MGM 600V CLASS DRY Owner's manual

MGM TRANSFORMER COMPANY
5701 SMITHWAY STREET • CITY OF COMMERCE, CALIF. 90040
[phone] • FAX [phone]
www.mgmtransformer.com
600V CLASS DRY - TYPE
DISTRIBUTION TRANSFORMER
INSTALLATION, OPERATION, AND
MAINTENANCE MANUAL

MGM 100-10
MGM TRANSFORMER COMPANY
5701 SMITHWAY STREET • CITY OF COMMERCE, CALIF. 90040
[phone] • FAX [phone]
www.mgmtransformer.com
Installation, Operation
And Maintenance Manual
For Dry Type Transformers
UP TO 600 VOLTS
ALUMINUM OR COPPER
80° C, 115° C or 150° C RISE
WARNING
Electrical potentials hazardous to human life can exist within this equipment when it is
energized. Disconnect all input power before opening the case or touching the internal
parts
The information contained herein may not cover all variations in equipment supplied or
provide for all contingencies that might arise during the installation, operation or
maintenance for this equipment. If there is any question regarding the above items,
contact your supplier.
IT IS EXPECTED THAT ANY INSTALLATION OR MAINTENANCE WILL BE PERFORMED
BY QUALIFIED PERSONNEL ACCORDING TO LOCAL, STATE, AND NATIONAL CODES.

MGM 100-10
FOR ADDITIONAL INFORMATION OR ASSISTANCE VISIT MGM TRANSFORMER COMPANY ONLINE AT
HTTP://WWW.MGMTRANSFORMER.COM
General
Read the entire manual before attempting to perform
installation of this transformer. Dry type transformers are
suitable for indoor or outdoor use depending upon the
construction of the enclosure as well as the ability to
protect the transformer from unwarranted access to live
parts. They are cooled by the free circulation of air
through the enclosures, the average ambient
temperature over 24 hours should not exceed 30° C
(86°F), the maximum ambient temperature should not
exceed 40° C (104°F) or as otherwise specified in the
specification. Overheating may occur if the air flow is
restricted, the transformer is overloaded, it is supplied
with over or under voltage, or operated at other than
rated frequency.
Inspection upon Receipt
Units are shipped in upright position and should arrive
that way. Upon arrival, all units should be inspected for
damage during shipment. Unpack and examine for
broken or loose parts. Careful inspection should be
made of transformer coils, wiring and insulators. What
appears to be minor damage in these areas may result
in an open or short circuit. Claims for damage should be
filed with the transportation company and an MGM
Transformer Company representative must be notified
immediately. For superficial or minor case part damage,
spare parts may be available, contact an MGM
Transformer Company representative.
Handling
All transformers must be kept in the upright position in
which they are shipped. Lifting cables or chains should
be used with spreader bars to avoid damage to the finish
or parts. When there are no external lifting provisions,
the top cover should be removed and cables or chains
secured to the top core-clamping channels or angles
where holes are provided for this purpose.
Lifting with hand trucks or fork lift trucks is permissible if the
blades or forks are long enough to pass completely under
the case. Since most general purpose transformers have
a high center of gravity, extreme caution should be
exercised when lifting or moving the units.
If it is necessary to move ventilated dry-type transformers
during inclement weather then they should be thoroughly
protected against the entrance of moisture.
Storage
Storage areas should be as clean and dry as possible
without extreme temperature variations. Protective
wrappings should be left intact until the transformer is
moved to its permanent location. Dry type transformers
stored under extremely wet or dusty conditions must
have cleaning and drying operations performed before
the unit can be energized. (See Maintenance Section.)
Installation Location
Factors to be kept in mind when choosing a location
for dry type transformers are: accessibility, ventilation,
environmental conditions, and noise (see ‘Reducing
Sound Levels’). Installation should be made in an area
reasonably free from dust, excessive moisture,
fertilizers, chemicals and other corrosive fumes or
vapors and separated from flammable materials in
accordance with the N.E.C.
General purpose dry type transformers are supplied in
enclosures rated for indoor installation. Weathershield
kits are available to convert these enclosures for UL
listed outdoor Nema 3R use. The appropriate kit can be
obtained from an MGM Transformer representative. For
units up to 75 kVA, wall mount brackets are also readily
available. Even with a properly attached weathershield
kit, no transformer should be hosed off, or placed in the
catchment area of a water sprinkler.
