Nortel DMS-100 Series Maintenance Manual page 82

2-62 Star Remote System hardware
Temperature sensing
The SRMO cabinet is provided with over temperature protection to prevent
component damage in case of overheating.
There are three thermostats in the SRMO cabinet:
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In the SMRO, when the temperature drops below 70° C (or 65° C in the
SRME), the converters are turned ON without manual intervention.
There are four resistive temperature sensors in the RLD cabinet. The sensors
are scanned by the SMC card to check the temperature is within the -30° C to
70° Χ. If the temperature exceeds 50° C, two fans are activated to cool the air
in the cabinet. When the temperature decreases to 30° C, the fans are
deactivated. If the temperature goes below -10° C, the right fan is activated at
low speed to circulate warm air generated by electronic components. If the
battery compartment temperature goes below 0° C, the battery compartment
is activated. The heater is turned OFF when the battery compartment
temperature is above 5° C. These sensors are located as follows:
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An additional temperature sensor is located in the battery compartment that
connects to the rectifier to regulate its output voltage.
Circulation fans
The SRMO cabinet is provided with two dc-powered, 90 mm circulation fans.
The SMC card controls the fans in the TSS. These fans have two operating
modes.
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To keep the cabinet cool, the cabinet has a closed air circulation. Air is pulled
through the TSS cage by the circulation fans and routed up to flow along the
external metal walls of the cabinet. This allows the transfer of heat through the
walls to the outside environment. These two fans are controlled by the SMC
card in the TSS. If a fan fails, a fan alarm is generated.
297-8353-550 Standard 05.01 March 2001
If the temperature at the top of the cabinet exceeds 80° C, a thermostat at
the top of the SMC card turns off the NTTR72AA power supply and
ringing card. This action switches OFF the TSS while the ac power is on.
one thermostat at the top of the SRMO cabinet that controls the TSS heater.
one thermostat at the ACP card that controls the battery compartment
heater.
one at the top of the cabinet in the LMU card
one at the bottom of the cabinet on the dc panel
one in the battery compartment
cooling mode, when both fans are operational
heating mode, when one fan runs at a reduced voltage to reduce its speed