TEMPERATURE TRANSMITTERS - NON- ISOLATED OR ISOLATED, HEAD MOUNT OR DIN RAIL

4-20mA OUTPUT OR 0-10Vdc OUTPUT

Input Sensor: Thermocouple , Pt100 or mV

Measuring range: values define the temperature limits for the transmitter. If the measured temperature is equal to the lower range value, the transmitter output will be 4mA, and if the measured temperature is equal to the upper range value, the transmitter output will be 20mA. If the temperature is in between the range values, the transmitter output will be proportionally changed from 4 to 20mA.

Example for the 4-20mA output temperature transmitter: If you set the range values to 0 and 120C, you will get 4mA when temperature is 0C and 20mA when temperature is 120C.

Example for the 0-10Vdc output temperature transmitter: If you set the range values to 0 and 120C, you will get 0V when temperature is 0C and 10V when temperature is 120C.

Sensor Failure Detection: specifies the action that will be taken by the transmitter when a failure (opened thermocouple, opened or shorted Pt100) is detected in the temperature sensors.

Upscale: Output current goes to the upper limit (>20mA)

Downscale: Output current goes to the lower limit (<4mA)

Zero Correction: is a parameter to calibrate the offset of transmitter output. You can correct small measurement errors by changing this parameter.

Note: For grounded thermocouple, it is recommended to use isolated transmitter

Many people use grounded thermocouples with non-isolated transmitters. In a grounded thermocouple the sensor element is in electrical contact with its protection tube (to improve thermal response time). If the protection tube is in electrical contact with the entire system and the system is not completely isolated or is not properly grounded, some electrical noise (or voltage) will be conducted to the input terminals of the transmitter. Since the transmitter is not isolated, the same electrical noise (voltage) will be present in the output wires. This noise or voltage may cause noise or damage in the measurement of the measuring instrument that reads the 4-20mA transmitter wires.
The decision between isolated and non-isolated transmitters is highly system dependent. You have to consider the whole installation, required safe margin and cost.

All transmitters supersedes EMC standards EN 50081-2, EN 50082-2, for industrial environments. They are very robust for both conducted and irradiated interferences.