SERIES Installation Guide
INSTALLATION, OPERATION AND MAINTENANCE GUIDE
FOR INDOOR/OUTDOOR DRY-TYPE TRANSFORMERS
FOR INDOOR/OUTDOOR DRY-TYPE TRANSFORMERS
WHICH UTILIZE A NH SERIES, NJ1, NJ2, NJ3 OR NJ4 ENCLOSURE
WHICH UTILIZE A NH SERIES, NJ1, NJ2, NJ3 OR NJ4 ENCLOSURE
*Note: This guide is Trilingual
(English, French and Spanish)*
Literature No.: IOMGDDI
Issue Date: May 2010
Safety Precautions
(1) Do not lift or move a transformer without proper equipment and experienced personnel. On
some larger kVA distribution transformers, lifting provisions are provided on the inside of the
enclosure on the core & coil.
(2) Do not off-load the transformer until a full inspection has been completed.
(3) Use terminals only for electrical connections. Flexible connectors are recommended for bus
connections. The transformer terminals are not designed to support the weight of supply or load
cables. Uni-strut supports can be added in the eld providing proper clearances are maintained.
(4) Connections should only be in accordance with the nameplate diagram or connection drawings.
(5) Make sure all power is disconnected before attempting any work on a transformer or inside of
control box and ground all windings.
(6) Make certain all ground connections, line terminals and selected taps are complete and tighened
before energizing the transformer.
(7) Do not attempt to change any taps - primary or secondary, while the transformer is energized.
(8) Do not change connections when the transformer is energized.
(9) Do not tamper with control panels, alarms, interlocks or control circuits.
(10) Do not adjust or remove any accessories or cover plates while the transformer is energized.
No supply cables should come in contact with the core or any live part except the terminal that it
is intende for.
CONTENTS
General 3
Handling 3
Receiving & Inspection 3
Storage 3
Installation 3
Ventilation 4
Accessibility 4
Transformer Sound Levels 4
Cable Connections 4
Grounding 5
Inspection Before Energization 5
Operation 5
Maintenance 6
Dry-out of Transformers 6
Accessories 6
Appendix A 7
Appendix B 8
Figure 1 9
Figure 2 10
Figure 3 11
Notes 12
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INSTALLATION, OPERATION AND MAINTENANCE
OF DRY-TYPE TRANSFORMERS
GENERAL
Dry-type transformers are manufactured to
provide optimum performance for a lifetime of
uninterrupted service. Careful attention to the following
instructions is recommended for safe and reliable
operation.
Installation, operation and maintenance of
transformers should be performed by authorized
persons, familiar with electrical apparatus and the
potential hazards involved.
Warning: Danger! There is the potential of
electric shock whenever working in or
around electrical equipment such as
transformers. Power must be shut off
before any work is conducted on a
transformer.
As with any electrical device, transformers must
be installed according to the requirements of the
national and local electrical codes. Refer to ANSI/IEEE
C57-94 may also be referred to for recommended
installation, application, operation and maintenance of
dry-type transformers.
HANDLING
Transformers are palletized and can either be
lifted via a forklift truck or hoisted by the lifting lugs
provided.
Appropriate lifting equipment should be used
relative to the size of each transformer. For safety
purposes and to protect the transformer, spreader bars
are recommended.
No attempt should be made to lift or move a
transformer from any points on the unit other than
those indicated. Refer to Figures 1 and 2 (pages 9 and
10).
RECEIVING & INSPECTION
Immediately after receiving the transformer, it
should be inspected for any transit damage and for
correctness against the shipping documents.
The unit should be examined for any breaks in its
packaging, dented or damaged enclosures or missing
parts from the packing list.
If any damage is noted, a claim should be led
immediately with the carrier and a second copy of all
pertinent information relative to the order and the
circumstances should be led with the local sales
ofce.
If this examination of the unit takes place
outdoors, caution should be exercised such that
inclement weather would not present further hazard.
STORAGE
Transformers that will not be immediately
installed and energized, should be stored in a clean
dry environment away from any environmental
airborne contaminants.
It is recommended that transformers be stored in
a heated building with the protective plastic wrap still
installed.
INSTALLATION
Enclosures are designed and approved
in accordance with specications
CSA 22.2 No. 47 (General Purpose),
CSA 22.2 No. 94 (Specialty Enclosures),
NEMA 250 and UL 50.
