|Visual Inspection Lets Us Know Which Cell Is Damaged|
We have wasted countless hours trying to troubleshoot non working load cells. In an effort to provide better customer service and shorten our calibration lead time (most calibrations are performed in 5-7 business days) we have developed a process to troubleshoot non working load cells. This blog post is our way of trying to help others save countless hours trying to diagnose common problems. We call this the Morehouse 7 Step Process For Troubleshooting A Load Cell.
1. Visual inspection for noticeable damage
2. Power the system up and make sure all connections are made and verify that batteries have enough voltage and are installed
3. If everything is appears to be working, but the output does not make sense, check for mechanical issues. Some load cells have internal stops that may cause the output to plateau. Make sure any adapters threaded into the transducer are not bottoming out.
4. Check and make sure the leads (all wires) are properly connected to the load cell and meter.
Inspect the cable for breaks - With everything hooked up proceed to test the cable making a physical bend every foot
5. Check for continuity of the cable (pin each individual connection) – If the cable is common to the system, check another load cell and verify the other cell is working properly.
6. Use a load cell tester or another meter to check the zero resistance of the load cell – If you do not have a load cell tester you can check the bridge resistance with a common multi-meter
7. Check voltage and current on the power supply
|Inside Of An Overloaded Shear Web Load Cell|
A Morehouse load cell tester can be used to properly troubleshoot load cells
Video can be found here http://www.youtube.com/watch?v=zQNUpe2Bh5Y&feature=youtu.be
A Morehouse load cell tester can be used to test for the following:
Input and Output Resistance
Resistance difference between sense and excitation leads
Shield to Bridge
Body to Bridge
Shield to Body
Important: If the load cell has been overloaded, mechanical damage has been done that is not repairable. Overloading causes permanent deformation within the flexural element and gauges, which destroys the carefully balanced processing.
While it is possible to electrically re-zero a load cell following overload, it is not recommended because this does nothing to restore the affected performance parameters or the degradation to structural integrity.