In all locations dry type transformers must be installed
in the upright position in an area with free air
circulation. Unless otherwise specified in the N.E.C or
applicable local codes, a minimum distance of six
inches from adjacent structures should be maintained.
Fencing in the transformer to prevent unauthorized
access is strongly recommended.
Room Requirements
Dry-type transformers located indoors should comply
with the application requirements of N.E.C.
The room in which dry-type transformers are located
should be sized to permit locating transformers with
sufficient spacing between units and sufficient
clearances to walls and other obstructions (minimum of
six inches or as specified below nameplate) to permit air
circulation. Sufficient space should also be provided to
permit routine inspection and maintenance.
Adequate ventilation is essential for the proper cooling
of transformers. Clean, dry air is desirable. Filtered air at
or above atmospheric pressure may reduce
maintenance if dust or other contaminants present a
particular problem. When transformers are located in
rooms or other restricted spaces, sufficient ventilation
should be provided to hold the air temperature within
established limits when measured near the transformer
inlets. This will usually require approximately 100 ft3/min
of air per kilowatt of transformer loss. The area of
ventilating opening required depends upon the height of
the room, the location of openings, and the maximum
loads to be carried by the transformer. Room ventilation
should not impede normal circulation of air through the
transformer.
When possible, the air inlet to the room should be near the
floor with the outlet in the opposite upper end of the room.
The exhausting air should not exceed 15°C over the inlet
air temperature. When necessary, forced air exhaust
should be used to maintain this maximum differential.

MGM 100-10
FOR ADDITIONAL INFORMATION OR ASSISTANCE VISIT MGM TRANSFORMER COMPANY ONLINE AT
HTTP://WWW.MGMTRANSFORMER.COM
Connections
Cautions: Make only those connections shown on the
nameplate or connection diagram. Before energizing,
check all tap jumpers for proper locations, and all bolted
connections for tightness. All three sets of taps on a
three phase transformer must be connected in the same
location for each phase. For instructions on how to read
nameplates and connection diagrams, please visit the
documentation section of our website at
http://www.mgmtransformer.com .
All transformers, with bottom connections are designed for
easy accommodation of cable sizes in accordance with
NEC. Cables which will carry less than 100 amperes may
have a 60° C temperature rating or higher, and cables
which will carry 100 amperes or more must have a 75° C
temperature rating or higher. All cables should be in the
lower part of the transformer enclosure in accordance with
markings on the enclosure.
Use 90° C cable sized to 75° C ampacity for the units
having terminals located above the coils. After the first
thirty days of service, re-tighten all connecting lugs and
bolts. Depending on the kVA rating, the transformer may
have flexible leads with bolted type wire terminals,
copper/aluminum (CU/AL) lug connectors, or simply termi-
nation pads for mounting your own crimp or lug type
terminations. The table below shows required torque for
installing bolted wire connectors and cables in lug type
connectors.
Bolted Wire Connections Lug Type Connectors
Bolt Size Torque
Foot Pounds
Wire Size (AWG) Torque
Inch Pounds
1/4 – 20
5/16 – 18
3/8 – 16
1/2 – 13
5/8 – 11
3/4 – 10
10
15
20
40
55
80
#14 to #8
#6 to #4
#3 to #1
1/0 to 2/0
3/0 to 200 MCM
250 to 400 MCM
500 to 750 MCM
70
100
120
150
210
250
300
NOTE: Tighten, wait several seconds, then re-tighten all
connecting lugs and bolts.
Always use two wrenches when tightening or
loosening bolted connections to prevent damage.
Minimum electrical clearances in the installation of lugs
and cables must be per ANSI and NEMA Standards. All
electrical clearances that are questionable must be
insulated for the applied voltage. Particular care should
be taken with shielded cables, so that the ground termi-
nation of the cables has sufficient clearance from all the
manufacturers installed live parts, including parts that
appear to be insulated.
Grounding
It is the responsibility of the installer to ground the
transformer enclosure assembly to the ground system in
accordance with the latest revision of the NEC Section
450-10, NEC Article 250 and ANSI/IEEE Std. 144.
