ISO 9001
MGM Three Phase Liquid Filled
Pad Mounted Transformers
BULLETIN 20
T R A N S F O R M E R C O M PA N Y
Standardized Designs)
Three Phase Liquid Padmount Transformers ( LC
APPLICATION
MGM’s three-phase, liquid-filled, padmount compartmental transformers
are specifically designed for use on
underground distribution systems.
Their tamper resistant construction
permits installation in areas accessible to the public without the necessity for special fencing or enclosures. Their visually pleasing low
profile appearance is ideal for shopping centers, schools, hospitals or
commercial buildings. They are
designed, manufactured and tested
to meet or exceed applicable ANSI,
NEMA and IEEE. Standards.
Transformers can be supplied with
the HV arranged for either live-front
radial feed or dead-front radial or
loop feed applications.
CORE & COIL
CONSTRUCTION
MGM’s transformers utilize a fivelegged wound core construction
that is suitable for delta-wye, deltadelta, wye-delta and wye-wye connections. The core is fabricated from
high grade, grain oriented, burr free,
silicon steel and has excellent performance characteristics.
The primary coils are wound with
round or rectangular aluminum or
copper magnet wire depending on
kVA rating, voltage and customer
requirements. The secondary coils
are wound with rectangular magnet
wire or full width copper or aluminum sheet depending on kVA rating, voltage and customer requirements.
The winding insulation
consists of high quality
thermally upgraded
epoxy coated kraft
paper. The thermosetting
epoxy coated kraft
paper, after baking, fuses
the winding together to
provide excellent short
circuit strength. Units
rated 55/65˚C, when
operated at 65˚C, have
an additional 12% kVA
capacity with normal life
expectancy.
RATINGS
75 through 2500 kVA,
TANK
CONSTRUCTION
3 Phase, 60Hz,
65˚C & 55/65˚C Rise
HIGH VOLTAGES
2400 @ 45kV BIL through 14400 @
95kV BIL
LOW VOLTAGES
208Y/120, 240, 480Y/277 & 480 @
30kV BIL
All MGM tanks are manufactured
from precision cut steel and are
braced to withstand the stresses
associated with shipping, installation
and operation. They will withstand
normal operating pressures and vacuums without damage, deterioration
or leaking. The tank base is designed
to permit rolling in directions perpendicular to the centerlines of the
segments. A bolted, gasketed handhole is provided in the tank cover to
allow easy inspection of the interior.
Leak tests are performed before
painting and a final pressure test is
performed prior to shipping.
TERMINAL
COMPARTMENTS
MGM’s terminal compartments are
strong, tamper-resistant and
designed for operating convenience.
The bottom sill is removable to permit skidding over conduit stubs during initial installation. The compartment HV and LV doors are secured
with a rugged three-point latch
assembly that has both a locking
bolt and provisions for a user supplied padlock. For safety reasons the
padlock must be removed, then the
locking bolt loosened before you
can gain access to the LV compartment. A steel divider completely isolates the HV compartment from the
LV compartment and a second safety
bolt must be removed before the
HV door can be opened. Both the
doors and the compartment cover
can be removed to permit easy
installation and servicing. Doorstops
are provided to hold the doors in
the open position.
MGM QUALITY
All transformers are subject to
MGM’s quality inspection checkpoints and each unit must pass the
following tests before being
approved for shipping:
•
•
•
•
•
•
•
•
•
•
Winding Resistance
Impedance
Turn Ratio
Load Loss
Polarity & Phase Relation
Applied Potential Test
No Load Loss
Induced Potential Test
Exciting Current
Pressure Leak Test
STANDARD FEATURES
• Sealed tank construction
• Tank base with jacking and rolling provisions
• Bolted tank cover
• Tank ground pads (ANSI Standard)
• Lifting lugs
• Panel type radiators (as required)
• Bolted and gasketed tamper-resistant
hand hole
• Bolt-on HV & LV terminal compartments
• Removable compartment top cover and
bottom sill
OPTIONAL FEATURES
ACCESSORY
PACKAGE #LCA-1
HV TAPS WITH
EXTERNAL TAP SWITCH
Includes a liquid level gauge, a
dial type thermometer, a pressure vacuum gauge and a 1”
drain valve with sampler (1”
drain valve and sampler is supplied standard on 750 to
2500kVAs).