For IEC enclosure equivalents please see
IEC 60529 (Enclosure Classications
Designations).
a) Indoor/Outdoor Dry-Type Transformers with
Enclosures
Most dry-type transformers are supplied with
either a type 3R, 4 or 12 enclosure. Units may be
installed indoors, or outdoors where applicable. If
equipped with a type 1 enclosures, these units are for
indoor use only.
Ventilated enclosures are recommended for
indoor installation but may also be installed outdoors
where weather conditions allow a type 3R ventilated
enclosure to be installed.
For any outdoor location, the appropriate
applicable codes must be followed including cable
installation and hardware suitable for outdoor service.
Water tight couplings must be used at the
knockouts and any holes in the enclosure must be
drilled below any un-insulated live parts, (below LV
terminals).
Dry-type transformers may be located in an
upright position on walls, oors, posts, beams or other
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locations capable of supporting their weight with the
proper accessories attached. Refer to Appendix B
(page 8) for wall mounting kits.
Conventional open ventilated dry-type
transformers have a bottom screen for air convection.
When transformers are mounted above the ground
surface a catcher plate should be installed under each
transformer as a safety precaution against any hot
particles that may fall through the screen in the event
of a faulted condition. Refer to Appendix B (page 8).
It is important that ventilated transformers be
installed in a dry area where the ambient air is clean
and free of dust, dirt, corrosive fumes, moisture, heat
or other adverse conditions. Transformers should not
be installed in such a place having the possibility of
water logging inside the enclosure.
In the event that a transformer has been
subjected to moisture or dampness before installation,
ensure that it is completely cleaned and dried before
energization. The blowing of warmed air through the
transformer is recommended to dry internal
components. Refer to the section on dry-out of
transformers.
b) Indoor/Outdoor Transformers with Non-
Ventilated Type 4, 4X or 12 Enclosures.
However, transformers should not be located in
areas where stored items are likely to interfere with
either natural air convection or the capability to have
them inspected. Passage ways or other areas where
people could be exposed to live parts during
inspection should also be avoided.
Adequate protection should be provided under
any circumstances.
TRANSFORMER SOUND LEVELS
Transformers are an electrically energized
apparatus and by their nature emit sound due to their
component materials.
Transformers are required to meet NEMA
standards for the maximum sound levels permissible.
These sound level standards vary from 40 to 60 DB
and hence, can be an annoyance if located in close
proximity to where people work or reside.
Care should therefore be exercised in selecting
sites for transformers particularly to avoid sensitive
areas like hospitals, classrooms, medical or ofce
facilities.
The following guidelines may be helpful:
Transformers equipped with non-ventilated type
4, 4X or 12 enclosures maybe located either indoors or
outdoors in any similar location noted above. Nonventilated enclosed transformers, although slightly
larger, offer much greater protection against a variety
of elements such as dust, dirt, snow, moisture, rain
etc.
For any outdoor location, the appropriate
applicable codes must be followed including cable
installation and hardware suitable for outdoor service.
VENTILATION
Transformers are required to be installed in an
area where they can be cooled by means of the free
circulation of air where the average ambient
temperature is 30°C (86°F) and should not exceed
40°C (104°F) at any time.
Adequate ventilation is essential for transformers
to meet their nameplate kVA capability. All general
purpose transformers should be located away from
walls or any other obstructions (at least 6 inches when
oor mounted and 4 inches when wall mounted) to
allow free, clean circulation of air through the
ventilation openings or around a non-ventilated unit.
ACCESSIBILITY
NEC standards require that transformers be
accessible for inspection and located accordingly.
Units should be mounted away from corners or
reecting walls or ceilings.
Cable or other exible conduit should be
considered to make connections.
All dry-type transformers are provided with
isolation rubber mounts between the core and
coil assembly and the enclosure. However,
sound absorbing vibration isolators may also be
installed between the transformer and its
mounting surface.
Acoustically absorbing materials could be
considered for walls and ceilings around the
unit.
The location of the unit should be located as
far as practical from areas where sound levels
could be considered undesirable.
CABLE CONNECTIONS
The connecting cable size is determined from the
line current rating of the transformers primary and
secondary windings and may be selected from the
information in Appendix A (page 7). Cables rated for at
least 90°C (194°F) is recommended as are ALC9CU
lugs.
Convenient pre-punched knockouts are provided
on all ventilated transformer enclosures up to 150 kVA
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three phase and 100 kVA single phase, to facilitate
cable entry.
For non-ventilated transformers, pre-punched
knockouts are not provided and the appropriate cable
connector suitable for the application must be used.
Please refer to gures 1 and 2 (pages 9 and 10)
for cable entry locations.
