Example: injection exclusion with two incoming feeders

You can use injection exclusion to monitor two incoming feeders.

Use of circuit breakers with normally open (NO) auxiliary contacts:

Use of circuit breakers with normally closed (NC) auxiliary contacts:

If	Then
D1 is closed and D2 is open	Both devices are active: Device No. 1 monitors the insulation of the system, Device No. 2 only monitors the insulation of transformer 2 connection as far as D2.
D1 is open and D2 is closed	Both devices are active: Device No. 1 monitors the insulation of the transformer 1 connection as far as D1. Device No. 2 monitors the insulation of the system.
D1 is closed and D2 is closed	Device No. 1 monitors the insulation of the system. Device No. 2 must be inhibited.

Then

Both devices are active:

Device No. 1 monitors the insulation of the system,
Device No. 2 only monitors the insulation of transformer 2 connection as far as D2.

Both devices are active:

Device No. 1 monitors the insulation of the transformer 1 connection as far as D1.
Device No. 2 monitors the insulation of the system.