Rocky Mtn Electric, LLC

22115 CR 52
Greeley, CO 80631

Rocky Mtn. Electric

Transformer Repair & Re-closures

Rocky Mtn. Electric, LLC

Let Rocky Mountain Electric, LLC take care of your transformers needs!

The majority of power transformers and re-closures in operation today are filled with mineral oil. The primary function of the oil is to provide a high dielectric insulating material and an efficient coolant. The effectiveness of the oil as an insulating material is reduced as the moisture level increases, while cooling is reduced as the oil oxidizes. Paper insulation used in transformers will also absorb moisture from the oil, thus increasing power factor readings.

Rocky Mtn. Electric

Burnt bushings

  • Transformer Services:
  • Transformers are checked out at operating voltage before ever leaving our shop. We are capable of producing every voltage necessary at our shop from 24,940 VAC to 12 VDC.
  • Transformer Oil Change with either mineral and the environmentally friendly FR3 oil.
  • Repair burnt or damaged bushings
  • Replace tap changers
  • Repair Leaks
  • Check for PCB's and Cleanse

The oxidation of transformer oil begins as soon as the transformer is energized. A chemical reaction occurs when the oil is exposed to a combination of heat, oxygen, and core and coil components. As the process of oxidation progresses, acids and polar compounds are formed and in turn become sludge. This sludge will then coat heat transfer surfaces on the core/coil and the tank/radiators, reducing the heat transfer capabilities.

Rocky Mtn. Electric


  • Reclosures Services:
  • Test for proper operation
  • Repair Leaks
  • Change oil- mineral or FR3
  • Transformers should be checked on a annual schedule for:
  • Rust
  • Oil level
  • Oil temperature
  • Tank pressure
  • Signs of leaking in or around:
    • Base of transformer
    • Cooling fins
    • Primary bushings and inserts
    • Secondary paddles
    • Temperature & Level Gauge
    • Drain fittings
    • Tap changer
    • Bayonet fusing
    • Transformer switch
    • Loop feed switch
  • Cooling fins should be checked for:
    • Cleanliness
    • Bent and/or Leaking Fins
    • Proper operation of fans and thermostats (where installed)
  • Proper operation of pressure relief valve. Laws now require a pressure relief valve on all transformers, Many older transformers need this installed to meet new regulations and to better protect the transformer.
  • Primary and Secondary connections
  • Primary side tamperproof bolt
  • Security of entry into transformer compartments including tamperproof bolt and seal or lock.

Oil should be changed every 20 years, and may require changing sooner, if transformer has seen major faults, lightning or stress from frequent overloads.

As new regulations and other environmental concerns arise mineral oil may need to be replaced with FR3 type oil. Rocky Mtn. Electric, LLC carries both mineral and FR3 oils for transformers and re-closures.

For a Free Electrical Estimate or any Questions, please Contact Us or call (970) 395-0536.

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