LEVEL 3 -Assignment Help for 3 faults - FIRST FAULT RING CONTINUITY

[Foxhound]

Hello there,

I'm currently taking my Level 3 and have been given an assignment to do which I have all most finished but I was wondering if anyone could use their infinite electrical knowledge and help me out with 3 faults that I need to identify and rectify? I will lay out below what I have so far written out and if anyone can point me in the right direction ill be well chuffed. Thanks

Ring 4 - On testing the ring where all the conductors are the same size they test (Note that this all the information available)

E1 and E2 = 2 Ohms

N1 and N2 = 2000 Ohms

L1 and L2 = 2 Ohms

The Fault

Now my first inclination is to say Open circuit on the Neutral because as we know from the question that all the conductors are the same size. An Open circuit situation would mean there is a break in the continuity of the circuit producing a an increased risk of an overload else were in the subset of the ring but could it also point out just a high resistance at one of the terminals? Or indeed more than one break in the neutral?

To Rectify the Fault.

Now I have idea how I would go about this but its is just trying to articulate it in away that doesnt take up the

Guys I had the answer written out for you lot to check but some reason the website only saved the top portion of my thread as it signed me out

Any ideas id appreciate it thanks

 

[Guest111]

2000 ohms is more likely to be a high resistance connection than a break,if it was a break the reading would be infinity, to locate the fault you would split the ring at the midpoint and measure the resistance of the faulty leg back to the board,this could be done using either the long lead method or connecting to another cable at the cu and dividing the resistance,EG connect e1 and n1 at board now at midpoint the resistance should be approx 2 ohms, then connect e2 and n2 at board and measure on the other set of cables at the midpoint, on the faulty side you will get the high resistance.Then split at next socket and test again and so on until the fault clears,when this happens the fault is in the cable between the point you are at and the previous point. hope this makes sense,sometimes its easier to show than explain.

 

[Foxhound]

Thanks mate, your right it is a lot easier to show than explain.

If it is high resistance couldn't I do a insulation resistance test around the broken ring leg. N to N at each end of the Twin & Earth it make sure whether it is absolutely an open circuit or high resistance?
And could this mean double checking my Live and Earth reading, maybe the cable length as there may be a dodgy join?

 

[Foxhound]

Wouldn't the reading depend on your meter? A low resistance Ohmmeter is set to 0-20 ohms. Might pick it up as O/R?

I could just write down for both and that way I'm covered for both i supposed, as it could be two different faults.

 

[telectrix]

no to the IR tests. continuity on each half of the RFC, then halve it again till you find the high res. connection. could be loose terminal or screw clamped on insulation.

 

[Foxhound]

Thanks mate, your right it is a lot easier to show than explain.

If it is high resistance couldn't I do a insulation resistance test around the broken ring leg. N to N at each end of the Twin & Earth it make sure whether it is absolutely an open circuit or high resistance?
And could this mean double checking my Live and Earth reading, maybe the cable length as there maybe a dodgy join?

 

[Golden_Boy]

Its a continuity issue , Nothing to do with IR. Think about it... You are testing from the ends of what is in essence a single peice of cable. It should read the same as the other legs UNLESS there is a continuity issue!!!!

 

[chrish_1977]

Because there is a poor connection, this is causing the high reading, the ir wouldn't show that up, because if I remember right with ir you are checking the condition of the insulation and that there are no conductors touching, a poor connection will give a high reading as everyone had said before, an open circuit won't show a connection at all no matter what leg you test ( please correct me if I'm wrong, find it easier to talk the answer rather than type it out)

Also if you use a low reading ohmmeter and the range is set too low you should always start at the highest range and work down through the settings, that way you are checking your meter is set correctly too

 

[Foxhound]

Because there is a poor connection, this is causing the high reading, the ir wouldn't show that up, because if I remember right with ir you are checking the condition of the insulation and that there are no conductors touching, a poor connection will give a high reading as everyone had said before, an open circuit won't show a connection at all no matter what leg you test ( please correct me if I'm wrong, find it easier to talk the answer rather than type it out)

Also if you use a low reading ohmmeter and the range is set too low you should always start at the highest range and work down through the settings, that way you are checking your meter is set correctly too

Thanks for the reply,

I'm a bit confuse now,the guy who first replied said it was more of high resistance problem than a break. A break means an open circuit which is a break in the continuity of the ring. A high resistance would me a poor join , termination etc. An insulation resistance test should tell me if it is an open circuit or high resistance. If I compare my live and earth continuity readings and calculate the approx length from the OSG I can check both the existing continuity reading are approx right, if one has a higher resistance it should indicate a poor joint?

Urgg confused !!

 

[Silly Sausage]

An IR test measures the resistance between 2 or more electrically separate conductors.
For a new cable this would be >> several 100s of ohms.

In your case, you're trying to find a break/poor connection in a single conductor.
So, continuity test is friend here.

 

[telectrix]

your 2000ohms is telling you it;s high res. not a break.

 

[Foxhound]

An IR test measures the resistance between 2 or more electrically separate conductors.
For a new cable this would be >> several 100s of ohms.

In your case, you're trying to find a break/poor connection in a single conductor.
So, continuity test is friend here.

Thanks for the reply,

I've got 2000 ohms !! on the Neutral.

Does it depend on the meter? Only i thought you were suppose to test at o-20 ohms. If my reading is 2000 ohms it should read O/R shouldn't it? But on the question it states 2000 ohm.

So is the meter different? urrg someone tell me the difference from an open-circuit and high resistance reading I'm confused...I thought it was a continuity issue at first but the very first reply threw me out. HELP!!!

 

[Foxhound]

What harm would it do to do both? Might make me look more attractive:angel_smile:

 

[Foxhound]

your 2000ohms is telling you it;s high res. not a break.

Thanks for the reply,

Right I've banged my head against wall. I think you could be right. A break would get a reading because...the conductor is broke in half!!!. Because I'am getting a reading could suggest exposed conductor is in direct contact with something giving me the high reading.

I'm i right or still stupid?

 

[Silly Sausage]

Right...you're measuring the resistance of a single conductor from one end to the other.
In this case...
If you used an IR meter, it would almost certainly read zero and be mistaken as short circuit.
If you used a LoOhm meter, it would probably read out of range and be mistaken as open circuit.
If you used a regular DMM, it would 2000ohm.

All depends on the range of the instrument you're using.
The question doesn't specify which test instrument was used (it's irrelevant), just the value measured.