Reducing Sound Levels
Transformer noise originates within the steel core. It is
an inherent characteristic of all transformers and cannot
be completely eliminated. Therefore, care should be
exercised in the selection of the transformer location,
particularly in buildings where the ambient sound level is
quite low. A transformer's sound level is quite often
unintentionally amplified by improper installation, which
makes the transformer appear to be considerably louder
than it actually is. Transformer sound levels are
amplified by sound waves in the air being reflected from
surrounding objects and resonance of mounting
construction and electrical connections. This situation
should be avoided wherever possible. Transformer
sound level problems can also be further minimized by
following these installation suggestions:
1. The core and coil assembly is isolated from the case
with vibration mounts, which are tightened to
prevent damage during shipment. Loosen the bolts
which secure the core and coil to the case by one
turn to reduce the pressure on the vibration pads.
Make sure to re-tighten these bolts before moving
the transformer to another location. If the
transformer is located in a Seismic Zone 4 location it
is best to keep the bolt tightened.
2. The case may be installed on vibration mounts for
additional reduction of sound levels.
3. Flexible conduit couplings should be used to reduce
vibration transfer from the case to the incoming and
outgoing conduit.
4. The installation should be in an area where the
sound will be least objectionable.
5. Avoid stairway and hall areas or reflecting objects
which resonate or echo. Concrete or masonry walls,
floors and ceilings are excellent sounding boards. If
these and other reflecting surfaces cannot be
avoided, acoustic absorbing materials should be
used to cover them.
6. Mounting the transformer on walls, balconies or
floors which have relatively light mass should also
be avoided. The possibility of amplifying the sound
waves in the structure will be greatly reduced if the
weight of the mounting surface corresponding to the
projected area of the transformer is equal to, or
greater than the weight of the transformer. Surfaces
which may distort or strain the transformer case
should be leveled or squared before installation.
7. Shrubbery can be planted near the unit on outdoor
installations to break up the sound pattern. Make
sure all sprinklers are aimed away from the
transformer.

MGM 100-10
FOR ADDITIONAL INFORMATION OR ASSISTANCE VISIT MGM TRANSFORMER COMPANY ONLINE AT
HTTP://WWW.MGMTRANSFORMER.COM
Prior To Energizing
After the installation is completed, remove any debris
from the bottom of the cable compartment and from
under the transformer. After the transformer has been
installed, but before it is energized, all shipping braces
should be removed. Tighten securely all external bolts to
eliminate any vibrations. Check tap jumpers for proper
location, and all bolted connections for tightness. (use
two wrenches)
Parallel Connecting
The transformer may be connected in parallel with other
transformers if the phase angle shift is the same; phase
rotation is the same; transformers’ turns ratios and
voltages are within a 0.5% range; and the percent of
impedance on the same kVA base is within a ± 7.5%
range.
Maintenance
Although dry type transformers require less maintenance
than liquid filled transformers and other electrical
devices, periodic cleaning and inspection on the average
of at least once a year should be performed except
under extraordinary conditions, in which case the
inspections should be made more often.
The unit must be de-energized before checking for loose
connections or parts, accumulations of dirt on insulating
surfaces, and dust which tends to restrict air flow. The
windings may be cleaned with a vacuum cleaner, a
blower, or with compressed air. The use of a vacuum
cleaner is preferred as the first step in cleaning followed
by the use of compressed air or nitrogen. The
compressed air or nitrogen should be clean and dry and
should be applied at not more than 25 psi. Lead
supports, taps, terminal boards, bushings and other
major insulation surfaces should be brushed or wiped
with a dry cloth. The use of liquid cleaners is undesirable
because some of them have a deteriorating effect on
most insulating materials.
As long as the transformer is energized, humidity
conditions are unimportant. In the event that a dry type
transformer is de-energized and allowed to cool to
ambient, consideration must be given to the possible
effects of humidity. If moisture is noted, it should be
removed by drying with heated air from a blower, with
the maximum temperature of 110°C or 230°F. The heat
must be distributed in the enclosure. Incandescent
lamps or heaters may also be used if the same
temperature limitations are observed.
Lighting Tap Applications
Most transformers with 240V delta secondaries have a
120V single-phase lighting tap. The maximum single-phase
120V load can not exceed 10% of the three-phase kVA
rating. The load must also be balanced at 5% maximum
between X1 and X4 and 5% between X2 and X4. The
three-phase kVA rating will be reduced by 15% when
lighting tap is used to maximum capacity.
