Preventive Maintenance Could Have Saved Thousands

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Preventive Maintenance Could Have Saved Thousands

Paying For Neglect

Comprehensive Electrical Preventive Maintenance (EPM) is an essential part of a facility’s overall maintenance program. EPM must be routinely performed to ensure electrical equipment is operating properly and within manufacturer’s guidelines in order to provide safe, reliable, and efficient operation.
A recent claim for damage to the primary substation at a southeastern food distributor’s warehouse illustrates what can happen and how much it can cost when EPM and routine examinations are not performed on electrical distribution equipment. The damage caused a power outage and generators were rented to prevent spoilage to refrigerated product while the equipment was being repaired.
In addition to a large deductible, this claim cost the insured several thousand dollars for items that were not damaged from the accident, but were repaired or replaced because they were not maintained or were previously damaged. All major repairs could have been avoided if a routine EPM program was in place.

Substation Damage

A fault occurred to bus bar inside the insured's primary outdoor substation. The substation was comprised of several housings (cubicles) arranged together with a weatherproof enclosure onto and around the housings. The investigation by Hartford Steam Boiler revealed damage to bus resulted from corona, which is an electric discharge caused by ionization of the atmosphere surrounding high-voltage conductors.
The corona occurred over a significant period of time. It causes severe local overheating of insulation resulting in carbonization that produces leakage tracks in organic materials. Leakage paths from corona tracking can result in a line-to-line or line-to-ground flashover, which occurred in this case.
The substation cubicles were found rusted and corroded, as were the main and feeder circuit breakers. This rust and corrosion formed over a significant period of time. The cubicle space heaters, circuit breaker capacitive trip devices, and the control power transformer (CPT) terminal blocks were found electrically damaged. This was likely due to a surge, which occurred sometime prior to this accident.

EPM and Routine Exams are Key

The space heaters function to prevent build-up of condensation inside the outdoor substation. The CPT supplies power to the cubicle space heaters and circuit breaker trip devices. Without the power supply from the CPT, these heaters and trip devices could not function. Over time, condensation formed inside the equipment, causing the cubicles and mechanical components of the circuit breakers to rust and corrode.
The moisture inside the cubicles initiated corona activity on the bus bars at insulating supports between the cubicles. The corona slowly burned away at the insulating sleeve covering the bus bars until the fault occurred. Sometime prior to the failure, a crackling noise could be heard coming from within the substation, which is a classic indication of corona, yet no one investigated further.
No EPM was performed on the substation for at least 15 years. More than a year prior to the failure, EPM was recommended to the insured, but they did not implement a program. A routine, comprehensive EPM program could have uncovered the problems with the CPT and space heaters, avoiding the corona and the rusted and corroded circuit breakers and cubicles, and the costs associated with the bus damage.
Luckily, no faults occurred downstream of the circuit breakers since the trip devices were previously damaged and the breakers were not capable of automatically tripping to clear a downstream fault.
The maintenance costs to repair and service the rusted and corroded circuit breakers and cubicles, and the costs to repair or replace the space heaters, trip devices and CPT amounted to tens of thousands of dollars. These costs were separate from the costs to replace the damaged bus and to rent generators. In addition, the insured had a large deductible that had to be taken into consideration.

Lessons Learned

An effective EPM program enhances equipment performance and reliability, and reduces the likelihood of pre-mature equipment failure. Electrical preventive maintenance costs less than reactive maintenance since there are fewer, if any, major repairs; and the annual EPM costs can be spread over time (annual distribution) versus a huge one-time cost of repair.
By choosing to de-energize the equipment and perform EPM at a time convenient for you, an unscheduled power outage and damage that seems to occur at the most inopportune time can be avoided. When something doesn’t sound or look right, investigate it immediately. Routinely check your equipment for adverse conditions before they result in damage.
Disclaimer statement:

All recommendations are general guidelines and are not intended to be exhaustive or complete, nor are they designed to replace information or instructions from the manufacturer of your equipment. Contact your equipment service representative or manufacturer with specific questions.

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