Cisco Systems Cisco 12008 manual Rotary Power Switch, Circuit Breaker Alarm Terminal Block

Overview of the Cisco 12008

Rotary Power Switch

The rotary power switch on the DC-input power supply performs the same functions as those described in the section entitled “Rotary Power Switch” on page 18 for the AC-input power supply.

Circuit Breaker Alarm Terminal Block

The onboard power supply circuit breaker actuated by the rotary power switch on the DC- input power supply incorporates an auxiliary switch that is mechanically linked to (but electrically isolated from) the power supply circuit breaker.

When the power supply circuit breaker is tripped by an overcurrent condition in the power supply, this auxiliary switch moves in unison, sending a signal to the circuit breaker alarm terminal block on the power supply faceplate (see Figure 1-7).

To remotely sense when the power supply circuit breaker has been tripped during an overcurrent condition, you can attach an external alarm-monitoring facility to the alarm terminal block. When the power supply circuit breaker is tripped, power is no longer delivered to the backplane and the router ceases to operate. Hence, if you have attached an external alarm monitoring facility to the alarm terminal block, site personnel can be instantly alerted to this serious fault condition.

Typically, an external alarm-monitoring system incorporates a light panel (visible alarm) or a klaxon (audible alarm) as the means for alerting site personnel to an alarm condition.

To reset the alarm contacts on the alarm terminal block, you must turn the rotary power switch on the power supply OFF and then ON again, much as you would reset any circuit breaker.

Note Any time you manually actuate the rotary power switch, such as when powering down the router, the contacts on the alarm terminal block remain unaffected. Hence, activation of the contacts on the alarm terminal block occurs only during a power supply overcurrent condition. In other words, these contacts are used to provide an immediate, overt indication of a power supply fault condition; they are not used to merely indicate that a circuit breaker has been turned off manually.

Product Overview 1-21