2391 practical DOL starter

[La Poste]

Greetings all.

I am trying to get a few things straight in my head before Tuesday.
The main thing I am not sure about is this three phase motor starter.
The way I was gong to tackle it was to R1+R2 it.

Starting at the DB link L1 -E, get examiner to hold contactor and measure at the socket and record.
Then link L2-E and do the same, then link L3-E and do the same, record the highest value.
Add value to the measured Ze and compare results to tables in BS7671 to see if EFLI values are
low enough to comply.
Any comments welcome

The thing I am not sure about is IR testing the board as a whole in one hit with the DOL starter attached.
Is the DOL starter vulnerable to IR testing at 500V?
I have read quite a few posts and can't seem to get a straight answer.
I understand that the starter must be tested in two halves, one half from the board to the starter
and the other half from the three phase socket end to the starter but do we need to actually take the wires out of the DOL starter before IR testing?
Can we put 500V across the terminals of the DOL starter without damaging it?

This DOL starter is the only thing I am really not sure about and any advice would be appreciated.
Thanks.

 

[trev]

The examiner will not hold the contactor in mate. I was told (and did it this way and passed) to measure from DB to contactor then from contactor to socket, add the two measurements together and thats the (R1+R2)
Similarly with the IR for that part of the test rig test to the contactor then away from it.

 

[Guest123]

The examiner will not hold the contactor in mate. I was told (and did it this way and passed) to measure from DB to contactor then from contactor to socket, add the two measurements together and thats the (R1+R2)
Similarly with the IR for that part of the test rig test to the contactor then away from it.

Agreed. Your examiner wont be holding anything in for you.

Break it down into 2 steps.

 

[La Poste]

Similarly with the IR for that part of the test rig test to the contactor then away from it.

So it's OK to put 500V across this starter on the IR test?

 

[La Poste]

Just had an idea how to speed up the DOL test.

Why not do an R2 test on the CPC, and also an R2 test on L1, L2, L3 then add together line and CPC to give you R1+R2.
You could connect one end of the long lead to the socket and the other to the board and then press the DOL in manually.
That would save a load of time joining line and CPC at the board and measuring one half of the circuit up to the DOL and then having to join line and CPC at the socket and having to measure the second half of the circuit from the socket to the DOL.

I just wonder what the assessor will think of this method.

 

[Deleted member 26818]

Would you use such a method in real life?

 

[La Poste]

I asked the assessor before the test and he said the preferred method was to R1+R2 in two halves and then add them both together but he also said only do one line, don't bother about the other two which I think is wrong.

Anyway I passed just about.

What I also think is wrong is the two hour time limit.
If you really want to do it properly and check disconnection times for each circuit, terminations and everything then two hours is not enough.

I don't know what to think but I passed that's the main thing and now I'm away on the ----.

Cheers all.

 

[Richard Burns]

Well done on the pass!
The time limit is there just make sure you know what you are doign and not muddling through blindly, you get faster with practice. And the main thing outside is get it done now! Unfortunately.

 

[La Poste]

Yeah it was a funny old test.

12 faults, insulation resistance fault, EFLI fault and a PIR.

I hope the 2391 is worth something after it suddenly changes number to a new exam.

It's a good exam.

It really tests you, it really tested me to the limit.

 

[Thomas123]

Yeah it was a funny old test.

12 faults, insulation resistance fault, EFLI fault and a PIR.

I hope the 2391 is worth something after it suddenly changes number to a new exam.

It's a good exam.

It really tests you, it really tested me to the limit.

hopefully it'll be worth even more

 

[Guest123]

Congrats L.P.:rolleyes4:

 

[silver surfer]

Well done L A Poste.

 

[Big n Daft]

hopefully it'll be worth even more

Not a chance!!!
History says that the "new" qual will be the bees knees, even if its pants.

 

[La Poste]

Not a chance!!!
History says that the "new" qual will be the bees knees, even if its pants.

I wonder if employers get fed up with it.
The numbers keep changing I mean.

I was lucky on the 2391 the examiner was helpful, he made a lot of allowances for exam nerves.
And the DOL had three little home made sockets for your testing probes to fit in just nicely.
Making it much easier than trying to crocodile clip on a socket.

He said at the beginning the board has no faults but I found three.
The biggest one was he said it was TN-S and when I IR'd neutral to earth I got zero ohms.
I was taking neutrals out of the board and re-testing and wasted 20 minutes with him trying to figure it out and then he said
Ahhh and pulled the main plug to the board out of the mains, even though it was switched off with a rotary switch
the supply to the switch is TNC-S and hence no reading between neutral and earth.
So there were a few cock ups on his side.
The biggest issue was time though.
It's a hell of a race to get it all done in two hours.

 

[BicMac]

The biggest one was he said it was TN-S and when I IR'd neutral to earth I got zero ohms.

Lucky he didn't pick up on the Incoming earth not being disconnected?

 

[SouthernSpark]

Lucky he didn't pick up on the Incoming earth not being disconnected?

Should it be disconnected for an IR test?

 

[wams]

Hi all,

Im also doing my 2391 course starting on 12th March. Ive been studying since christmas with GN3, BS7671, OSG and the exam success book. Ive had no practical experience so may be ive bitten off more than I can chew, I got £300 to spend from the local council and didn't know what course to spend it on, so I choose this one.

I have spent the last couple of days writing a practical program using extracts from the web and the books highlighted above etc. i will upload as an attachment for you to look at and comment (once again critiscm welcome). Please advise if ive perhaps worded the program wrong, missed any critical information and so on.

Many Thanks

Wams

 

[brucelee]

good luck mate i was in same position had never tested a 3 phase board before with the preperation you put in you should be ok as i did the same studying month after month 12 hrs a day

Hope all goes well for ya