Instruction Manual
Troubleshooting
LIQ-MAN-245
June 2017
Section 2: Troubleshooting
2.1
Troubleshooting
To check the toroids, recall the data obtained during the Calibration Verification Process
(see Section 1.6). With the sensor empty of process fluids (preferably also clean and dry),
reapply the resistance to the yellow Cal Loop wires in the junction box. The reading should be
20% of its original value.
To check the RTD, disconnect RTD leads of the interconnecting cable (PN 23909-00) and
measure the resistance across the white and one of the red RTD wire terminals in the junction
box. See Figure 1-4. The resistance value should be close to the applicable value shown in
Table 2-1.
Finally, check the sensor for open connections and short circuits. Be sure to disconnect the
cable (PN 23909-00) before checking. See Table 2-2 and Figure 2-1.
Table 2-1 Resistance Values for Pt 100 and Pt 1000 RTDs
Temperature
Resistance (Ohms)
(°C/°F)
Pt 100
Pt 1000
18 / 64.4
106.9
1069
19 / 66.2
107.3
1073
20 / 68.0
107.7
1077
21 / 69.8
108.1
1081
22 / 71.6
108.4
1084
23 / 73.4
108.9
1089
24 / 75.2
109.2
1092
25 / 77.0
109.6
1096
26 / 78.8
110.0
1100
27 / 80.6
110.4
1104
Table 2-2. Sensor Wire Resistance Values with Instrument Cable Disconnected
(instrument leads and gray wire connected to terminal block, see Figure 2-1)
Connection (wire or component connections)
Resistance
Each twisted pair, WHITE to GRAY
0.4 to 0.9 Ω
YELLOW to YELLOW
0.1 to 0.5 Ω
WHITE to WHITE
> 20 MΩ
RED to YELLOW
> 20 MΩ
RED to each WHITE
> 20 MΩ
YELLOW to each WHITE
> 20 MΩ
ALL except RED to housing EARTH screw
> 20 MΩ
RED to housing EARTH screw
0.1 to 0.5 Ω
Troubleshooting
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