Confusion about 2394

[Nick81]

Hi all

I have the 2394 practical exam coming up and wanted a little advice on an issue.

Where the installation is split into two parts a three phase board, which supplies a single phase board. When completing the testing sequence should seperate them into db1 and it's test results and db2 and it's test results, or as the second dB is a circuit supplied from the three phase board treat is as a circuit.

My experience would say carry out all tests for dB 1 dead and live and then separately all tests for db2 dead and live, recording on separate sheets. Giving a ze for dB1 and ze for db2
And calculating the zs from this.

Has anyone who recently carried out the testing exam got any input on this, have the exam next week and would really appreciate any input.

Thanks

 

[DPG]

Separate sheet for sub DB. Zdb for sub board.

 

[Nick81]

Superstar thanks alot.

 

[Richard Burns]

Just remember that the supply to the second board is a distribution circuit from the first board and so should be recorded as one of the circuits on the first set of test results.
Thereafter the second board is a separate set of test results.

 

[The Ghost]

As far as I know Ze is at the point of origin only, not at sub main that would be Zdb.
Edit: Just realised Zdb has been mentioned

 

[The Ghost]

Strange though, is that what they told you would be part of the exam/practical. I remember doing various tests, and loads of fault finding on initial verification, about seven hours in all. Must be the new exam?...No that's the 2391 1/2

 

[Deleted member 26818]

Not sure about calculating Zs?

 

[Ian1981]

Not sure about calculating Zs?

It’s an acceptable method to calculate zs , the other being to directly measure it.
Both are acceptable methods regardless of opinion.
In the case of the Am2 tho I agree that I would measure it to show you know what you are doing

 

[SparkyChick]

A calculated Zs is acceptable if you know Ze or Zdb and R1+R2.

Beaten to it by @Ian1981

 

[Deleted member 26818]

It may well be acceptable to calculate Zs.
However it not acceptable to record calculated values on the schedule of test results.

 

[Phil Thompson]

All dead tests first. Results recorded on a separate sheet for each board.

Then live tests after, on both boards and again results recorded on the separate sheets.

 

[Ian1981]

It may well be acceptable to calculate Zs.
However it not acceptable to record calculated values on the schedule of test results.

Deleted

 

[Simonslimline]

Calculated versus directly measured Zs debate has been done on here many times.

Both are acceptable methods, except a calculated value will not highlight a high resistance through an OCPD/RCD etc.