New Littelfuse device aims at arc flash prevention

Ground fault relay manages safety and avoids nuisance trips
By Plant Engineering Staff December 2, 2008

To avoid nuisance tripping that occurs with conventional ground fault relays , maintenance workers tend to increase trip points above sensitive levels. However, this defeats the purpose of having a ground fault relay that is sensitive enough to protect workers from potentially life-threatening electric shock or arc flash incidents.

Ground faults are unintended conductive paths from a high potential line to ground, allowing electrical currents to pass through sensitive equipment components, or through personnel who touch the equipment housing. In either case, the results can be devastating.

It is estimated that 90% of all ground faults occur slowly due to dust buildup, moisture ingress, vibration, cable chaffing, or chemical and corrosive vapors, which lead to earth-leakage or residual-current ground faults that escalate to high current levels. Typically, each year there are about 150 fires and explosions in commercial and industrial buildings caused by electrical grounding failures, with an average loss of more $575,000 per event. The worst of these are often dangerous arc flash events.

In an attempt to address this issue, Littelfuse, Inc. has introduced its RCD300M2 Differential Current Relay, designed to improve worker safety and protect equipment from dangerous electrical ground faults. The device provides highly sensitive protection while avoiding nuisance trips and unnecessary equipment shutdown.

The new ground fault relay also provides features for automated monitoring and control in power distribution panels, switchboard installations, municipal utilities, elevators, new construction sites, and similar applications.

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