help with testing 3 phase motor circuit on 2391 practical

[Lucas123]

Hi guys,

Have 2391 practical tomorrow morning and the only thing im unsure on the 3 phase motor circuit not done a great deal on 3 phase testing

For R1 R2 do i take a reading for each line and neautral ?

do i disconnect from motor and just feed from db to there ? or commando socket outlet and link at motor ?

is it classed as vunerable equipment when it comes to IR test ? will 500v dc damage it ?

And Zs from cammando socket outlet with motor running ?

any help much appreciated

thanks in advance

 

[Lucas123]

Hi guys,

Have 2391 practical tomorrow morning and the only thing im unsure on the 3 phase motor circuit not done a great deal on 3 phase testing

For R1 R2 do i take a reading for each line and neautral ?

do i disconnect from motor and just feed from db to there ? or commando socket outlet and link at motor ?

is it classed as vunerable equipment when it comes to IR test ? will 500v dc damage it ?

And Zs from cammando socket outlet with motor running ?

any help much appreciated

thanks in advance

For R1 R2 do i take a reading for each line and neautral ?
( meant each line and cpc )

 

[pushrod]

When i did it the only Zs reading you had to take was from a socket - you could just calculate the rest. And we did IR testing at the tails making sure we had removed the one circuit with an rcbo first. The L1-cpc, L2-cpc, L3-cpc should all be the same anyway as we were repeatedly told "there are no faults on this board" even though there were!

 

[pushrod]

and if you are doing the small fault finding board look in the FCU (if there is one) and check the value of the fuse i remember that was where my last fault was - a 13A fuse to lighting!

 

[Lucas123]

funny you should say that i had a little practise run last week and pulled this because there was 2.5 coming in and 1.5 going out
i checked it and it was a 13A but my tutor didnt see it as one of the faults just the crossed polarity for the supply side

 

[ukylou]

hi mate do all testing as far as commando socket. Each phase seperate circuit, 3x R1+R2, 3xIR, 3xZE. Motor is not your resposibility unless stated at start of testing,

 

[WayneL]

As he took the exam two years ago this coming January, I'm pretty sure he's passed it by now......though you never know!!

 

[SirKit Breaker]

funny you should say that i had a little practise run last week and pulled this because there was 2.5 coming in and 1.5 going out
i checked it and it was a 13A but my tutor didnt see it as one of the faults just the crossed polarity for the supply side

He was correct. 1.5mm flex will take about 16a, the fuse is there to protect the flex, so 2.5 in and 1.5 out is fine. Your tutor wont see it as a fault,

1, because it isnt (have a look at the flex size of appliances fitted with 13a fuses).
2, City and Guilds give the spec for the test rigs, and the centre will be Externally Verified from time to time to make sure that these things are to the spec they require.

Cheers........Howard