Measuring Systems

1. Sensitivity Registered Calibration

Sensitivity is calibrated by entering to the measuring instrument (such as a conditioner), the rated output, rated capacity and calibration factor, all of which are stated in Test Data Sheet attached to each transducer. If the transducer has TEDS installed and the measuring instrument is TEDS-compatible, sensitivity is calibrated by reading TEDS in which the same data as stated in Test Data Sheet is written.
Sensitivity registered calibration is conveniently used for digital measuring instruments with built-in AD converter and CPU.

2. Calibration by CAL Button

Sensitivity is calibrated by applying a load corresponding to the rated output through a press of the CAL button. This method is used for analog measuring instruments equipped with a CAL button.

3. Actual Load Calibration

Sensitivity is calibrated by applying a known load to the transducer that is connected to the measuring instrument.
To calibrate load cells with force or mass, “well calibrated weights” are used. This ensures most accurate calibration of load cells.

4. Strain Generator-based Calibration

In place of the transducer, a reference strain generator is connected to the measuring instrument. The strain generator applies to the measuring instrument a “strain” quantity corresponding to the rated output of the transducer.
When performing calibration, the following effects should be taken into consideration.

Cable Effect

When the distance between the transducer and measuring instrument is long, a relay cable may be used. In such a case, cable resistance affects measurement.
In “Sensitivity Registered Calibration” or “Calibration by CAL Button,” the effect should be compensated through calculation based on the sensor’s input resistance and cable resistance.

“Actual Load Calibration” or “Strain Generator-based Calibration” is made involving cable resistance and sensitivity (or CAL button) accuracy of the measuring instrument, thereby enabling calibration without receiving any effects of cable resistance and instrument’s sensitivity accuracy.

Parallel Connection Effect

Transducers are often connected in parallel. While transducers connected in parallel may be regarded as a single composite transducer, the resistance decreases to 1/number of transducers connected in parallel.
Thus, the output signal is affected in reverse proportion to the ratio of resistance decrease, thereby lowing accuracy.

The composite rated output of parallel transducers is calculated by averaging. Practically, however, the rated output varies between each transducer, thereby causing errors.
“Actual Load Calibration” is made involving such errors, thereby enabling accurate calibration.