A 1472, A1579 Leakage current clamp
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4.1.3 Leakage currents in fault conditions
Faults in electrical installations and equipment can cause additional
continuous or
short-lasting leakage currents. Typical faults that can cause increased
leakage currents are:
Deterioration of insulation (because of pollution, moisture,
corrosion). This is causing a gradual increase of the resistive
leakage current,
Faults in electronic equipment.
If the neutral and PE wiring are connected together anywhere in the
installation this can result in an improper current distribution
through the neutral and PE conductors.
Typical faults that usually results in a high fault current that will immediately
trip the protective devices are:
Misswiring like changing the N and PE conductors.
Breakdown of insulation between active parts and earth anywhere
in installation or equipment
Short-lasting leakage currents are often a result of:
A sudden change in the voltage or current between active parts
and PE. This can result in a short leakage currents from several us
up to 100ms . Lightning and switching on/ off large loads can cause
such changes.
Fig.2: Fault leakage currents in electrical installations
