Behaviour under conditions of arcing due to an internal fault
A failure inside the switchgear will cause an internal arc. This arc burns between the faulty phases or to earthed parts of the switchgear.
During the test very high pressure will occur within the substation. Due to the arc hot gases will leak from the switchgear. For the personal safety of the user internal arcing tests are performed to verify the product safety. The following criteras have to be met during the test (corresponding IEC 62271-200):
Correctly secured doors and covers do not open
No fragmentation of the enclosure occurs and projections of small parts more than an individual mass of 60 g are not accepted
Arcing does not cause holes in the accessible sides of the switchgear
The indicators do not ignite due to the effect of hot gases
The enclosure of the switchgear remains connected to its earthing point.