Load Cell Troubleshooting
With placements in numerous industries and every type of environment, load cells undergo challenges that may impair their functionality. Some common causes of load cell malfunction include:
- Overloading scale capacity, which results in shock and load cell deformation
- Lightning strikes or electrical surges
- Chemical or moisture ingress
- Improper handling
Symptoms of load cell malfunction might be zero drift, the inability to calibrate and reset the scale, unreliable readings or weights that don’t register. After checking for obvious causes of load cell failure, such as worn cables, loose wire fittings or visible damage to the load cell itself, you can perform a series of signal measurements. Resistance measuring is most commonly applied to troubleshoot failing load cells. However, it will not expose all the information needed to cost-effectively repair a bad load cell. Below is a list of tests that can be used with one another to fully understand the problem.
Millivolt Return
Checking the millivolt return involves using your voltmeter to measure the voltage across the plus and minus signal lines.
Resistance Readings
Checking resistance involves taking a series of resistance readings with your voltmeter for each load cell. This can help determine if there is a fault in the internal load cell circuitry.
Leakage Test
This test involves using a megohmmeter and twisting all the wires together. One lead will attach to the bundle of wires, and the other will attach to the load cell body. The reading is expected to go off the meter. If the lights on the meter stay in range, it indicates leakage or perhaps water ingress.
