The OTM cabinet requires 110V or 220V power supply. The temperature measurement and signal are used on a simple 4 to 20mA current loop. Refer to the system electrical drawing.

The sensor contains a sighting tube which has a lens and collects infrared radiation from a predefined target area. This radiation is transported onto an optical module with two detectors. The detector converts the incoming infrared radiation into a low-level electrical voltage which is proportional to the temperature of the target. The electrical voltages are then amplified, corrected, and fed to the equation to produce the temperature. This value is then linearized to produce an analog 4-20mA current output. There is an additional 4-20mA output provided which displays fault alarms and is to be used only for trouble shooting purposes by a qualified technician.

In normal operation the 4-20mA output is designed to stay within the ‘optimum range’. All the faults are displayed by 4mA in the signal output.