From complete construction and testing of sub-stations to convenient pick-up and delivery service for circuit breakers, GMI has developed specific programs to meet the electrical demands of the mining industry. GMI's engineering department includes personnel who were Chief Electrical Engineers at large coal facilities.

GMI has complete testing, maintenance, start-up, and rebuilding services available for coal mine operations.
Testing & Maintenance Include: Metering, protective relays, motor control centers, low/medium/high voltage circuit breakers, cables, ground beds, switchgear, and transformers.
Start-up Services Include: Verifying construction specifications, bill of materials, circuit schedules are correct, schedule and manage testing of new equipment and prepare turn-over packages.
Rebuilds Include: Oil circuit breakers, molded case circuit breakers, motor control centers, transformers, and complete used sub-station construction.

Companies such as American Energy, Ohio Valley Coal, Rosebud Mining, and CONSOL utilize our services for their electrical engineering needs.





*Customer references & company personnel resumes available at your request.
*Insurance, sample test sheets, & standard rebuild procedures available.

Phone : 814 - 532 - 8870
Fax : 814 - 532 - 8875



Complete Rebuild

  1. Prior to pickup, GMI will need documentation on content of PCB contamination. If you do not have this documentation GMI can provide this service at a quoted price. If oil is PCB contaminated, owner will be responsible for all disposals, including material and handling hardware.
  2. Upon receipt and prior to disassembly, the oil circuit breaker will be tested both mechanically and electrically. Megger, power factor, and micro-ohm resistance tests will be performed and documented.
  3. Non-PCB oil will be drained from oil circuit breaker and can be returned to customer for disposal. GMI will dispose of non-PCB oil at a cost of five cents per gallon.
  4. The circuit breaker tank will be removed, inspected, and thoroughly cleaned with approved electrical cleaning solvent. Special attention will be given to phase barriers, faceplate ports, faceplate supports, and complete tank liner. The exterior will be sandblasted.
  5. A complete visual inspection will be performed for physical damage and cleanliness. Nameplate data will be compared with plans and specifications. Check all gasket covers and seals for weather-tight condition.
  6. All current carrying assemblies will be removed, completely disassembled, and inspected. All silver plated parts will be cleaned, polished, and re-plated when necessary.
  7. All bushing and operating rods will be removed, cleaned, and inspected. Special attention will be given to the insulating compound of resin-impregnated paper.
  8. The operating mechanism will be removed and completely disassembled to its smallest component. All rollers, pins sleeves, and bearings will be replaced. All operating mechanism parts and sub-assemblies, including hardware, shall be re-plated. After plating, the mechanism will be re-assembled according to original specifications.
  9. All wiring will be inspected for fraying; any damaged wires will be replaces with type SIS wires. The complete wiring harness will be tested for proper insulation resistance.
  10. All electrical control devices will be thoroughly cleaned and bench tested for proper operation.
  11. Prior to assembly, all original painted parts will be sandblasted (if needed), coated with primer and painted.
  12. Fill breaker tanks with new insulation oil and provide customer with oil quality analysis.
  13. After sub-assemblies are complete, the entire circuit breaker will be rebuilt according to original manufacturer's specifications.
  14. All final test results will be documented and a copy will accompany each circuit breaker.

The following tests and adjustments will be performed:

Gearhart McKee Inc.
47 Walnut Street
Johnstown, PA 15901
Phone : 814-532-8870
Fax : 814-532-8875

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