Pfc - pscc on 3 phase supplies

[driverman]

Hi, Guys,when measuring PFC-PSCC on 3 phase supplies,I know that you test between live conductors L1-L2, L1-L3, L2-L3 and then all 3 to Neutral and note lowest reading obtained. Then all 3 phases ( is that right term for C&G? ) to earth. Then neutral to earth and lowest reading obtained recorded Are these readings times x 2? Thanks. PS hardly ever worked on 3 phase.

ops think I'm getting mixed up with testing a 3 phase cable for IR

 

[Richard Burns]

You have described the IR testing.
For PSC you test L1-N, L2-N, L3-N take the highest reading and multiply by 2 to give the three phase PSC to record.
If, and only if, your meter can measure PSC on 400V would you be able to safely test the line to line short circuit current. This is not part of the recommended test procedure.

For PEFC you test L1-E, L2-E and L3-E and record the highest value.

The highest of the two recorded values (which will be the three phase value) is the PFC.

 

[driverman]

Once again, thanks Richard. Yes i realised I was getting mixed up. If doing a 3 phase Ze test lets say in a factory, what procedure would take place whist earthing conductor removed to test? Would the whole factory have to be shutdown?

 

[Brightspark2]

Once again, thanks Richard. Yes i realised I was getting mixed up. If doing a 3 phase Ze test lets say in a factory, what procedure would take place whist earthing conductor removed to test? Would the whole factory have to be shutdown?

You can't leave a system engerzied with the earth disconnected, so yes it has to be switched off/isolated. Arrange a time which is best for the client.

How ever most of the time in real life this isn't possible, a factory isn't going to shut down while you take a Ze measurement. So you take it with everything still connected and record it on your certificate and the reasons why.