differences testing between single and 3 phase?

[Mark8v]

Hi,

My name's Mark and I'm new to the forum - wanted to start by saying hello to everyone

Quick question I wanted to ask, I'm fairly comfortable testing single phase but I need to test 3 phase distribution board - is there much difference in the actual testing process?

Any help will be much appreciated!

Cheers,
Mark

 

[scotsparky]

No difference in basics at all really. Remeber to take a psc on all 3 phases and use highes, same as eli and use highest as well. Doing Insulation just do the L1-L2, L1-L3, L1-N ,L1-E, L2-L3, L2-N, L2-E, L3-N, L3-E

 

[Mark8v]

Thanks for the quick reply.

So for the pfc, testing at the main switch - instead of L and N for single phase - do you test the various 3 phase combinations instead there?

How about earth loop is that different or do you just test between main earth to L1 then L2 then L3?

Cheers,
Mark

 

[sparks1234]

Don't know if everyone else is the same but I have always been told to take your Ze reading on a 3-phase supply but then to double it.

 

[Guest123]

Easy Tiger!!! Dont put your tester accross the phases, you'll blow it to pieces!!!!

When testing PFC on 3 phase measure as you would single phase i.e L-E and L-N and take the highest of the two readings (PFC) and multiply by two for three phase.

Ze same as single phase, only difference being you do L1, L2, and L3 and record highest.

 

[sparks1234]

Easy Tiger!!! Dont put your tester accross the phases, you'll blow it to pieces!!!!

When testing PFC on 3 phase measure as you would single phase i.e L-E and L-N and take the highest of the two readings (PFC) and multiply by two for three phase.

Ze same as single phase, only difference being you do L1, L2, and L3 and record highest.

Sorry thats what I meant, fault current not Ze. minds gone blank as I have been dragged around Tesco all afternoon.

 

[Mark8v]

Thats great, thanks a lot for the advice!

Cheers,
Mark

 

[Guest123]

I will say though, if you're not sure what to do then dont do it as you dont get a second chance with 415V

 

[Mark8v]

Thats a v.good point, I'm only learning at college at the minute though so not let loose on the real world yet!

 

[trix]

If you are testing pfc with a Megger 1552 series, you will not blow up your meter.......
connnect green to one phase, and red to 2nd phase, the meter will tell you the voltage, then also the pfc,
repeat this to all phases ( red-yellow,,, red-blue,,, yellow-blue,,,) in old money. The highest reading is the one you are to record.