How many steps are required to connect the on-site thermal resistor to the DCS?

Thermal resistor, intermediate junction box, safety barrier. Thermal resistor, temperature variation, intermediate junction box, safety barrier.

Thermoresistors, cables, safety barriers, DCS

Thermal resistor – intermediate junction box – safety barrier – DCS card.

Thermal resistor - cable - safety barrier - clip

Thermal resistor, cable, intermediate junction box, cable, safety barrier, DCS

These days, DCS card modules usually come equipped with built-in temperature transmitters; therefore, the thermistor cable is connected directly to the module

1. Thermistor-cable-safety barrier (with thermistor transmission function)-AI card 2. Thermistor-cable-safety barrier-thermistor card 3. Thermistor-temperature sensor-cable-safety barrier-AI card. So far, only these three configurations have been seen; as for the intermediate junction box, it is optional……

There are countless methods; the original poster doesn’t know.

Since the failure rate increases with temperature changes for thermal resistors, and safety gates are easy to replace, in cases where it is not necessary to display the temperature on-site, thermal resistors can be connected via cables to the control room, from there to the safety gate, and then to the AI card. It is also possible to omit the safety gate and connect directly to the DCS temperature card. However, in terms of versatility, since DCS AI cards generally use 4-20mA input cards, it is better to use safety gates.

The thermoresistor (RTD signal; if it includes on-site temperature variation, it is a 4-20mA signal) is connected via cables – not necessarily through a junction box, as a single cable can be directly run to the cabinet room. In some projects, a terminal box is required, meaning that all signals from the field first go to the terminals before being distributed to various cards; however, this practice is generally avoided these days to save costs. From there, the signals proceed to the safety barrier and then to the cards. The type of card to be used is determined based on whether you have RTD signals or 4-20mA signals; generally, it is recommended that the output signal after passing through a safety barrier be 4-20mA. That is, if it has on-site temperature variation, it will directly become 4-20mA on site; otherwise, there is a signal converter at the safety barrier that converts it to 4-20mA.