Stuck on mock exam question.....

[bilbo_88]

I tried answering this question but am having difficulty, was wondering if anyone could help me out...


At the termination of an MI cable, which test range should be used for a 230 volt circuit. What result should be expected?

 

[bilbo_88]

its an insulation resistance test

 

[cdavies33]

I'm guessing insulation resistance at 500volt and the reading should be > 200M or that depends on which tester you use. The answer could also be >1M as that the lowest acceptable value in BS7671

 

[High Tower]

Ir test/500v Line to outer sheath, Neuteral to outer sheath and Line to neuteral. you are looking for a minimum reading of 1Mohm but ideally a minimum of 2Mohm

 

[Guest123]

Insulation resistance test @ 500V with a minimum acceptable reading of 1Mohm.

 

[bilbo_88]

so 1.0 is the as lowest.....the higher the number gets the worse the reading is?

 

[telectrix]

not o IR test the hbigher the resisance the better. remember, if you reasd the last posts, you are measuring the resistance between L/N and E. the ideal reading would be infinity as the inly connection between these is the mineral insulation. you are doing the test to determine 1. if the insulation has got damp. 2. you have not ballsed up and shorted out the conductors when you terminated it. end of lesson.

 

[High Tower]

so 1.0 is the as lowest.....the higher the number gets the worse the reading is?

You meed to get this right mate, its not 1.0 its 1Mohm as in 1 mega ohm !!

So 999 ohms would be a fail.

If a Pyro has been terminated correctly and depending on what machine you use to test you should expect something like

>200Mohm

that means "overange" so its is a figure greater than the tester can measure and >200Mohm means Greater than 200 mega ohms

 

[ian.settle1]

so 1.0 is the as lowest.....the higher the number gets the worse the reading is?

With this quote your not coming within a mile of my house

 

[High Tower]

With this quote your not coming within a mile of my house

Lol

I think he has the Jist now

 

[big dave]

1M ohm =1Mega ohm=1Million ohms .......IR test bigger is better

I'm still training too...get yourself a copy of the unite handbook for testing (the yellow one) its only 7 quid it is a really useful book

 

[simpson93]

ir test is to ensure the circuit has no dead shorts in it or low ohm faults normally you will get a reading of >999 or whatever the highest reading is however anything more or equal to 1
altho if you get anything between 1-2 you will need to investigate further.

 

[Phil]

so 1.0 is the as lowest.....the higher the number gets the worse the reading is?

you might be mixing the higher / lower values up with continuity testing using a (low resistance ohm meter) when you are testing insulation resistance as said the value is healthy when high. when testing continuity the value would want to be a low one in (ohms)