8820-A2-GZ48-00
January 2005
1
Replacement Fan Tray Assembly for the
8820 Broadband Loop Carrier
Model 8820-S3-900
Installation Instructions
Document Number 8820-A2-GZ48-00
January 2005
Fan Tray Assembly
The fan tray assembly is a dedicated cooling device installed in the chassis of the
8820 Broadband Loop Carrier (BLC) to provide forced–air cooling of the chassis.
The fans, located at the top of the BLC chassis, draw cooling air upwards from the
bottom of the chassis, through the circuit cards or card cage, forcing the air out the
opening, located at the top rear of the chassis.
The fan tray assembly consists of six fans, a metal bracket, and a printed wiring
board (PWB) with a press-fit connector and five status LEDs. Each fan provides a
sense wire that indicates the status of the fan. The sense wires are connected to
the backplane via the fan tray’s PWB and its connector.
The rated airflow is 900 cfm (based on 6 fans at 150 cfm each) at zero back
pressure.
The fan tray is powered by –48 or –60 VDC from the backplane of the 8820 BLC.
Nominal power consumption is less than 100 watts.
An LED is on the fan tray so that if a fan failure occurs, a signal is sent to the SCP
card or MCP card and the yellow Fan ALARM LED on the chassis lights. Removal
of the fan tray also causes the SCP card or MCP card to sense an alarm.
The fan tray assembly weighs 10 lbs (22 kg). It is secured by two fan-locking
brackets located on the right and left front of the assembly.
