flukey

Hi shakey,
i said that at the time but was told part of the test is to ensure you choose the correct meter and select the correct setting??
when i said that whether they were my meters or the centres was irrelevant because i was choosing the meter and the setting and if it was wrong then quite rightly i would instantly fail.
i was told that this was a non negotiable c&g rule which seemed a bit unfair at the time but is a distant memory now seeing as i passed anyway

charlie

Have got my practical soon can anybody help.
Have been told there is a 3 phase starter + socket, is it o.k. to measure R2 for continuity of c.p.c. and when Zs is required to measure ( by using a plug and lead ) it at the socket ??

Brutus

Hi Charlie

basically no - GN3 says that motor circuits (which this is) then the loop imepodence is ONLY measured at the supply side of isolated motor control gear.

Do R1+R2 checks on the three phase supply to the contactor, and again on the other side to the socket.

Then either calculate Zs = Ze + (R1+R2)+(R1+R2)

or add the additional socket side R1+R2 to the measured Zs.

And rememebr, you ONLY have to measure Zs at the socket outlets, C&G state for all other points, measure or calculate.

charlie

Understand what you are saying but thought that applied for the dangers involved with testing on a live moving motor as the test rig as a socket and therefore danger as been reduced to a minimum i would have thought this to be o.k.

Brutus

well the reasons are many, not least because the motor O/L contacts add a fair bit of resistance, however GN 3 says it pretty much as i have said it, therefore thats the way it is done during the test, and thats the way C&G mark it as well - I have been doing it all day!!

charlie

What marking 2391 all day ??
If so you obviosly know what you are talking about and i will have to have a rethink on my approach to my exam.

Any other help /advice would be appreciated.