Dielectric Insulation
Transformer insulation system is designed to protect the
integrity of the transformer to the BIL rating on the
nameplate. If exposed to lightning, switching surges or
severe transients, additional protection such as surge
arrestors, surge capacitors or a higher BIL rating should
be provided.
Ambient Temperature
Limiting ambient temperatures for normal service
conditions are specified in ANSI Standards for
Transformers. Transformers depend entirely on the
surrounding air for adequate ventilation. The ambient
should not exceed 40° C (104° F) and the average
temperature of the air for any 24 hour period should not
exceed 30°C (86° F). For operation at higher ambient
temperatures, transformer loading should be reduced
0.6% of rated kVA for each degree above 30° C average
ambient to a maximum of 50° C. The use of transformers
in cooling air above 50° C is not covered by this guide,
and the manufacturer should be consulted before such
installations are made.
Altitude
Transformers are normally designed for operation at
altitudes up to 1000 meters (3300 feet). To operate a
transformer above 1000 meters, it is necessary to
reduce the kVA load and to increase the electrical
insulation clearances between energized terminals.
Refer to NEMA ST20-1986 for detailed guidelines.
References
All transformers are manufactured per NEMA and
ANSI/IEEE standards. Where the UL Label is affixed,
the transformer conforms to UL requirements.
Further information may be found in ANSI/IEEE
Standard C57.94. Recommended Practice For
Installation, Application, Operation And Maintenance Of
Dry Type General Purpose Distribution And Power
Transformers.
When you need Service
If you need service on products manufactured by MGM
Transformer we are ready to serve you. Contact the
nearest Sales Office for more information.
Terms and Conditions
Please refer to your copy of the “Terms and Conditions” for
warranty and product liability information. The “Terms and
Conditions” arrived along with your order acknowledgment,
are printed on the reverse page, and are available online at
www.MGMTransformer.com.

MGM TRANSFORMER COMPANY
5701 SMITHWAY STREET • CITY OF COMMERCE, CALIF. 90040
[phone] • FAX [phone]
www.mgm-transformer.com
APPLICABLE LAW: MGM Transformer is a
California corporation doing business in California
and as such requires that any litigation brought
against the company have exclusive venue in
California. Applicable law may be either the laws
of the state of California, or the U.C.C. This
requirement of California jurisdiction is mandatory
despite the fact that MGM ships products
nationwide.
STANDARD CONDITIONS OF SALE: The
information contained herein covers the terms and
conditions under which MGM Transformer
Company products are sold. Any modifications of
these terms and conditions, unless agreed to in
writing, will not be recognized.
CHANGES: Prices, conditions and terms of sale
are subject to change without notice.
TERMS: Terms are 1% ten days, net thirty (30)
days from date of invoice. The Company may at
any time require full or partial payment in advance.
If the purchaser delays shipments, payment shall
become due from the date when the Company is
prepared to make shipment. Apparatus held for the
purchaser shall be at the risk and expense of the
purchaser.
QUOTATIONS: Quotations, written or verbal, are
subject to the conditions of sale listed herein.
Written quotations automatically expire thirty (30)
calendar days from the date issued and are subject
to withdrawal by notice within that period. Verbal
quotations automatically expire twenty-four (24)
hours from the time issued.
ACCEPTANCE OF ORDERS: All orders shall be
written and are subject to acceptance at the factory.
EQUIPMENT DESTINED FOR FEDERAL,
STATE, OR LOCAL GOVERNMENT: MGM is
not bound to honor quotations for equipment
destined for Federal, State, or Local Government
unless MGM knows at the time of quoting that it is
a government job as these orders frequently involve
higher administration costs.
TAXES: Prices do not include sales, use, excise, or
other taxes. If any products or materials delivered
hereunder are determined to be taxable under any
sales, use, excise, or other taxes applicable to the
sale or delivery of personal property, Purchaser
shall be liable for and pay the same without
recourse against Seller, or in lieu thereof furnish
Seller with a tax-exemption certificate acceptable to
taxing authorities.
ERRORS: All stenographic and clerical errors are
subject to correction.
DELIVERY: MGM can arrange for apparatus to be
sold F.O.B, point of shipment; or freight prepaid.
UNLOADING AND DEMURRAGE: Unless
stated otherwise in our quote, it is the customer’s
responsibility to unload all shipments whether by
rail or truck. All demurrage charges are customer
responsibility.
