3 phase PIR

[NoSparks]

I'ts several years since I did my 2391 which was the last time I did a 3 phase PIR. Can somebody remind me:
a) on nominal voltage should it be 230 or 400?
b) For Ze do I enter the highest Ze or the lowest? (0.09, 0.11, 0.13)
c) any other points to look out for?

 

[Guest123]

Hi there.

A) Nominal Voltage between Phases (U) = 400, Nominal Voltage to Earth (Uo) = 230.

B) Ze = highest reading.

PFC should be measured and then doubled for 3P as the highest fault will be between phases (unless you have a tester that can measure bewteen phases).

 

[NoSparks]

Yes a) of course!

but b) the lower Ze would lead to a higher PFC and which I immagined was what we wanted to get to?

 

[Guest123]

Well I agree a lower Ze/s is better in terms of achieving disconnection times, but the highest loop impedance is always recorded as a worst case scenario to ensure our upstream devices will disconnect in the required time.

 

[ian.settle1]

I would record the higher reading for Ze but note the higher PFC from the lowest Ze.