Eaton’s patented Maintenance Mode: Arcflash Reduction Maintenance System ARMS

Maintenance accidents are the leading cause of arc flash incidents and related injuries. Circuit breakers equipped with Eaton’s Arcflash Reduction Maintenance System ^TM (ARMS) will extinguish an arc almost instantaneously. This greatly reduces arc flash energy and the risk of injury. In the event of an arc fault, this system ensures an accelerated shutdown in comparison to a standard short circuit release. ARMS can be activated automatically when a control room door or maintenance panel is open, providing service personnel the highest degree of safety.

ARMS uses a separate electronic trip circuit providing faster signal processing and interruption times than the standard ‘instantaneous’ protection. When enabled, the trip unit will trip the breaker with no intentional delay whenever the configured pickup level is exceeded. When enabled, the Maintenance Mode function operates regardless of the instantaneous settings. 

Figure: An activated ARMS function provides for faster triggering in case of overload. In our example, the fault current is 1000A. The ARMS maintenance mode will cause the breaker to trip in 20ms instead of 20s.

ARMS is optional on Power Xpert Releases PXR20 electronic trip units. This technology is intergrated in the IZMX series of air circuit breakers ACB's and is also available for the compact circuit breakers MCCB's of the new digital NZM series.