Zhejiang University DCS temperature card issue
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It’s the clip for the thermistor in Zhejiang University No.1 Central Control System; I’ve forgotten the model. Each connection terminal has three wires, labeled A, B, and C. I measured the voltage today; I didn’t remove the wires at first, and A and B seemed to be around 2.x volts. Later, I removed the wire and measured the voltages of A and B; the voltage kept dropping, almost reaching 0. The same was true when measuring the voltages of B and C. The voltages of A and C remained unchanged, staying at 5 volts. What’s going on here? I think it would be more convenient to measure the voltage when maintaining thermistors; once you know the voltage, can’t you tell whether the wire is in good condition or not? I heard that a measurement circuit is some kind of bridge – what exactly is that? Please ask an expert to answer
Measure the resistance directly for AB, AC, and BC; by subtracting the wire resistance from the maximum resistance, the temperature can be determined. If the wire is broken, its resistance is very high.
I’d need to check with the control center for this estimate; the hardware manual doesn’t provide that level of detail. In fact, it’s better to measure the resistance of the thermal resistor in order to determine whether the temperature indication is correct – this is also the standard approach.
Should the resistance value signal go directly to the card module, or is a safety barrier added in between?