The alarm circuit has voltage free relay contacts and are rated up to 2A @ 125V ac (RMS) load.
The internal supply to the relay is obtained from the transformer via a 20mm 1A fuse. These are connected to the Live and Neutral supply and therefore the relay and LED can only energise when there is an over-temperature condition or sensor fault, as long as the supply is present.
Over temperature protection
When a heatsink temperature of above 90ºC is detected by the sensor, the alarms relay changes state and the LED pulses rapidly. The power to the load will be disconnected and will not return until the temperature drops to 85ºC.
Temperature sensor loss
LED status changes to ON/OFF (fast pulsing) if the sensor fails.
The default setting of DIL switch (SW1) is in the ON position, the alarm relay will be energised under a fault condition. Changing SW1 to the off position will energise the alarm relay continuously until a fault condition occurs.
The unit will be factory set for an internal supply. If there is a requirement for the alarm relay and LED to energise when a phase fault condition occurs, then there is provision for an external 24V ac or dc supply.
NOTE – If the remote supply is utilised, the main (L1, L2 and L3) supply must come on before this supply is switched on.