Impact of Pt100 thermal resistance two-wire, three-wire and four-wire wiring on temperature measurement accuracy - News - Global IC Trade Starts Here Free Join

1. The three wiring methods of Pt100 thermal resistance are different in principle:
The two-wire system and the three-wire system are measured by the bridge method, and finally the relationship between the temperature value and the analog output value is given. Four-wire bridge is not entirely except that constant current source transmission, measured voltage, measuring the resistance value is given.
2. Influence of three wiring methods of Pt100 thermal resistance on measurement accuracy
The resistance and contact resistance of the connecting wires can have a great influence on the temperature measurement accuracy of the Pt100 platinum resistor. The three-wire or four-wire wiring method of the platinum resistor can effectively eliminate this effect. The test equipment (temperature controller, plc input, etc.) connected to the thermal resistor has four terminals: I+, I-, V+, V-. Among them, the I+ and I- terminals are used to supply a constant current to the thermal resistor, and V+ and V- are used to monitor the voltage change of the thermal resistance, and sequentially detect the temperature change. (Source: http://) Please refer to the picture below:

(1) The four-wire system draws 4 wires from both ends of the thermal resistor. When the wiring is connected, the circuit loop and the voltage measurement loop are separately and separately connected. The measurement accuracy is high and many wires are required. (2) The three-wire system is to lead out the three-wire. When the Pt100B platinum resistance is wired, the reference of the current loop and the voltage measurement loop are referenced to one line (ie, the I-terminal and V-terminal of the detection device are short-circuited). The accuracy is slightly better. (3) The two-wire system will lead to the two wires. When the Pt100B platinum resistance is wired, the current loop and the voltage measuring circuit are combined into one (ie, the I-terminal and V-terminal of the detecting device are short-circuited, the I+ terminal and the V+ are short-circuited. Short). Poor measurement accuracy.