Avaya Definity SI, Руководство по обслуживанию, Страница: 1111 / 2968

CABINET (Cabinet Sensors)
Issue 4 May 2002 10-325 555-233-123
Sensor S1 informs the Maintenance/Tape Processor, the Duplication Interface
circuit pack, or the EPN Maintenance circuit pack when the temperature at the top
of the cabinet reaches 65
0
C (149
0
F). Sensor S2 is not monitored by any circuit
pack. However, when the temperature at the top of the cabinet reaches 70
0
C
(158
0
F), this sensor causes the Power Distribution Unit to shut down power to the
entire cabinet. At this point, Emergency Transfer is invoked, and no other system
functions are provided.
The S3 and S4 sensors constantly report the temperature at the air exhaust in the
cabinet (top and bottom S3 sensors) and at the air intake (S4 sensors). The AHD1
circuit pack uses this information to determine fan speed and air flow alarm state.
If there is at least a 15
0
C (27
0
F) air temperature difference between the air
exhaust and air intake, and if the air exhaust temperature is greater than 50
0
C
(122
0
F), all the fans are turned up to high speed. If this condition exists, the
AHD1 circuit pack reports an air flow problem which results in a Minor alarm
against the Cabinet Sensors.
Variable Speed Fan Option. A variable speed fan is indicated by the Product
Code “ED67077 Gx,’ where x is 4 or a number greater than 4. A variable speed
fan contains Thermal Speed Control and an alarm circuit. As a result, the AHD1
circuit pack is not required in this type of fan.
A variable speed fan has two connectors: a two pin connector for the -48 volt input
power for backward compatibility, and the five pin Molex connector for speed
control and alarm circuitry. The -48 volt power circuitry is isolated from the speed
control and the alarm circuitry.
An alarm lead from all six variable speed fans is tied to a single lead leading to the
processor circuit pack. Three fans on the front of the system are connected to an
S3 sensor, which monitors the exhaust air temperature above carrier position “C.”
Three fans on the back of the system are connected to another S3 sensor, which
monitors the exhaust air in the power distribution unit. The speed of the variable
speed fans is determined by the temperature detected by the S3 sensors. Thus,
the fans’ speed changes continuously according to the temperature of the exhaust
air. If the fan speed drops below the preset limit, or if the fan fails, the fan alarm
circuit reports an air flow problem, which results in a minor alarm.
A multicarrier cabinet containing variable speed fans is presented in Figure 10-11
on page 10-326 . Note that the two S4 sensors that are included with non-variable
speed fans are not required with variable speed fans.
NOTE:
The new variable speed fans are backward compatible to the carriers for the
non-variable speed fans. However, the carriers for the variable speed fans
are not backward compatible to cabinets configured for the carriers for the
non-variable speed fans. Finally, the carriers for the non-variable speed fans
are not forward compatible to cabinets configured for the carriers for
variable speed fans.