amp probe Question

[COLDLAVA]

is there a process of amping parallel feeders, using the standard amp probe or is the a device on the market for that purpose?(standard amp probe can only close around one 500mcm at a time)

 

[bth0mas20]

If both 500mcm's are equal length, and originate and terminate at the same points then you only need to get the amprobe around one cable. Then multiply the amperage by 2. That is your total.

 

[brian john]

There are large CT's available that work with your clamp on.

Flexible CT's

Addition works well if the loads do not change drastically from any moment in time. Probably more reliable than multiplication.

 

[frenchelectrican]

I know there is a gimzo that called current transformer link or cable it wrap around the conducter but just becarefull with the ratings.

but right now i just can't find the manufacter make that but i know there is a thing out there but if someone who know this item i am talking about please chime in on this one

Merci, Marc

 

[mdshunk]

Do you think the one in the bottom center would do the trick?

photo by Brian John

 

[quogueelectric]

Upon review of the picture

Upon review of the picture

I see your megger is not in the bag you must be happily meggering something.

 

[mdshunk]

I see your megger is not in the bag you must be happily meggering something.

Not my picture. That's some of Brian John's stuff. I stole the pic, cause I'm cool like that. I did put a picture credit under it, though.

 

[bill addiss]

http://www.amprobe.com/cgi-bin/pdc/viewprod.cgi?pid=22&tid=1&type=elec

http://www.amprobe.com/cgi-bin/pdc/viewprod.cgi?pid=1422&tid=1&type=elec

 

[frenchelectrican]

Thanks Bill for the link on that one

Merci, Marc

 

[COLDLAVA]

thankx from Coldlava

thankx from Coldlava

thank you all for your replies to my question, this will be very helpful to me. louds like the company has to buy some more tools.:smile:

 

[don_resqcapt19]

Brandon,

If both 500mcm's are equal length, and originate and terminate at the same points then you only need to get the amprobe around one cable.

You really need to check both conductors. Small changes in the impedance of one can makes substantial current differences. A number of things can change the impedance even when the conductors are the same length and use the same termination method.

 

[ptonsparky]

Change the colors on that lower Amprobe & it looks like my Fluke. Wonder who makes for whom.

 

[bill addiss]

Change the colors on that lower Amprobe & it looks like my Fluke. Wonder who makes for whom.

Fluke and Amprobe are related now. Either Fluke, (or the company that owns Fluke) acquired Amprobe last year.

Bill

 

[Lxnxjxhx]

amp probe question

amp probe question

I don't see why you can't probe each line and add the measured currents. Current probes have "insertion impedance" which acts like a small inductor in series with the line you're measuring, but I'd think it'd be negligible (you could check this with an application engineer from the meter manufacturer).

For example, http://www.lecroy.com/tm/products/Probes/Current/Current_probes_datasheet.pdf

 

[brian john]

You can measure each conductor and add them, this was stated, BUT there is room for error in this method, just from changing loads.

The best method for accurate readings would be all conductors centered in a properly held CT. Of course this is not always possible. And the question is how accurate do you need, for KWHR revenue metering it had better be as accurate as possible. For spot checking loads, one should realize there are field errors.

We have taken 3 separate Clamp on amp meters all recently calibrated and get different readings.

 

[Lxnxjxhx]

amp probe Question

Don't know what happened to my first reply. Here is a better one.
Get two similar current probes. Measure the current on one conductor while clamping the second probe on the same conductor. If the reading on the first probe drops significantly, then the insertion impedance of the probes is too high for this application.
If the reading is unaffected, unclamp the second probe and measure the current in each conductor with the first probe and total the readings.

 

[ptonsparky]

We have taken 3 separate Clamp on amp meters all recently calibrated and get different readings.

That really makes me want to spend the money on calibration.

 

[brian john]

All my equipment is calibrated regularly, many jobs will not accept reports without cal verification and should the case end up in court cal can be critical. The errors are due to acceptable errors in the meter accuracy, placement on the conductor, ect...

 

[Lxnxjxhx]

amp probe Question

Correction: Fluke says

We don't specify insertion impedance. Given the range, frequency
response and accuracy of the Fluke 30 (and our other clampmeters),
insertion impedance is not significant.