LV MCCB/Contactor Insulation Resistance Testing 2

[nightfox1925]

Hello all. I would like to request in this forumn typical connection diagram for megger testing 600V MCCBs or contactors using 500Vdc megger.I do not have any connection diagram for this and any reference and links is appreciated from concerned tes professionals here.

Thank you.

 

[nightfox1925]

I have gone further and read some articles on this. The insulation resistance for a breaker are being done as follows:

1. Phase-to-Phase (each phase pair combination at line
side and load side separately, CB is open)

2. Phase-to-Ground (each phase and ground at line side
and load side separately, CB is open).

3. Across Each Phase With CB Open (IR measured across the
open contact of each phase separately).

However, I came across another test procedure that states that the test done with one phase and the other phases shorted to ground and interconnected to the megger "earth" terminal.

Which IR test connection is correct, this one or the above (1,2 & 3) connection?

 

[unclebob]

Nightfox,

for low voltage power circuit breaker 3 tests should be done:

Phase to phase (A-B, B-C and C-A), breaker closed.
Phase to ground (A-G, B-G and C-G), breaker closed.
Across each phase (A-A', B-B' and C-C'), breaker open (of course )

 

[Zogzog]

Yep, and should be done at 1000VDC for 60 seconds and should be >100M