Testing Current Clamps

First, there is no simple test that can be done with current clamps, and even more so flexible types, as they require special interfacing electronics to ensure the clamp is operating correctly. One cannot simply test with an ohmmeter, this will not show you anything. The only reliable method is using a Power Recorder (or MultiPoint with external CT option).

Couple up a Power Recorder and PC and invoke PAS or Scenario. Ensure the recorder is not in monitoring mode (if so, stop the monitoring). Select the 'scope' readings and use the 'current' screen for the test.

In the following tests remember to change the display from 'scope' to 'phasors' and back to 'scope' after any change of current clamp. This will ensure the recorder configures itself to the clamp now plugged into the front.

Plug in clamps on each channel and place them on a single conductor you know to be carrying current of at least 10% of the clamp range. Look at each channel and find one which is displaying current close to what is expected. Remove all other clamps and use the working clamp to test each channel on the recorder and that each channel displays approximately the same current. This way you will ensure it is not the recorder that requires repair.

Now use only one channel and test each clamp in this channel. This will verify that each clamp is working as well as ensuring the readings from each clamp are approximately the same value (small variations in the current on the conductor are likely so do not use this as a validation).

If there are any questions please email