Warning: Never attempt to change connections or taps unless the transformer is
de-energized and all windings grounded.
Side entry of cables is recommended as it leaves
the ventilated areas unobstructed.
Cable connection lugs of plated copper or
aluminum may be used to connect to the transformer
terminals. Terminals should be cleaned and electrical
joint compounds are recommended for use on all
electrical connections.
Refer to the transformer nameplate for primary
and secondary voltage connection combinations and
primary and/or secondary tap positions as applicable.
Transformers received from the factory will have
tap leads installed on the nominal, or 100%, voltage
position. The balance of the tap positions will still be
coated with impregnation material and insulation.
To change taps, it is necessary to remove this
insulation by gently removing the protective coating
from the surface appropriately. The surface of the tap
lead should be clean and coated subsequently with
electrical compound.
NOTE: After installation of cables and
connectors, a minimum of 1” clearance
must be maintained from energized parts
to all case parts.
GROUNDING
secondary and primary to secondary, should be
greater than 10k ohms.
b) Before energizing and connecting any loads,
please measure and verify the output voltage
matches nameplate specications.
c) Ensure correct phase connections. Refer to the
nameplate vector diagram.
d) The load on a delta secondary winding with a 120
volt center tap should not exceed the normal
current rating of the winding. This center tap is
designed for a max. of 5% of the nameplate kVA.
e) When windings are connected in parallel (as in
the case of dual voltage primaries), the primary
taps for all coils must be connected to the
identical percentage tap positions to avoid the
shorting of turns. For tap positions, refer to the
nameplate on the transformer.
f) The enclosure should be grounded with the
appropriately sized conductor.
g) The total load among all the phases should be
balanced as much as possible for optimum
performance of the transformers windings.
Any three phase or single phase load may be
connected to the transformer but the kVA loading
on each phase must not exceed 1/3 of the
nameplate kVA rating.
h) The clearance and tightness of all electrical
connections should be checked.
i) If there is any reason to suspect that the
transformer has been exposed to moisture during
transit or storage, it should be checked for
dryness before energization. This can be done by
making an insulation resistance test. Dry-out
procedures are on page 6.
All core and coil assemblies are solidly grounded
to the enclosure internally to ensure that all conductive
metal parts have the same potential.
The transformer enclosure in turn should also be
securely and effectively grounded as a safety
precaution.
This grounding should be in accordance with
national electrical code standards.
INSPECTION BEFORE ENERGIZATION
For the safe and proper operation of the
transformer, please check and verify the following:
a) The insulation resistance, core to primary, core to
OPERATION
For all relatively normal and clean installations,
dry-type transformers will operate satisfactorily under
normal conditions of energization and load.
For your reference, fully loaded dry-type
transformers may appear warm to the touch,
particularly on the cover of the unit.
Standards permit the temperatures of the cover
to be 65°C (149°F) over ambient. This represents
normal loading and should not be of concern.
Dry-type transformers are designed to operate
continuously at their full nameplate kVA rating.
ANSI C57.96 provides guidance for loading
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transformers under different conditions including:
Ambient temperatures that are varied from the
ambient temperatures required for transformer
operation.
Short time overload as it relates to time and
temperature and the corresponding loss of life of
the transformer.
Overload that results in a reduction of life
expectancy of the transformer.
If the transformer is experiencing increased
temperatures, the following load characteristics
should be considered immediately:
Rigorous motor starting loads or other impact
type loading for which a specic transformer for
that application is required.
Over-excitation of unit due to excess supply line
voltage or current.
Maintenance would include internal cleaning,
tightening of links and bolted connections, servicing
and inspection of auxiliary devices.
Air ducts should be free of any accumulation of
dust and debris and any bolted connections of
terminals must be in good condition.
Vacuuming or blowing of compressed air from
the top down is an accepted practice for removing dust
from the ducts of a transformer coil. Low pressure, dry
air should be used to avoid further contamination of
the windings by foreign material.
The ground connection should also be checked
to ensure a low impedance connection. The
accumulation of ice, snow or any other object blocking
the ventilation should be cleaned up immediately
during the operation of the transformer.
On outdoor units where filters have been
installed, being exposed to the outside atmosphere
can cause the filters to get dirty quickly. A periodic
check of the filters will help avoid filter clogging and
thus transformer overheating. Also, never run the
transformer without the filters properly in place.
Ambient temperatures above standard.
Overload beyond ANSI C57.96 guidelines.
Harmonic distortions of the supply line voltage
and currents.
