Checking The Load Cells - Siemens SIWAREX WL200 Series Operating Instructions Manual

Error messages and troubleshooting

8.4 Checking the load cells

8.4 Checking the load cells
NOTICE
Damaging of load cells
Do not use an Ohmmeter to measure resistances that feeds a higher voltage into the load
cell than is permitted in the specifications.
Locate and check faulty load cells
1. Locate the possibly faulty load cell by checking the individual load cells under load, corner
load or by disconnecting the individual load cells.
2. To check a load cell for a defect, you must measure the following values:
– Zero signal
– Insulation resistance
– Input and output resistance
– Jumper resistance
The procedure for measuring the individual values is described below.
Measure the zero signal
1. Completely remove the load from the load cell to be checked.
2. Disconnect all the load cells.
3. Supply the load cell to be checked with approximately 10 V DC. Use the weighing module
or an external power supply for this purpose.
4. Measure the voltage between SIG+ and SIG-.
5. Divide the measured voltage by the supply voltage.
The result must correspond to the value in the data sheet.
Measure the insulation resistance
1. Disconnect the load cell.
2. Connect all cables together.
3. Measure the insulation resistance between the cables and the load cell housing.
4. Measure the insulation resistance between the cables and the cable shield.
5. The following measurement is only possible when the shield is not connected to the load
cell housing.
Measure the insulation resistance between the cable shield and the load cell housing.
The insulation resistance must correspond to the value specified in the specifications.
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Operating Instructions, 07/2016, A5E02199611B-03
SIWAREX WL200