3 phase testing

[basic]

3 phase testing

Well after nearly 9 months, I'm nearnly there to doing my AM1.

ooooooh, I hear you say. I know it is quite, quite exciting anyways the thing is...

I'm going to be doing a complete testing of a 3 phase circuit

We've never covered it in class to any great depth.

So doing an Insulation Resistance test, it would go as

Yellow Phase - Blue Phase Record result in 'M'Ω ohm
Yellow Blue Phases - Red Phase Record result in 'M'Ω ohm
Yellow Blue Red Phases - Nuetral Record result in 'M'Ω ohm

And is that it?

Please help just want to clarify it thats all

Thanks in advance

 

[Big_Spark]

As far as I can see you should make a complaint, you are being asked to carry out a task that you clearly have not been trained to do. The AM1 is crucuial to your advancement to thye next level, and you should be tested on what you have been taught, not what you have not.

That is a bloody Joke.

This is the very sad state of training today.

 

[basic]

Thanks for the reply, bt if I complained and being that the lecturer is also marking my AM1 paractical it may Not be a good idea to P*** HIM OFF.

Though, I will complain as soon as my course ends in June, to avoid difficulties.

Oh, by the way everything else in testing I am fine with, I just wanted to clarify the above. Is what I wrote correct?

 

[Big_Spark]

Basic, if you want to carry out an installation resistance test on 3 phase supplies then the correct procedure would be..

L1 to L2 = Result

L1 to L3 = Result

L1 to N = Result

L1 to CPC = Result

L2 to L3 = Result

L2 to N = Result

L2 to CPC= Result

L3 to N = Result

L3 to CPC = Result


Othere may do it slightly different, but if you wish to do it correctl;y then this is the correct way.

 

[basic]

Thanks I really appreciatte it

 

[andy]

Basic, if you want to carry out an installation resistance test on 3 phase supplies then the correct procedure would be..

L1 to L2 = Result

L1 to L3 = Result

L1 to N = Result

L1 to CPC = Result

L2 to L3 = Result

L2 to N = Result

L2 to CPC= Result

L3 to N = Result

L3 to CPC = Result


Othere may do it slightly different, but if you wish to do it correctl;y then this is the correct way.

i was told it was:

L1-L2
L1-L3
L2-L3
L1,2,3-N
L1,2,3-CPC
N-CPC

 

[Big_Spark]

Andrew, read my post, what was the last comment I made..it isn't in Chinese, but plain old English.

 

[andy]

Andrew, read my post, what was the last comment I made..it isn't in Chinese, but plain old English.

i was told to do it that way all the time as that was the recognised way

either way, youll still get the resulsts you need

 

[supersparks]

or you can just link out the 3 phases and test to earth and neutral, and between earth and neutral

if an unsatisfactory result is given then you test between each cable....

don't forget paralell resistance, will mean that your Rt will be lower than the lowest resistance recorded in an indervidual test

 

[Big_Spark]

Supersparks highlights the very reason for doing it properly in the first place.

 

[supersparks]

the above method is perfectly acceptable, if it passes on that your guarenteed all is ok.

if it fails on that then go into the full test sequence

 

[andy]

the above method is perfectly acceptable, if it passes on that your guarenteed all is ok.

if it fails on that then go into the full test sequence

you would have to test L1, L2 and L3 first tho before connecting L1, L2 and L3 together to test between L and N. which would be the way i said

 

[basic]

Would I have to do an Insulation Resistance test on each circuit on the 3 phase distribustion bourd or would the previous test be adequate.

I was previously told it would be. But after being ear-bashed by a guy off my course who says you have to do both! I thought I would check it out

thanks in advance

 

[Big_Spark]

Basic, all circuits on in any DB need to be individually tested and the results recorded, it is irrelevent whether those circuits are 3 phase fopr single phase.

 

[supersparks]

not true fwl, you may test an instalation as a whole.

if a low reading is recorded, you then go on to seperate the circuits up.

of course, this will, in large instalations, give lower over all readings due to paralell resistances. you will be measuring the Rt, if this passes then you know the whole instal is sound!

as for testing 3 phase systems, step by step:

join together all phases and test between them and neutral.

then test between phases.

or you can test between each of the live conductors in turn.

hope that is clear as mud