The Fan Controller Cards; Operation; Alarm Indicator - Cisco VCO/4K Mechanical Assemblies

4.0 THE FAN CONTROLLER CARDS

The fan unit contains three controller cards located between the fans and the front panel,
inside the tray. Power is supplied to the fan unit from the VCO/4K's power backplane through
the plug located on the rear right side of the unit. Power goes onto the fan control cards through
the J5 connectors. Refer to Figure 5.

4.1 Operation

The fan unit operates whenever at least one power module is powered on. If no power modules
are on, or if the power connector is not plugged in, the fans do not run.
The power plug on the fan unit supplies power to the two fan control cards through the J5
connectors. The J1 and J2 connectors on the fan control cards supply power to the fans. Refer
to Figure 5.
Figure 5: Fan Unit - Internal Wiring and Pin Locations

4.2 Alarm Indicator

The fan control card monitors its own cooling fans. If current fails to flow through any of its
fans, the FAN ALARM LED is illuminated and a signal is sent to the AAC to trip MAJOR and
AUX1 alarms.
Fuse
The Fan controller cards
Fans
Fan
controller
cards
Fan Unit 1-5