3.3.32
Over Temperature Alarm
An over temperature alarm is generated when the unit is driven into current limit by a non-load re-
lated condition. The basis for this function is the hardware control circuit that limits the unit's output
current based on abnormally high temperature at the unit's heatsink. The units go into current limit
due to this condition. This occurs when the heatsink temperature reaches 100 degrees Celsius.
3.3.33
Over Temperature Shutdown
Unlike the over temperature alarm which gradually reduces output current due to a high tempera-
ture, this function shuts down the module due to a high internal ambient temperature. Abnormally
high ambient temperatures (above 70 degrees Celsius) can reduce the life of or damage the unit.
This control is equipped with hysteresis. When the ambient temperature has cooled by approxi-
mately ten degrees the unit will resume normal operation. The fan will not operate during the shut-
down condition.
The temperature sensor is constantly monitored to establish reliable operation. If an unrealistic
temperature is measured it is assumed that the sensor has failed. Sensor failure is indicated by the
alarm message on the front panel display. The fan is set to the high speed setting.
3.3.34
UPF Heatsink Over Temperature Alarm
In the RSM 48/50 UPF and RSM 24/100 UPF series, the unity power factor circuit is protected from
thermal runaway by a hardware circuit that folds back the output current about 50% in very abnor-
mal circumstances. The front panel will display the message UPF HI TEMP to indicate this abnor-
mal condition.
ARGUS TECHNOLOGIES
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