Types of clamp meters

Types of clamp meters

There are two types of clamp meter: instruments designed to measure load current and instruments designed to measure leakage current. The former can be further subdivided as follows:

•    Models designed to measure AC current with frequency band characteristics that are centered on commercial power supply frequencies
•    Models designed to measure DC current as well as AC current at frequencies at and below commercial power supply frequencies from devices such as general-purpose inverters

Clamp meters can also be classified on the basis of the rectification method they use (either mean-value rectification or RMS rectification).

Rectification methods of clamp meters

There are two methods for converting current into true RMS values: the true RMS method (true RMS value indication) and the mean method (mean rectification RMS value indication).

Although both methods yield the same value for undistorted sine waves, distortion of the waveform causes the values to diverge.

Most current measurement applications involve measurement of a current waveform that is not a perfect sine wave (i.e., they require measuring a current waveform that is distorted). If you wish to view results in the form of true RMS values, it is recommended to use a true RMS clamp meter.