2391 Practical exam

**Hammerspark** · 24-03-2009

I am at present trying to prepare myself for the 2391 practical exam but i am having problems working out the best way to do the R1 + R2 test for the Motor circuit. I realise this test will have to be done on both sides of the motor contactor but do you link between L1 to earth in the 3 phase board and take the reading at the motor contactor, then do the same for L2 & L3 or do you linlk L1,L2 & L3 to earth at the board. As you can probably tell im getting a bit bogged down with it, any help would be much appreciated as my cousre tutor was rubbish ! Any help on the Earth loop test for the same circuit would be good as well, Thanks.

**LlandrilloSpark** · 25-03-2009

Not sure if this helps?

I had to wire and test a 3 phase motor as part of my practical exam in my 2330
I put the link in the distribution board between L1 and E, disconected the Neutral from the DOL Starter, made sure the motor isolator was in the on position(if u have one), also the contacts of the DOL Starter held in and tested between L1 AND E at the motor itself.

I used a combination of 1.5mm singles and 4 core SWA, not sure if u have a similar set up, but i got a satisfactory R1+R2

Mike

**Hammerspark** · 26-03-2009

Originally Posted by LlandrilloSpark

Not sure if this helps?

I had to wire and test a 3 phase motor as part of my practical exam in my 2330
I put the link in the distribution board between L1 and E, disconected the Neutral from the DOL Starter, made sure the motor isolator was in the on position(if u have one), also the contacts of the DOL Starter held in and tested between L1 AND E at the motor itself.

I used a combination of 1.5mm singles and 4 core SWA, not sure if u have a similar set up, but i got a satisfactory R1+R2

Mike

LlandrilloSpark Thanks for the reply, i take it that you only needed to to test between L1 & E at the motor with the motor contactor held in and that was ok ? No need to repeat the same test for L2 & L3 ? have i understood you ok? The course tutor i had advised us to do an R2 test with the wandering lead but i've since found out that someone on the course has just failed because the examiner wanted to see the R1 + R2 test. How did you do the Earth loop test for the circuit ?

**kung** · 26-03-2009

Hi Hammerspark
Also remember on act to notify customer of power going off and switch off/lock off and put key in pocket ! i know it sounds minor but you will fail before testing if you dont.
Regards
Kung.

**LlandrilloSpark** · 26-03-2009

No need to test between E-L2 OR E-L3, god knows why the guy wants a R1 reading, the whole test is about the continuity of the cpc(earth), continuity of phase conductors only applies to ring circuits, all we are doing by using R1 is to give us a return path for the ohm meter to give a reading.

Also not sure about the safe isolatio procedure, yes kung is right if the supply is on and you are doing a periodic test, then u need to isolate safely before you test, but if its a pre-commisioned test then the circuit would not of been under load before.

We didnt do an Earth Loop Test!

Mike

**Hammerspark** · 27-03-2009

Originally Posted by kung

Hi Hammerspark
Also remember on act to notify customer of power going off and switch off/lock off and put key in pocket ! i know it sounds minor but you will fail before testing if you dont.
Regards
Kung.

kung Thanks fo advice on the isolation procedure, have you any views as regards the best way to carry out R1 + R2 test ? 3 phase dist board to motor contactor to 3 phase spocket outlet, as this is for my practical 2391 exam all this is on a board. Cheers.

**trebor** · 31-03-2009

Originally Posted by Hammerspark

I am at present trying to prepare myself for the 2391 practical exam but i am having problems working out the best way to do the R1 + R2 test for the Motor circuit. I realise this test will have to be done on both sides of the motor contactor but do you link between L1 to earth in the 3 phase board and take the reading at the motor contactor, then do the same for L2 & L3 or do you linlk L1,L2 & L3 to earth at the board. As you can probably tell im getting a bit bogged down with it, any help would be much appreciated as my cousre tutor was rubbish ! Any help on the Earth loop test for the same circuit would be good as well, Thanks.

The 2391 practical is a PIR and should be live when you start your assessment, you are required to test with a suitable method which means R2 readings are fine, the starter contactor can be held closed to measure R2, a bigger pitfall is the insulation test test where the starter coil is not taken out of circuit or the test is not carried out on the load side of the starter.
The most important and first box for the asessor to tick is the request for information drawings diagrams etc and asking permission to disconnect supply
The next box is for safe isolation and has accounted forall failures that I have assessed, isolate , lock off, put the key in your pocket, prove voltage tester, ten tests on 3 phase to prove dead and reprove voltage tester, this should be a smooth with no delay between proving tester,teting board and back to proving the tester, place safety sign ie electrician working, hope this helps