Level Pro ITC 450 User Manual page 15

ITC 450/470
User manual
Temperature sensor can be connected to the device in typical 4-wire circuit (Figure 4.17a) or 3-wire circuit
(Figure 4.17b). Due to precision of measurement 4-wire circuit is recommended.
If 2 wire circuit is used, the resistance of wires should be as small as possible, to avoid of measurement
errors. Measured value can be corrected (constant correction) using „toFS" parameter from menu
„inPt". Due to low precision 2-wire connection is not recommended.
When 4-wires or 2-wires connection is used, the resistance of particular wires (Ra ÷ Rd) CAN BE DIFFERENT.
When 3-wires connection is used, the resistance of particular wires (Ra ÷ Rd) MUST BE IDENTICAL to enable
proper compensation of it's resistance. The resistance of particular wire should not be greater than 20 .
a)
31 32 33 34
Ra
Ra, Rb, Rc, Rd can be different
b)
Ra
Rb Rc : Rd
RTD
Figure 4.17. Connection of RTD sensors:
a) 4-wires circuit; b) 3-wires circuit; c) 2-wires circuit
c)
31 32 33 34
n.c.
Rc : Rd
RTD
Ra, Rc can be different
Ra = Rc = Rd
31 32 33 34
n.c. n.c.
Ra Rc
RTD
www. levelprosales.com www. levelprosales.com
13