The PEM (Power Entry Module) provides the following features: redundancy, when a secondary PEM is installed, either the primary or secondary PEM can serve as the active PEM, if the active PEM fails, the standby PEM powers up and becomes active; a maximum of 1200 watts of -48VDC power to the Cisco 6160 backplane connector; system earth ground bond integrity; circuit breaker control handles, which are accessible from the front panel; circuit breaker auxiliary alarm contacts, which remotely signal the status of the tripped breaker; reverse polarity protection, and two internal cooling fans.