MGM recognizes that sometimes the size or weight
of shipments requires the customer to make prior
unloading arrangements. In such cases the
customer shall advise MGM prior to shipment the
hours during which shipments cam be received and
the notice required before delivery. MGM will then
reflect these arrangements on the bill of lading.
Origin method of shipment and routing: The
company will determine the point of origin, method
of transportation, and the routing of shipment.
Purchasers requiring other routings will be billed
any excess in transportation charges.
PENALTY CLAUSES: The Company will not
pay or be liable for any penalty, either liquidated
or otherwise, for late delivery or installation.
Shipping dates are estimated and are dependent
upon prompt receipt of all information and material
necessary. The Company shall also not be liable for
any unforeseen delay, i.e. acts of God or inability to
obtain necessary labor, materials, or manufacturing
facilities due to such causes.
CANCELLATION: Buyer shall not have the
right to cancel purchase orders because of
reasonable delays in deliveries. Any order or
contract if cancelled requires payment based on the
followingtable:
Purchase Order Released……..20%
Engineering Complete………..50%
Purchasing Complete………..100%
Changes: The customer has the right to change
their order, in writing, if agreed upon by seller.
Should such changes alter the amount due or time
required for production, an equitable adjustment of
price and/or time shall be made. Changes affecting
function or performance of item ordered may not be
made without prior written consent from MGM.
Warranty: MGM transformers are guaranteed to
be of the highest quality. They are further
guaranteed, when used for the purpose intended and
operated under normal conditions to give
continuous and efficient service. MGM Transformer
Company agrees to correct any defect in
workmanship or material, which may develop under
proper or normal use during the period of one year
from date of shipment. Should a transformer fail
within the warranty period, MGM will issue
authorization to return the failed transformer to one
of MGM’s plants, freight prepaid. At MGM’s
option the failed transformer will be repaired,
replaced or credit will be issued depending on the
nature of the failure. A repaired transformer or
replacement will be delivered to the purchaser
F.O.B. point of shipment with freight prepaid.
Repair, replacement or issuance of credit with
regards to the defective transformer will constitute
fulfillment of all MGM’s liabilities in respect to
said transformer. This guarantee does not include
incidental expenses, such as expense of removing
and replacing the transformers from service. This
warranty is exclusive and in lieu of all other
warranties of quality whether written, oral or
implied (including any warranty of merchantability
or fitness for purpose.)
LIMITATION OF LIABILITY: MGM shall not
be liable in contract or in tort for special, indirect,
incidental, or consequential damages, such as but
not limited to, loss of profits or revenue, loss of use
of power system, cost of capital, cost of purchased
or replacement power, or claim of customers of
purchaser for service interruptions set forth herein
are exclusive, and the liability of MGM with respect
to any contract, or anything done in connection
therewith such as the performance of breach
thereof, or from the manufacture, sale, delivery, re-
sale, installation, repair or use of any equipment
covered by of furnished under this contract whether
in contract, in tort, or otherwise, shall not exceed
the price of the equipment or part on which such
liability is based.
RETURNING APPARATUS:
A. In no case are goods to be returned without
first obtaining the Company’s written
permission.
B. Any material returned and not authorized will
not be signed for and will be returned back
deadhead to the sender.
C. Material accepted for credit is subject to a
MINIMUM restocking charge of 20% plus all
transportation charges.
D. Material built to order is not subject for credit
under any circumstances.
E. If return is caused by fault of the Company,
full credit will be allowed.
EXPORT PACKING: Refer to factory for
additional cost of export packing.
SPECIAL CONDITIONS FOR POWER
TRANSFORMERS: Because of their nature, size,
and weight, the following additional policies apply
topowertransformers:
A. MGM Transformer Company reserves the
right to determine the best mode of shipping.
All shipments will be made by truck unless
size or weight makes this impossible.
B. Prices quoted for power transformers do not
include high voltage or low voltage bushing
connectors unless specified in the inquiry and
quotation.
C. Field inspection or supervision is not
included
D. Standard testing is included. Special testing
or witness testing are extra cost items.
1. In the event of default by buyer of any
obligation buyer agrees to pay costs and
expenses including attorney fees, costs of suit
and interest at 2% per month.
Terms and Conditions