Is it necessary to install a temperature change cabinet in the central control room?

Personally I don't think it's necessary. Now there are integrated temperature transmitters, or thermocouple + temperature transmitter, and the 4-20mA signal is directly connected to the I/O card. There is no need to run compensation wires to the control room at all. However, I don’t know about the price. Could it be because of the price advantage? Let other heroes discuss this.

Temperature signals, especially in chemical plants involving explosion-proof areas, generally need to convert the temperature signal into a 4~20mA signal through a temperature transmitter and send it to the DCS. In addition, if equipped with an ESD system such as FCS, there is generally no separate temperature card, only a 4~20mA type input card.

This question should be considered when considering your system card selection. 1. If you choose PLC, there is no card directly connected to the resistance signal, and it must be converted into ma signal. 2 If you choose DCS, if the number of thermal resistance points is not too many, you can also do this just to reduce the types of cards. Or if the PCS7 system does not support RTD redundancy, you can only convert the mA signal first to achieve redundancy.

I think it still has something to do with the card of the selected system. At present, the temperature remote transmission used in the design and control of general projects uses a split temperature transmitter (with on-site instructions) to convert the mv signal into a 4~20mA standard signal and send it to the control room for centralized monitoring. Other temperature detection signals are directly introduced into the control room.

It should be considered according to different situations. Temperature transmitter placed in control room: It will facilitate future maintenance and repair and reduce the failure rate of the temperature transmitter. Temperature transmitter placed on site: It is conducive to the unification of cable specifications, reducing cable procurement costs and reducing the failure rate on the line.

Temperature change cabinets are still necessary, and some points that require redundancy are usually converted using temperature transmitters. Coke explained it very clearly. It is often encountered in projects, but it is debatable whether it should be an independent temperature change cabinet. I personally think it is not necessary and can be placed together with the card cabinet.

What if my system can provide rtd and tc cards? Is it necessary to install a transmitter in the control room? And all the temperature signals go into this cabinet, and it seems difficult for the temperature change card to carry the hart signal. This post was last edited by backhamm1982 on 2008-1-9 20:17 ]

In explosion-proof areas, ordinary RTDs and TCs without temperature transmitters can also achieve explosion-proof functions. Thermocouples and thermal resistors (without temperature change) are simple energy storage components and can be directly matched with safety barriers and intrinsically safe cables to form intrinsically safe measurement systems. There are often companies on the market under the guise of intrinsically safe thermocouples and thermal resistors (without temperature change), claiming that their products are intrinsically safe, which is superfluous. Temperature variation can simplify signal types, and as Coke said, some DCS cards do not support RTD and MV redundancy. In addition, regarding the choice of integrated temperature transmitter or centralized temperature transmitter (involving temperature change cabinet). In SH-3005 1999, 3.3.1, there is a sentence "If the design requirements are met, a temperature transmitter integrating measurement and transmission can be used." There seems to be no hard and fast rule on which type to choose. This post was last written by wen * da edited on 2008-1-9 23:44 ]

DCS has thermal resistor and thermocouple input cards, which can directly connect thermal resistors and thermocouples to DCS. If you want to install a temperature change cabinet, you can find a place with a better environment on site to install the temperature change cabinet.

There is no need. Now both on-site transmitters and control system cards can realize temperature signal conversion. If your unit wants to be uniform, it doesn't hurt to get a temperature change cabinet! The last thing I want to say to you is: The simpler the control system loop is, the better if it satisfies function d. Reason: Fewer fault points, one more cable connector means multiple fault points!

If intrinsic safety is required on site, then a temperature-variable isolation barrier is most suitable.

I don't think it's necessary. As long as you choose the appropriate thermal resistance and thermocouple clamps, and connect the field cables directly, it will be ok.

Haha, we are already in the control room, and we still need to change the temperature. I wonder who designed it!

If it is a new system, if the shielding is good and there is no complex and explosive dangerous environment on site, then you must not install it. One more environment and one more possibility of failure. If it is an old system, the lines are seriously aged, the line shielding ability is poor, and the on-site conditions are flammable and explosive, it is recommended!

I feel that the cost of the heating cabinet is too high. I can just add temperature compensation directly to the card.