ABB PSTX Series Installation And Commissioning Manual page 48

2-wire measurement for PTC
When you use 2-wire temperature sensors, the sensor
resistance and the wire resistance are added. Correct
for the resulting systematic errors when you change the
tripping device. Use
to determine the temperature errors caused by the line
length. See Figure 5.24.
Tightening torques and cable dimensions.
Com 3
+(B) -(A)
23 24 25 26 27
5
Error caused by the line
The error caused by the line resistance is to
approximately 2.5 Kelvin/Ohm. If you don't know the
resistance of the line and you cannot measure it, you can
make an estimation of the error caused by the line with
this table.
Temperature errors in °C / K
The table below shows temperature errors, at an ambient
temperature of 20° C, for different line lengths and
conductor cross sections for PT100 sensors.
Table 1 Temperature errors in C°/K
Line length in m Wire size mm
10 1.8
25 4.5
50 9.0
75 13.6
18.1
100
39.3
200
91.6
500
48 Connection | Installation and commissioning manual |
Table 1 Temperature errors in C°/K
Temp In Analog out
T1 T2 T3 +24V + GND
28 29 30
2
0.50 0.75 1
1.2 0.9
3.0 2.3
6.0 4.5
9.0 6.8
12.1 9.0
24.2 18.1
60.8 45.5
Figure 5.24
PTC - 2 wire
M3
0,5 Nm
4,3 lb.in
1.5
0.6
1.5
3.0
4.5
6.0
12.1
30.2
1SFC132081M0201
Com 3 Temp In
+(B) -(A) T1 T2 T3
23 24 25 26 27
PTC - 2 wire
3,5 x 0,6 mm
(0.138 x 0.024 in)
Analog out
+24V + GND
28 29 30
AWG 12 ... 24
2
0,2 .. 2,5 mm
2
2x0,2 .. 1,5 mm
2
0,2 .. 2,5 mm
2
2x0,2 .. 1,5 mm