Pt100 thermal resistance two wire, three wire system and four wire connection effect on temperature measurement accuracy

1, Pt100 thermal resistance of three kinds of connection mode on the principle of different:

2 wire and 3 wire system are measured by bridge method, finally the relationship between temperature and the analog output value. Four wire bridge, not completely just using the constant current source to send, voltmeter measurement, measure the resistance value is given.

2, Pt100 thermal resistance of three kinds of connection mode's influence on measurement accuracy

connection wire resistance and contact resistance will have great influence on Pt100 platinum resistance temperature measurement accuracy, three platinum resistance wire or four wire connection mode can effectively eliminate the influence. Connected to the heat resistance test equipment ( Temperature controller, PLC input, etc. ) There are four terminals: +, I - I V, V +, - 。 Among them, the I +, I - Side is to provide thermal resistance with a constant current, V + and V - Is used to monitor heat resistance voltage change, test temperature change in turn. Please refer to the below:

( 1) Four wire system is from the thermal resistance on both ends of line 4, separate wiring circuit circuit and voltage measurement circuit wiring, high measuring accuracy, need to traverse. （ 2) Three wire system is raises three lines, Pt100B platinum resistance connection when the current loop and end and the reference voltage measurement circuits for a line ( I - namely the detection equipment Terminal and V - Terminal sub) 。 Precision is slightly better. （ 3) Two wire system makes the two lines, Pt100B platinum resistance connection when the current loop and voltage measurement circuit together ( I - namely the detection equipment Terminal and V - Terminal sub, I + terminal and V + sub sub) 。 Accuracy of measurement.