Symptom |
Possible Cause |
Check |
Repairability |
High zero output |
- Sensor is under preload
- Sensor has been overloaded from too much load, off axis load, or moment.
- Sensor has experienced high cyclical load fatigue.
|
- Fixtures or bolting stress for causes of pre-load.
- Loading and support placement for off axis loads.
- Avoid excessive moments during installation.
|
- Overload shift would not be repairable.
- If zero offset is stable it may be possible to use sensor by use of Tare or subtracting zero from sequential readings.
|
Non-responsive zero output |
- Sensor or instrument is not powered.
- Sensor is not properly connected.
- Load is not displaced properly onto sensor.
- Sensor is not supported correctly and not allowing deflection to occur to measure load.
- Internal disconnect or short.
|
- Power and wiring to sensor and instrument.
- Sensor bridge resistance for possible opens or shorts.
- Perform continuity test on cable.
- Load is placed correctly on sensor loading surface.
- Sensor loading surface is not obstructed or supported and able to flex under load.
- Sensor support is not giving while sensor is loaded.
|
- Internal disconnections or shorts would not be available for repair.
- Sensor cable repair may be available if disconnect or short is not too close to sensor.
|
Non-responsive high output |
- Sensor is disconnected from instrument.
- An opening has occurred in sensor or cable connection.
- Sensor has been overloaded and deformed causing permanent high stress on internal gauges.
- Fixture, applied load, or mounting is causing a high pre-load on sensor.
|
- Power and wiring to sensor and instrument.
- Sensor bridge resistance for possible opens or shorts.
- Perform continuity check on cable.
- Sensor zero output to see if sensor returns to zero or has a high zero load output due to overloading.
- Remove load and loosen mounting bolts or fixtures to check if sensor is being preloaded.
|
- Overload shift would not be repairable.
- Internal disconnections or shorts would not be available for repair.
- Sensor cable repair may be available if disconnect or short is not too close to sensor.
|
Incorrect output for applied load |
- Load is not applied correctly to sensor loading surface or is off axis.
- Fixtures are not secure or obstruct loading.
- Sensor loading surface is not able to deflect with applied load.
- Sensor support is not ridged and firm.
- Incorrect sensor output is utilized.
|
- Placement of load on sensor.
- Fixtures are not impeding ability to load.
- Support surface is not giving with applied load.
- Calibration verified outputs are being used.
|
- Recalibration is available for confirmation of sensor performance.
|
Zero output drift |
- Unstable power supply, or noisy power supply, to sensor.
- Sensor exposed to temperature change.
- Sensor exposed to pre-load from fixture or mounting.
- Sensor exposed to liquid or humidity.
|
- Stability of power supply and noise levels.
- For temperature changes or unevenly distributed temperature changes.
- Possible loose fixtures and bolts
|
- Internal damage from liquid exposure is not repairable.
- Recalibration is available for confirmation of sensor performance.
|
Creep in output while under load |
- Load or fixtures are not stable.
- Power supply is unstable or noisy.
- Sensor is exposed to temperature change.
- Sensor support is not rigid and firm.
- Sensor exposed to liquid or humidity.
- Friction in assembly
|
- Stability of power supply and noise levels.
- Fixtures for stability.
- For temperature changes or unevenly distributed temperature changes.
- Confirm support surfaces are not giving while under load.
|
- Internal damage from liquid exposure is not repairable.
- Recalibration is available for confirmation of sensor performance.
|
Noisy or unstable output |
- Power supply is noisy.
- Load is not stable.
- Sensor or cable is placed close to high power equipment.
- Sensor or instrument is exposed to ground loop with other equipment grounds.
|
- Power supply stability.
- Load is stable and fixtures are secure.
- Reroute cables away from high power equipment.
- Confirm wiring and grounds are not connected to unintended equipment ground.
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- There are no active electronics in a load cell, such as capacitors or IC chips that may contribute to noise.
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