Oil Filled substation Transformers by MGM Transformer Company Skip to content


High Rise Transformer


Liquid filled substation transformers are used in a wide variety of Commercial and Industrial applications. MGM’s high grade materials and state of the art technology will deliver years of high reliability service.

MGM’s liquid filled transformers can be designed with a number of different dielectric coolant choices including Mineral Oil, Silicone Fluid, or Fire-Resistant Hydrocarbon Fluid (FR3) and use a tank construction with precision cut steel braced to withstand the stresses of shipping, rolling and jacking. 

MGM designs and manufacturers each component of it’s liquid-filled transformer in-house which allows it to manage complex, customized applications including VaporTran replacements. Not only can MGM design units to fit within the existing VaporTran footprint, but they can also support the decommissioning and removal of the VaporTran unit.


  • Type I insulating mineral oil
  • 60 Hertz operation
  • 65°C average winding rise
  • Side-mounted bushings
  • HV /LV flange connections
  • Stainless steel nameplate
  • ANSI 61 paint finish, 5 mils thick
  • Pressure test valve
  • ANSI grounding pad
  • Pressure-vacuum gauge
  • Top filter press connections
  • Liquid level gauge
  • Liquid temperature gauge
  • Provisions for jacking and lifting
  • NEMA two-hole ground pads
  • Panel-type radiators as required.
  • Drain/filter valve with sampling device
  • Base suitable for rolling and skidding
  • Dial-type thermometer with maximum indicating hand
  • Externally operated de-energized tap changer providing (2) 2½% full-capacity taps above and below nominal
  • 55/65°C average winding rise
  • Forced air cooling
  • Future fan wiring and control
  • Removable radiators
  • Pressure relief device
  • Winding temperature indicator
  • Devices with alarm contacts
  • Top filter press valve
  • HV lightning arresters in ATC
  • Current transformers
  • Stress cones
  • Special impedances
  • Low loss
  • Special ambient
  • Special/low sound level
  • 50 Hertz
  • Retrofit to specific dimensions
  • Neutral grounding resistor
  • Rapid rise pressure relay, cover mounted
  • HV & LV air terminal compartments
  • Tertiary windings for Wye-Wye connections
  • 6, 12, 18 and 24 pulse drives applications
  • Non-standard loading conditions (i.e. Harmonics/K-factor)

Mineral Oil Filled
The oil-filled unit is the least expensive transformer, and is suitable for mounting outdoors or indoors enclosed in a vault. The oil used in MGM transformers meets all the requirements of ANSI C57.106 and ASTM D-3487, has high dielectric strength, is free from impurities, is durable and has a high flash point 

Silicone Filled
The silicone fluid selected for use in MGM transformers is a clear, liquid silicone polymer (polydimethyl-siloxane) that has been specially processed to meet exacting dielectric specifications. To obtain an optimum combination of heat transfer and fire-resistant properties, the transformer silicone fluid has a viscosity of 50 centistokes at 25°C. 

Environmentally Friendly Dielectric Liquid FR3
A Fire-Resistant Hydrocarbon Fluid (FRHF) dielectric coolant formulated for use in distribution transformers is available when its unique electrical, thermal and safety properties are advantageous. It is non-toxic and readily biodegradable. It is also referred to as a High Fire Point Fluid, a High Molecular Weight Hydrocarbon or a LessFlammable Dielectric Liquid.


ANSI standards enable only 5% maximum harmonic content of load current for standard distribution transformers. If the distribution load consists of electronic power supplies, electronic ballasts and adjustable speed motor control, it would be prudent to investigate the harmonic content and, perhaps, specify a “K Rated” transformer. MGM can help you determine required “K Factor” from the applicable harmonic current spectrum.


MGM’s miter cut core is fabricated from high grade grain-oriented silicon steel, hand stacked to give low losses and excitation current, and tightly clamped and braced to mechanically strong coils are fabricated from extruded rectangular conductors. In the larger units, full width strip is used in the low voltage windings, reducing short circuit stresses and providing improved heat transfer for cooler coil operation. Conditioned strip edges eliminates burns and sharp edges. Only thermally upgraded insulation is used throughout for extended life at 65C. Units rated 55/65C when operated at 65C have 12% added capacity, with normal life expectancy


MGM tanks are rugged, constructed from precision cut steel and braced to withstand the stresses of shipping, rolling and jacking. They will withstand a pressure or vacuum of 7 psi without damage, deterioration or leaking. All tank bases are designed to permit rolling in any direction perpendicular to a tank wall. A bolted hand hole is provided in the cover, which is welded on. Leak tests are performed before tanking and pressure tests prior to painting. Any combination of throat, flange or terminal chamber are available to match the requirement of a variety of high voltage switches and low voltage distribution sections. Custom design termination is also available for matching existing switch gear in the case of PCB change-outs.



All tests are performed in accordance with the latest revision of ANSI Standard Test Code for Transformers

  • Exciting current at rated voltage
  • Polarity and phase-relation tests on the rated voltage connection
  • Ratio tests on rated voltage connection and all tap connections
  • No-load loss at rated voltage
  • Resistance measurements of all windings
  • Insulation power factor test
  • Impedance and load loss
  • Applied potential tests
  • Induced potential test
  • Pressure leak test
  • Impulse tests
Need it fast? We can deliver. Emergencies happen and we can expedite the manufacturing of your units to meet your delivery requirements. Ask about our Bull Rush program when you place your order and we can manufacture and ship your unit in as fast as 2 working days!

MGM Transformer Company can manufacture your units at our 120,000 square foot plant in the U.S. and source the raw materials solely from American companies if required. By doing so we can certify your units to be compliant with any of the various “Buy U.S.” statutes (either state or federal). Please make sure to specify your requirements at the time of order.

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