If overheating is noted, any attempt to add
supplemental fan cooling must be in accordance with
factory installation guidelines. Incorrectly installed fans
can misdirect the airow and cause serious
deterioration of the insulation life in a transformer coil.
Dry-type transformers can be shut down and
stored for extended periods of time without any
deterioration. Care must be exercised to clean and dry
units prior to energization, as previously outlined.
MAINTENANCE
Under normal operating conditions and
environments, dry-type transformers do not require
maintenance. However, periodic care and inspection is
a good practice particularly dependent on the
environmental conditions in which the unit is installed.
Peripheral inspection and external dust removal
may be carried out while the transformer is in
operation. However, access covers must not be
opened under energized conditions.
Internal maintenance must be performed
with a transformer de-energized, isolated
and with the terminals grounded.
DRY-OUT OF TRANSFORMERS
In the event that transformers have been
exposed to moisture such as condensation or rain, it is
advisable to dry-out any unit prior to energization.
Drying may be accomplished by using any hot or
warmed air, radiant heat or internal heat that is
directed through the windings. Heated air should be
allowed to rise up through the windings for a minimum
of twenty four (24) hours after the evidence of
condensation is no longer visible.
Transformers that have been exposed to ood
conditions, direct rain or sprinklers, may not be able to
be dried out appropriately. Contact the transformer
manufacturer for appropriate action.
ACCESSORIES
Dry-type distribution transformers are available
with a number of accessories to facilitate installation.
Consult your local dealer or distributor for the
purchase of any of the items which may be carried in
inventory.
1) Wall Mounting Brackets
Encapsulated transformers have integral wall
mounting capabilities for units up to 285 lbs. Units over
285 lbs. must be oor mounted only.
Ventilated dry-type transformers are normally
designed to be oor mounted only. However, some
ventilated units up to 51kVA are supplied in enclosures
that have integral wall mounting capabilities. These
units can be conveniently mounted on walls, beams or
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poles.
Conventional open ventilated dry-type
transformers have a bottom screen for air convection.
When transformers are mounted above the ground
surface a catcher plate should be installed under each
transformer as a safety precaution against any hot
particles that may fall through the screen in the event
of a faulted condition. Refer to Appendix B (page 8).
2) Sound Isolation Pads
APPENDIX A
AMPACITY RATINGS FOR CONNECTIONS
A. For a single phase transformer
Line Amperes = volt-amperes
line volts
B. For a three phase transformer
All dry-type transformers have rubberized sound
absorbing pads mounted internally between the core
and coil assembly and the enclosure.
For maximum absorption of vibration and
emission of sound, additional sound isolation pads are
recommended for installation between the transformer
and the mounting surface.
These molded neoprene and steel plate
assemblies virtually eliminate vibration noise between
the transformer and the mounting surface.
Consult the manufacture’s catalog for the part
number of the correct isolation pad required
3) Connectors
Connectors for the installation of dry-type
transformers are readily available. These connectors
are suitable for either copper or aluminum cable.
Connectors should be sized and installed in
accordance with your local electrical code
requirements using the best practices to ensure safe
and reliable operation. Cable surfaces should be
cleaned and electrical compound should be used for
all joints.
Selecting Connectors
a) Determine the primary current for the required
transformer from the Appendix A.
b) Similarly, determine the secondary current rating
for the transformer from Appendix A.
c) For 120/240 voltage connections the current
should be based on 240 volts.
d) For 240/480 volt connections, the current should
be based on 480 volts.
