One of the most important steps before starting any power quality analysis is proper selection of current clamps since they are the single most prominent (modifiable) factor influencing reliability and accuracy of measurements. Influencing factors pertaining to current clamps themselves are:

- Overall accuracy,

- Phase angle error,

- Current range,

- Whether they are used for AC or DC current measurements,

- Measurement environment.


Metrel power quality analyzers have accurate to a tenth of a percentage when it comes to current measurements, while most types of current clamps have accuracy that is measured in whole percentage points. Choosing the wrong type of current clamps for certain applications can have disastrous consequences for the quality of obtained measurements, making them unsuitable for serious troubleshooting and analysis.


There are two types of current clamps:

- iron clamps: A 1783, A 1391 PQA, A 1588, A 1636, A 1033, A 1281;

- flexible (flex) clamps, operating on the Rogowski coil principle: A 1501, A 1502, A 1503, A 1227, A 1227 SM, A 1445, A 1446, A 1582.

Both types have their advantages and disadvantages. Iron clamps are on average more accurate than flexible ones, while flexible clamps support larger current measurement range, from a few Amps to a few kAmps (up to 12 kA), and can be mounted on larger / more complex measured objects (measurement sensors up to 90 cm in length):

Following current clamps: A 1501, A 1502, A 1503, A 1227, A 1227 SM, A 1445, A 1446, A 1582, A 1281 and A 1588 are also so-called Smart current clamps, which support multiple measurement ranges and auto-range selection by the connected instrument for great accuracy. However, the use of auto-ranging feature is discouraged for detection of inrush currents and current transients in favor of fixed range selection prior to use.


For more detailed current clamps technical data see attached document below:


For A 1783 clamp technical data see attached document below: