Safety & Quality Standard

Electrical calibration refers to the process of verifying the performance of, or adjusting, any instrument that measures or tests electrical parameters. This discipline is usually referred to as dc and low frequency electrical metrology.  Principal parameters include voltage, current, resistance, inductance, capacitance, time and frequency.  Other parameters, including electrical power and phase, are also in this segment of metrology.  Ratio metric comparisons of similar parameters are often performed to compare a known parameter to an unknown similar parameter.

Electrical calibration involves the use of precise devices that evaluate the performance of key properties for other devices called units under test (UUTs).  Because these precise devices have thoroughly known performance characteristics compared to the UUT, performance evaluation and/or calibration adjustment of the UUT to identify or minimize errors is possible.  Typically, the performance of such precision devices should be four or more times better than the UUT. 

These precision devices fall into two broad categories. Electrical signal sources are often referred to as either calibrators or standards. Precision measurement devices are often classified as precision digital multimeters, measurement standards, or ratio bridges.

Calibrators and standards

A calibrator is usually able to provide a wide range of precision output signals, such as voltage settings ranging from as little as a few microvolts, increasing through several decades of millivolts, and volts, up to a common maximum of about one kilovolt

Additionally, modern calibrators commonly provide outputs for various different electrical functions (such as voltage, resistance, and current).

A standard is considered to be even more precise than a calibrator.  It is capable of performance that is about four or more times better than a calibrator.  But this improved performance is usually limited compared to a calibrator.  Often a standard can provide only one electrical function, and with only a single output setting, or a few output settings.

Precision digital multimeters, measurement standards, and ratio bridges

Precision digital multimeters (dmms) provide excellent measurement performance of various electrical parameters, through a number of decades of values.  Measurement functions usually include voltage, current, and resistance.  Less commonly, frequency, capacitance, and others can also be included.  The higher performance category of a measurement device is termed a measurement standard, or possibly even a measurement bridge.  These devices commonly have fewer functions but better performance than precision dmms.

For proper calibration, there are additional needs beyond only using precision devices to evaluate the UUT.  These precision devices must themselves be routinely calibrated in a manner which agrees with (or is traceable to) an international standard of the parameter being evaluated.  This is evidenced through an unbroken chain of documented comparisons with increasingly better standards.  Eventually this chain of compared standards includes a recognized national, international, or intrinsic standard.