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  • Craig Drabyk

Omni PM Project: Double-Ended Substation Maintenance


Electrical preventive maintenance at a 150,000 sq. ft. laboratory building was overdue as per the company’s SOP. Omni, who had completed a major renovation project at the facility 18 months prior, was called in to perform scheduled maintenance of the 4,000 amp double-ended substation that provided power throughout the building.


The PM project required thorough planning and coordination as to which systems would lose power and for how long, and which systems would maintain power through the backup generator and UPS systems. Omni wrote a detailed Method of Procedure, or MOP, that included a safety plan, a sequence of events, and time per task. Maintenance consisted of testing all low-voltage breakers on both sides of the tiebreaker as well as each of the two large step-down transformers. Five days were allotted for this task.


Omni worked closely with maintenance personnel during the project, continually walking the facility and checking to make sure the emergency systems were running and the generator and UPS systems were working properly. Before each medium-voltage switch was opened, electrical loads were carefully swung over to the active side of the substation where it was possible to operate redundant equipment like air compressors, condenser water pumps, and critical exhaust systems.


The electrical testing team began working on their protocol for breaker testing by injecting amperage, followed by testing the transformer and cooling fans, cleaning and checking torque settings throughout the substation, and installing viewing ports on rear access panels for future thermal imaging checks. Upon successful completion of the NETA testing, one breaker was found to be faulty and subsequently replaced with a spare. Several other breakers needed the replacement of LCD backup batteries.


When power was restored and the building was methodically turned back on system-by-system, we did a thorough thermal scan of the substation and tested the Kirk Key interlocks to ensure that everything was operating properly. The project was successfully completed and the facility returned to normal operation nearly six hours earlier than scheduled, much to the owner’s delight.



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