Advice on Earth Leakage Clamp Meters

[RogertheBodger]

Hi Everybody,

Been looking to get an earth leakage clamp meter for some time, and I have been reading up on them on the forum.

After a thread last week Telectrix posted a link to an Ebay site for an Alphatec TEK 633. and I have since bought one, just got it and I must say It looks the Buisness for the money - so Thanks for the tip Tel!

In the instructions it shows the correct method of use is to clamp the cpc. and not to clamp the L&N to obtain an earth leakage reading - OK with that but the question is, on some posts members have shown these clamp meters being clamped around the live pair - and I,m OK with that but this must mean that there are two types of clamp meter out there?

If any of you who have one of these (types) could shed some light on this I would appreciate it.

 

[mechelec]

You cannot use any type of clamp meter (as far as i know) on the live and neutral together as it cancels out any current flowing through the clamp. If you are measuring earth leakage why would you want to ?

 

[malcolmsanford]

Hi Roger I got 3 of these for out here and I was more worried about the fact that the little booklet it comes with don't mention it does the protective current test, so I emailed Metrel and got this back from them

"Hello

As discussed in our telephone conversation earlier, the TEK633 is able to do an earth leakage test (please see below)

Set the TEK633 to AC and place around the earth.

Kind Regards



Metrel UK – Repair’s Technician"

I've removed the guys name Roger but that is what we do and have no problems


--

 

[RogertheBodger]

Thanks Malcolm.

I read your post on that and it was one of the deciding factors in the decision to get one,
I haven't used it in a combat situation yet but it's not always easy to get to the circuit cpc here. that is why I was asking about the option that some meters appear to have to clamp the live pair and obtain a Ma reading.

 

[malcolmsanford]

They are pretty good mate to be honest, they do everything that the tins says.

As an aside to this i'm suprised our forum sponsor don't sell these, they seem to do the AlphaTex 632 but not the 633, and with the amount of us guys recommending these, are they missing a trick.

 

[ExArmy]

wow, thats even cheaper than i have just bought it for. I paid £77.99 but they havent delivered it yet because of the delivery adress i put was different to the billing address, first thing monday i'm gonna tell them to keep it and buy the one from ebay!

 

[sparkydude]

POST REMOVED AND REPOSTED IN TESTING PROBS,

sorry did not mea to hijack this thread


Nick

 

[RogertheBodger]

Hi all , we have a situation on one of our current jobs with a substantial earth leakage , varies from 50A to 3300A the other day for a millisecond LoL, All cables are swa using the armour as cpc, in this scenario obviously we have some hefty cores to deal with and all are three phase. I doubt the meter above would be upto the job as the cables are upto 300mm 4 cores Anyone got a recommendation as to how we would go about tracking this down , bearing in mind we have approx 36 cables to test I was thinking we would need a meter with sepperate clamp cts to go round the cables to monitor it .

Any advice welcomed

Nick

You should really have started a separate thread with this Question.

 

[malcolmsanford]

That as got to be an earth fault rather than just a high protective current, what is connected to the supplies?

 

[RogertheBodger]

You cannot use any type of clamp meter (as far as i know) on the live and neutral together as it cancels out any current flowing through the clamp. If you are measuring earth leakage why would you want to ?

Thanks for the input Mechelec I know what you mean,
and I would agree with you but from other posts there seems to be an earth leakage clamp meter on the market that measures the earth leakage current by comparing the current flowing through the live pair and displaying the difference in Ma. and the why is that it is not always possible to access or identify the cpc (if the circuit has one!)

 

[sparkydude]

Removed my post and put it into the testing probs section., FYI the supplies are all sub mains to panels, MRI scanners general hospital supplies in general

Please post replies to the testing forum now

Nick

 

[RogertheBodger]

Thanks for that Sparkydude, appreciate it.

 

[pushrod]

If any of you who have one of these (types) could shed some light on this I would appreciate it.

Hi Rodger, i have an ELCM (bought from test-meter- model kew 2432) and you can use it either by clamping on a cpc or the line and neutral together. The second method works because if there is no leakage then L and N cancel and it gives a zero reading. If there is a leakage then it shows the difference. You can check it if you make a test lead - useful for checking appliances.
http://img.photobucket.com/albums/v509/snottie/P1020876abc.jpg

 

[RogertheBodger]

Hi Pushrod
I remember now that it was you, the picture you posted is the one I have seen in a previous thread, just couldn't remember where, or who posted it, The meter I have bought doesn't appear to have the function of reading the live pair but I won't know until I try it. and it is a feature that would be useful, maybe only top of the range meters have both functions?

Thanks for that.

 

[pushrod]

Hi Pushrod
I remember now that it was you, the picture you posted is the one I have seen in a previous thread, just couldn't remember where, or who posted it, The meter I have bought doesn't appear to have the function of reading the live pair but I won't know until I try it. and it is a feature that would be useful, maybe only top of the range meters have both functions?

Thanks for that.

Hi Roger, I would suspect that your meter will do both, but i guess you are right you only be certain when you have tried it. Computer equipment usually has a small amount of leakage, because of the filters, so might be worth checking on some. I think what distinguishes cheaper from more expensive meters are the ranges, sensitivity and frequency selectors. TBH mine has far more sensitivity (0.001mA) than i would ever have any use for. So could have saved myself some cash and bought a cheaper one.