The following options are available:
ACCESSORY
PACKAGE #LCA-2
Includes same accessories as
LCA-1 except gauges come
equipped with low level alarm
contacts, over temperature and
over pressure alarm contacts.
• Removable hinged doors with door stops
HV OPTIONS
• Three point latching, padlock provisions
and with safety bolt
• Internal HV door safety bolt (holds HV
door closed)
• Steel divider between HV and LV compartments
• Provision for arrestors (live-front only)
• LV epoxy bushings with spade terminals
• Neutral bushing ground strap (Wye LV
only)
• 1” Top filter and filling plug
• 1” Drain plug (75 to 500 kVA)
• 1” Drain valve with sampler (750 to
2500 kVA)
• Auto/manual pressure relief valve
• Nameplate
• Electrical grade mineral oil
• Munsell green #7GY3.29/1.5 paint color
• Live-front radial feed with
three porcelain bushings
with eyebolt or spade terminals (ANSI C57.12.22)
• Dead-front radial feed with
three 200A bushings wells,
200A wells and inserts or
200A one-piece bushings
(ANSI C57.12.26)
• Dead-front loop feed with
six 200A bushings wells,
200A wells and inserts or
200A one-piece bushings
(ANSI C57.12.26)
HV INTERNAL FUSING
• De-energized no load tap
changer
• 2 taps above and 2 taps
below nominal at approximately 2.5% steps
• 4 taps below nominal at
approximately 2.5% steps
HV INTERNAL
LOADBREAK SWITCHES
• 2-Position 200A (On/Off)
• 4-Position 200A with (V)
Blade (Loop-feed only)
• 4-Position 200A with (T)
Blade (Loop-feed only)
HV ARRESTERS
• Distribution Class for livefront construction only
• Elbow mounted arresters
for dead-front construction
only (Loop-feed with elbow
arresters is not available on
LC standardized designs)
MISCELLANEOUS
• High fire point R-Temp or
Silicone fluid
• Bay-o-net expulsion fuses
• Copper windings
• Current limiting fuses in
non-loadbreak dry-well fuse
holders (Loadbreak switch
is required)
• 55/65˚C rise with 12%
increase in kVA at 65˚C rating
• Bay-o-net fuses in series
with internal, partial range,
current limiting fuses
Above fuses are not available at
all kVA sizes and voltages.
Contact Factory for availability
• Special paint colors (ANSI
24, ANSI 49, ANSI 61 &
ANSI 70)
E
5
5
D
20
18
6
7
6
6
A
MGM TRANSFORMER COMPANY
20
5701 SMITHWAY STREET
C
B
CITY OF COMMERCE, CA 90040
kVA
75
112.5
150
225
300
500
750
1000
1500
2000
2500
Transformer Wts.
A
B
62
62
62
62
62
72
72
72
82
82
82
Dimensions-Ins.
C
GALS.
LBS.
66
66
66
66
66
72
72
72
78
78
78
54
54
56
60
62
80
80
82
84
84
98
160
160
170
200
200
270
280
300
390
410
490
2600
2800
3100
3700
4000
5700
6800
8000
10000
11500
13900
Phone: 323-726-0888
Fax: 323-726-8224
Website: www.mgm-transformer.com
e-mail: sales@mgm-transformer.com
Pad and Mounting Detail - Inches
kVA
75 - 150
225 - 500
750 - 1500
2000 - 2500
D
56
62
70
80
E
75
75
81
87
F
63
63
69
75
PAD THICK
6
6
8
8
NOTE: Dimensions and weights are approximate, not for construction, subject to change without notice.
The basic physical arrangements for MGM LIQUID FILLED PADMOUNT TRANSFORMERS are shown below in Figures 1 to 3. For
further information consult MGM Factory.
Live Front-Radial Feed
Ansi Fig. 1,2, and 3 C57.12.22
Dead Front-Radial Feed
Ansi Fig. 1, 3, and 4. C57 12 26
Dead Front-Loop Feed
Ansi Fig. 2, 3, and 4. C57 12 26
Bulletin 20-0600 10/00 Printed in U.S.A.