There are many users that want to know fault finding tips. So here, you will find a simple yet very useful fault finding the guide for load cell system. Read on and get informed!
Some of the common faults to strain gauge load cell
- Gives erratic output display especially when the load is removed or applied.
- The weighing scale gives incorrect or overloads reading for the known weight or it may not give any kind of reading at all.
- Sudden or quick change in zero balance value of load cell.
- Random changes and unstable readings in zero balance point of a load cell.
Checking bridge integrity
It can be done when weighing scale tends to read overload or incorrect readings for the known weights. It includes measuring input resistance, output resistance, and bridge balance.
- Firstly, disconnect load cell from measuring devices or junction box.
- After that, measure output and input resistance across the output and input terminals with the help of an ohmmeter.
- These values can then be compared with the ones in a datasheet.
- Bridge balance is acquired by comparing resistance from negative output lead to negative input lead with resistance from negative output lead to the positive input. Difference between readings is usually meant to be at least 1.
The changes in measured value can be caused by failures in an electrical component or even by an internal short circuit. The internal short circuit can result from excess temperature, lightning strikes, or physical damages.
Shock resistance tests
It is carried out if load cell provides erratic output display when the load is either applied or removed. The following is its procedure.
- Connect load to a stable voltage source.
- Connect the voltmeter to an output terminal.
- Tap on load cell gently with a small mallet to shock it mildly. Just make sure to prevent from overloading load cell.
When it is checked, readings must not be erratic. They must be stable and return to zero points.
After evaluating the load cell modules in the above-mentioned ways, you can get to know the cause of the fault. However, if the issue cannot be fixed, then you may consider replacing the load cell.