Measurement error correction
I have a measurement error. What can I do?
There can be different reasons for measuring errors. If a measurement error occurs, the following possible causes should be checked first. If these sources of error can be excluded, please contact us.
- Higher friction forces by damaged roll bearings
- Friction by rotary connection or feed-through, e.g. with chill rolls
- Contact of the measuring roll with pressure rolls, strippers, or brushes
- Drives or brakes are connected to measuring roll
- Acceleration and deceleration forces acting at the measuring roll during speed changes
- Bending forces in the web when winding and unwinding
- The actual mounting position is different from the design
- Torque of mounting screws not according to specification
- Fixed and floating bearing not correctly mounted
- Liquids entered the cavities of the sensors
Why does my amplifier constantly indicate 4 mA or 0 V?
The current output constantly shows 4 mA:
• If a negative voltage is present at the voltage output, the zero point adjustment without measuring load must be carried out again.
The voltage output shows constantly 0V:
• Check the bridge supply voltage
- Short circuit due to sensor
- Amplifier defective
• Check amplifier input signal or sensor output signal
- Sensor is limited in the range of motion
- Measuring direction of the sensor does not point in the same direction as the actually acting force
- Sensor defect
Is my sensor defective?
• Connect the unloaded sensor to the amplifier and measure signal voltage
| - | Correct value: 0 mV |
| - | Values of up to +- 1 mV harmless |
| - | Values up to + 1.6x rated output signal: Sensor overloaded. May be used depending on the load direction |
| - | Values up to + -25 mV: Sensor overloaded. For amplifiers with zero-point adjustment, it may be possible to use them |
| - | Values greater than + -25 mV: sensor defective or incorrectly connected |
| - | Values at half bridge supply voltage: cable break or incorrectly connected |
• Input resistance and output resistance without amplifier
| - | Resistors should be approximately equal, with the input resistance being up to 1.5 times the output resistance |
| - | Typical output resistors are 350 Ohm, 700 Ohm, 1000 Ohm, 1400 Ohm and 2000 Ohm |
• Measure resistance between sensor housing and individual wires (insulation resistance) without amplifier
| - | The resistance must be greater than 10M Ohm |