Line Amperes = volt amperes
3 X line Volts
Full Load Current Table
Single Phase Transformer
Current in Amperes
kVA
Rating 120V 240V 416V 480V 600V
3 25.0 12.5 7.21 6.25 5.00
5 41.6 20.8 12.0 10.4 8.33
7.5 62.5 31.2 18.0 15.6 12.5
10 83.3 41.6 24.0 20.8 16.6
15 125 62.5 36.0 31.2 25.0
25 208 104 60.0 52.0 41.6
37.5 312 156 90.1 78.1 62.5
50 416 208 120 104 83.3
75 625 312 180 156 125
100 833 416 240 208 166
150 1250 625 360 312 250
167 1391 695 401 347 278
250 2083 1041 600 520 416
333 2775 1387 800 693 555
Full Load Current Table
Three Phase Transformer
Current in Amperes
kVA
Rating 208V 240V 380V 416V 480V 600V
2 5.55 4.81 3.03 2.77 2.40 1.92
3 8.32 7.21 4.55 4.16 3.60 2.88
6 16.6 14.4 9.11 8.32 7.21 5.77
9 24.9 21.6 13.6 12.4 10.8 8.66
15 41.6 36.0 22.7 20.8 18.0 14.4
30 83.2 72.1 45.5 41.6 36.0 28.8
45 124 108 68.3 62.4 54.1 43.3
75 208 180 113 104 90.2 72.1
112.5 312 270 170 156 135 108
150 416 360 227 208 180 144
225 624 541 341 312 270 216
300 832 721 455 416 360 288
450 1249 1082 683 624 541 433
500 1387 1202 759 693 601 481
600 1665 1443 911 832 721 577
750 2081 1804 1139 1040 902 721
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APPENDIX B
LOCATION OF WALL MOUNTING BRACKETS AND CATCHER PLATES
FOR NH3 SERIES TYPE 3R ENCLOSURES
Optional Wall
Mounting Bracket
Catcher Plate
Where Local Code Requires
Catcher Plate
Where Local Code Requires
APPENDIX B
LOCATION OF WALL MOUNTING BRACKETS AND CATCHER PLATES
FOR NH5 & NH6 SERIES TYPE 3R ENCLOSURES
Wall Mounting
Hole Locations
Optional Ceiling
Mounting Bracket
Catcher Plate
Where Local Code Requires
Floor/Ceiling Mounting
Hole Locations
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FIGURE 1
Typical Type 3R, NH Series Ventilated Enclosure Assembly for Three Phase and Single
Phase Transformers.
Notes:
Handling - units are designed to be raised by a fork lift from underneath the pallet. Final positioning of the unit 1.
with the pallet removed can be via a fork lift under the transformer with the forks between the channels.
Shipping - units are shipped on pallets which are to be removed at installation. 2.
Installation - This transformer can be installed indoor or outdoor providing a degree of protection against falling 3.
rain, sleet and external ice formation.
All general purpose/drive isolation transformers should be located away from walls or any other obstructions at 4.
least 6 inches when oor mounted and 4 inches when wall mounted.
DO NOT block bottom ventilation area.5.
Removable front
access panel
Position fork
lift under pallet
Cable entrance
knockouts (2 per side)
For nal positioning
with pallet removed,
fork lift points are under
the transformer
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FIGURE 2
Typical Type 3R, NJ Series Ventilated Enclosure Assembly for Three Phase or Single Phase
Transformers.
Notes:
Handling - units are designed to be raised by a fork lift from underneath the pallet. Final positioning of the unit 1.
with the pallet removed can be via a fork lift under the transformer with the forks between the channels. (Note:
for transformers weighing greater than 2350 lbs should be lifted by removing the top panel and
accessing the lifting provisions on top of the top of the core and coil.)
Shipping - units are shipped on pallets which are to be removed at installation. 2.
Installation - This transformer can be installed indoor or outdoor providing a degree of protection against falling 3.
rain, sleet and external ice formation.
All general purpose/drive isolation transformers should be located away from walls or any other obstructions at 4.
least 6 inches when oor mounted and 4 inches when wall mounted. (Note: These enclosures are not intended
to be wall mounted. They may be mounted on a customer supplied platform.)
DO NOT block bottom ventilation area.5.
Removable front
access panel
Position fork
lift under pallet
Recommended cable
entry location (both
sides). Refer to
outline drawing for
exact dimensions.
For nal positioning with pallet
removed, fork lift points are
under the transformer. Forks
must be inserted all the way
through the depth.
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FIGURE 3
Typical Type 4 & 12, NH Series Non-Ventilated Enclosure Assembly for Three Phase or
Single Phase Transformers.
Notes:
Handling - units are designed to be raised by a fork lift from underneath the pallet. Final positioning of the unit 1.
with the pallet removed can be via a fork lift under the transformer with the forks between the channels.
Shipping - units are shipped on pallets which are to be removed at installation. 2.
Installation - This is a non-ventilated indoor or outdoor enclosure designed primarily to provide a degree of 3.
protection against falling dirt, rain, sleet, snow, windblown dust, splashing water, hose-directed water and that will
be undamaged by the external formation of ice on the enclosure. It is suitable in areas where exposure to large
amounts water from any direction is possible. (Note: not submersible)
All general purpose/drive isolation transformers should be located away from walls or any other obstructions at 4.
least 6 inches when oor mounted and 4 inches when wall mounted.
Lifting Hook
Removable front
access panel
Position fork
lift under pallet
Recommended cable entry location
(either side). Refer to outline
drawing for exact dimensions.
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