Problems with multi-core cables for thermoresistors and thermocouples
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Multiple thermocouples without transmitters, transmitted using multiple pairs of compensation cables； Multiple thermal resistors are supplied without transmitters, and transmission is achieved using multiple sets of three-core computer cables. Have everyone used these two approaches?
Thermocouples need to be transmitted using their dedicated compensation wires, which function as an extension of the thermocouple...
Thermistors have a wide range of applications. However, the compensation wires for multiple pairs of thermocouples may not be suitable, as different calibration numbers require different compensation wires, not to mention whether their lengths are the same. Of course, multi-point thermocouples like those used in synthesis towers are feasible; first, they have the same calibration rating, and second, their lengths are the same as well (through a junction box).
May I ask: Is it feasible to transmit multiple thermistors through a junction box using a multi-core cable (such as ZR-DJYPVP 8×3×1.5)? Will there be any interference?
This post was last edited by Gongsun Yang on 2016-2-17 at 20:29. If it’s a split-screen layout with a master screen, the problem isn’t too serious. Currently, field temperature transmitters offer good performance and are inexpensive. Except in very few cases where rapid response is required, thermocouple and thermal resistance signals are generally not transmitted to the control room. I don’t understand why the people upstairs insist on this approach. For thermocouples, the thermoelectric properties of the compensation wire being different from those of the thermocouple itself can affect the measurements.
No problem; thermal resistors do not interfere with each other. But stay away from power cords or electrical wires, as these are the sources of interference.
What the original poster mentioned – transmitting thermocouple and thermal resistor signals directly to the control room – is a very common practice.
That’s how petrochemical plants are used.
This situation can generally be understood as transmitting the thermocouple resistance signals from the field directly to the cabinet; this approach works without any problems. By using compensation wires, the error (in terms of control accuracy) can be essentially ignored. The thermoresistors are transmitted to the control room via cables, and our company uses shielded instrument cables with a diameter of 3*1.5 mm (the model is likely KVVRP). Even when the cable length exceeds 100 meters, there are no issues with its use.