Electronic Calibration The process of electronic calibration
When it comes to calibration, the specific steps involved depend on the equipment being used. However, the basic process remains the same and consists of the same four basic activities.
The four basic activities of electronic calibration are:
- 1. choosing a standard to use,
- 2. a testing phase,
- 3. the calibration phase, and
- 4. the final reporting phase.
Choosing a standard to use for calibration
The very first step in calibrating a piece of electronic equipment is choosing a standard to use. There are several different standards that exist, from in-house standards created by certified calibration shops to international standards that are applied globally. This can sometimes cause confusion because a calibration engineer does not need to use these international standards for testing, but they do need to have measurements that can be traced back to them.
For example, standards that an individual calibration shop uses must align to secondary standards. These, in turn, must compare to primary standards, and these must correlate to international standards. Sometimes, individual "shop standards" may need to correlate to national standards depending on the country, but these will always meet international standards in most developed nations.
Calibration engineers will usually turn to the International System of Units, which consists of seven base units: the second, meter, kilogram, ampere, kelvin, mole, and candela. These are derived from natural quantities that do not change, such as the speed of light.
The testing phase
During the testing phase, a calibration engineer will test the electronics that need calibrating against a test sample. Depending on the equipment that needs calibrating and how it is used, a calibration engineer may choose one of many testing options.
Depending on the results exhibited during the testing phase, the calibration phase may or may not need to be carried out.
The calibration phase
There are many errors that can be corrected through calibration, two of the most common being span and zero errors.
A zero error is where the equipment does not measure correctly at the low end of its measurements closest to zero. For example, a set of electronic weighing scales may give a reading of 12 grams when there is nothing on the weighing plate. In this case, placing a 100-gram weight on the weighing plate, for instance, would return a reading of 112 grams. The calibration of a zero error involves adjusting the equipment so that the line of output runs in parallel to the line of correct measurement.