User Manual

Description
2.3 Protection system
3WA Air Circuit Breakers
54 Equipment Manual, 05/2021, 92310000002-03
2.3.5.6 Ground-fault alarm
A ground fault can occur due to aging and the resulting deterioration of an insulating
component in a power distribution system or due to a foreign body in the system. If the fault
resistance is so high that the ground-fault current is below the settings of the ground-fault
protection, the electronic trip unit will not trip. With the ground-fault alarm, a high-resistance
ground fault can be detected without switching off the system. Then the elimination of the
fault must be initiated.
The ground-fault alarm detects fault currents between the conductors and grounded parts of
the power distribution system. It responds when the rms value of the ground-fault current
exceeds the set alarm threshold I
g alarm for the duration of the set delay tg alarm.
Characteristic