Sensor: Thermocouple , Pt100 or mV
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.
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.
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.
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
current goes to the upper limit (>20mA)
Output current goes to the lower limit (<4mA)
Correction: is a parameter to calibrate the offset of transmitter output.
You can correct small measurement errors by changing this parameter.
For grounded thermocouple, it is recommended to use isolated transmitter
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.
transmitters supersedes EMC standards EN 50081-2, EN 50082-2, for industrial environments.
They are very robust for both conducted and irradiated interferences.