Useful Information
Regarding Leakage Current Measurements
In practical applications, the insulation resistance test prescribed within the electricity safety regulations often presents a danger for electronic circuits (e.g. CNC, electronic control stations) in appliances, systems and machines, for the test voltage. On the other hand, this measurement may not be feasible for appliances or systems if they cannot be disconnected from the mains, for operational reasons.
Therefore, the differential current measurement is an extremely easy and sensible replacement measurement. Using a socalled leakage current clamp, e.g. UNITEST Leakage Current Clamp CHB 3, this measurement is fast and easy. For three-phase loads all active conductors L1, L2, L3, and N are surrounded. For single-phase loads both conductors L and N are surrounded.
The flowing leakage current is directly displayed on the leakage clamp display and does not require dangerous opening of the protective conductor (PE).
Considerable time is saved during appliance testing (e.g. washing machine) in compliance with DIN VDE 0701/0702, BGV A2 (VBG 4), if a leakage current clamp is used during operation to verify that the protective conductor (PE) current and the leakage current required are regarded.
If only the PE current is measured, leakage currents flowing via the water connection and via the washing machine capacity to the ground, falsify the measurement result. To avoid this incident, the washing machine would have to be positioned to ensure perfect insulation.
For leakage current measurements, all internal current circuits and control switch positions during operation are included.
If an error occurs within a distribution equipped with an RCD, e.g. a tripping of the RCD without apparent reason, the leakage current clamp is used for swift trouble shooting. Here, the leakage currents of the individual loads of the respective current circuit are measured. RCD tripping is often due to the sum of several leakage currents present at these loads and not caused by a faulty instrument.
Leakage current measurements using the UNITEST Leakage Current Clamps are a valuable support for every day trouble shooting.