3 phase testing

[Xcody]

I was just wondering if anyone would be able to help me with my question I have, it's about testing a 3 phase motor that has a contractor and overload, like I know that continuity and insulation resistance you would link out the contactor and overload but for the live tests I can't seem to see how you go about it? Like for a zs test? If there isn't a neutral at the socket for the motor how can you do a 3 lead test for zs and pfc? Thanks in advance if you can help, just an apprentice btw

 

[Darkwood]

Welcome to the forum Xcody

 

[Xcody]

Cheers have you got any advice you could offer me? Would be greatly appreciated

 

[Darkwood]

If your doing a Zs test you are effectively looking at the earth fault path(L-E) so N isn't needed, if your meter doesn't have a 2 wire option then connect N clip to earth as the meter is only using it as a ref' that you have a supply and isn't needed for the testing itself.
Test each phase to earth separately and note the worse reading.

 

[Xcody]

So when you're doing what you're saying have you linked out the contactor and overload or just pushed the contactor in? To close the circuit? I was thinking, see how zs=ze+(r1+r2)
could you use the r1+r2 given by the meter and the ze from the meter reading

 

[Simonslimline]

It would be (R1+R2)

r1 rn r2 refers to ring final circuit end to end values.

 

[Xcody]

R1+r2, you can get a meter value for that by linking out the contractor and overload (so it closes the circuit) and test from there, using the r1+r2 you get you could then add that on to the ze of the board it is feed from? No? So for example say you're r1+r2 for the motor circuit is 0.85 and Ze = 0.35, could you not using Zs=ze+(r1+r2) say 0.85+0.35 = 1.20 therefore the zs of the motor is 1.2 ohms?

 

[Simonslimline]

You have the upper and lower case mixed up. People will not know what you mean in terms of tests being carried out unless you use the correct terminology.

 

[Xcody]

R1+R2 in terms of R1+R2 method used when doing a continuity of cpc

 

[davesparks]

3 wire efli tests are intended for use only when it is impossible to use a proper high current test. So unless your motor is on an rcd you should be using a 2 wire high current efli test

 

[PEG]

Hi dude,your original question referred to the testing of a three phase motor...i presume you mean the fixed wiring testing,and not any tests performed on the actual motor.