Fan Operation; Figure 7: Dc Power Leds - Alcatel-Lucent 7705 Installation Manual

Fan Operation

The 7705 SAR-F has five internal fans that provide cooling for the components. All five
fans are either on or off, depending on control signals from sensors monitoring the router's
internal temperature. Air enters from the intake vent on the right side of the chassis and exits
through the exhaust vent on the left side.
Individual fans are not user-replaceable; however, there is sufficient cooling even if one of
the fans fails. A minor alarm is raised when one fan fails. If two or more fans fail, a critical
alarm is raised and the 7705 SAR-F must be serviced.
Monitoring Temperature
7705 SAR-F Installation Guide
Ethernet Ports
1 3
Link Act Link
2 4
Link Act Link
By default, all the fans are turned off until they are turned on by system software. The
software controls the fans by monitoring temperature sensors, based on the following
criteria.
• Starting early in the system boot-up cycle, the internal system temperature sensor is
monitored continually. Fans are turned on when the internal system temperature
exceeds +104ºF (40ºC) and are turned off when the internal temperature drops
below +59ºF (15ºC). These thresholds correspond to an average external air ambient
temperature of +68ºF (20ºC) and +50ºF (10ºC), respectively.
• During normal operation, three sensors monitor the temperatures of critical internal
areas. The fans are turned on if any of these sensors indicate that the internal
temperature exceeds +131ºF (55ºC). Fans remain on until all of the internal sensors
indicate that the temperature is equal to or below +86ºF (30ºC). Also, an overheat
alarm is raised if any sensor temperature exceeds +183ºF (84ºC).

Figure 7: DC Power LEDs

Terminal block
5
Act Link Act
Link
7
Act
Link
8
+BattA -BattA +BattB -BattB
Act
BAT A
6
Act Link Act
-48V Batt
DC Power LEDs
7705 SAR-F Overview
BAT b
19852
Page 43