2391 question.

[La Poste]

Hello people.
I am studying my 2391 and have a question.
I can't seem to find the answer to it anywhere.
It is:

List in the correct sequence the first three tests to be carried out on a new circuit supplying a three phase kiln.

Guidance note three is great at listing tests for single phase and all my other books have plenty of single phase test explanations but I am finding it hard to get good information on three phase testing.
Can anyone recommend a book for me?
Or maybe a few links to good threads.
Thanks.

 

[IQ Electrical]

Hello people.
I am studying my 2391 and have a question.
I can't seem to find the answer to it anywhere.
It is:

List in the correct sequence the first three tests to be carried out on a new circuit supplying a three phase kiln.

Guidance note three is great at listing tests for single phase and all my other books have plenty of single phase test explanations but I am finding it hard to get good information on three phase testing.
Can anyone recommend a book for me?
Or maybe a few links to good threads.
Thanks.

Well, is there a specific test that is only carried out on a 3-phase circuit?

Where in the testing sequence does that test fall?

In other words, the sequence for single phase and 3-phase is identical until you reach phase rotation.

so your answer will be:

1 Continuity of protective conductors

2 Insulation resistance

3 Polarity

 

[james the spark]

sounds right to me if you like i have a quick reference sheet for the 2391 which i found very useful when i sat mine just send me a message if u want it.

 

[Sparky Ninja]

Well, is there a specific test that is only carried out on a 3-phase circuit?

Where in the testing sequence does that test fall?

In other words, the sequence for single phase and 3-phase is identical until you reach phase rotation.

so your answer will be:

1 Continuity of protective conductors

2 Insulation resistance

3 Polarity

I'd second that.

 

[La Poste]

Thank you people.
I am going through past exam papers as I think this is the best way to practice for the exam and also the best way to get things to stick in my memory.
I will no doubt have some more questions in the future so please be patient.
Thanks.

 

[IQ Electrical]

Well just post them up!

 

[La Poste]

Ok here's one that has been puzzling me.

State three different examples of a limitation that may be agreed with a client which is NOT already stated on the periodic inspection report.

And I know this one will be obvious to most of you but is the series of tests on a new radial circuit.
1. Continuity of CPC.
2. Insulation resistance.
3. Polarity.

And one more thing.
Why is it on page 103 of the OSG table 2D the maximum permissible measured earth fault loop impedance for an RCBO to BS EN 61009 such a low value.
I thought for RCBO's the earth fault loop impedance would be allowed to be very high, for 30ma RCBO 1667 Ohms.
I mean surely an RCBO behaves the same way as an RCD during an earth fault so how come these value are so high in this table.
The formula Z<50V/Ia springs to mind.

Thanks.

 

[IQ Electrical]

Limitations can be:The percentage of sampling.An item(s) of equipment that can not be isolated.No testing of luminaries over a certain height.Your sequence is correct and yes, you can use the 1667 Ohm maximum value as disconnection time is achieved by the RCD part of the device.

 

[La Poste]

So the table on page 103 OSG is misleading, no wonder I get confused!!

 

[savthespark]

Yeah,

Agree with posts. The 2391 is about understanding inspection and testing, single phase or three phase, fundamental principles. Happy revision.