Maintaining Automatic Transfer Switches for Reliability and Longevity

Properly maintained automatic transfer switches (ATSs) can provide decades of reliable, trouble-free, and cost-effective load switching between primary and standby power sources. However, to reduce costs, some owners may contemplate implementing a reduced scope of service and/or using low-cost service providers that are not trained or supported by the ATS manufacturer. This document describes avoidable costs that could result from unintended outcomes of low-cost service, and explains the scope of maintenance that will provide reliable ATS service for decades to come.



Reviewing potential problems resulting from improper service shows why it is important to implement a maintenance program based on thorough procedures performed by qualified service providers. In one instance, a hospital awarded a contract to maintain 18 ATSs to a low-cost, third-party service provider. Following the initial service, one of the ATSs failed while transferring power during a routine test. The event damaged both the ATS and the facility’s generator control system, leaving the hospital without reliable backup power. Subsequent inspection found the remnants of a rag in the affected ATS, which had caused one of its transfer switching mechanism linkages to bind. A flammable lubricant was also found to be dripping from components in all of the transfer switches.

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