Electronics > Beginners
4 wire resistance measurement
Specmaster:
This is how your Kelvin leads should look like, a separate core from each banana plug runs through to the clip, 1 core to each half of the clip. The red clip has 2 red plugs and so on.
ArthurDent:
I bought a similar pair of kelvin clips to those shown above but the ones I found on Ebay that were closest to what I wanted had the wrong connectors at the DMM end. The ones I found did have 2 separate wires going to each clip which was correct but the HP DMM required banana plugs. I wanted it to be simple to just plug the leads in and have the wires in the correct position.
I replaced the 4 individual connectors the clip set came with and used two double banana plugs with one of the wires from the red clip going to the red double banana plug and the second wire from the red clip going to the black double banana plug. The black kelvin clip has one of its wires going to the red double banana plug and the second wire from the black clip going to the black double banana plug. This gives me the corrections I had shown in post #3. On my HP 3457A the 5-way posts for input have different spacing between horizontal posts than it does for the vertically aligned posts so the double banana plugs can only plug in the vertical post which have the correct 0.75" spacing.
The possible problem I see with the previous photo of clips using 4 individual banana plugs is that both plugs from the red clip are red and you actually want one lead to go to red on the meter and the second red plug to go to black on the meter to have the corrections correct. If I had that clip set I would switch 2 of the plugs so the colors made sense to me and minimized the chance of connecting the plugs incorrectly.
rherber1:
Replies #10 and #11 are both correct examples of Kelvin test leads.
The Kelvin leads I bought are https://www.ebay.com.au/itm/LCR-Meter-Test-Leads-Lead-Terminal-Kelvin-Clip-Wires-for-UT612-UT611/332008183641?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649
As we have discovered from the UT612 teardown thread the internal photos of the UT612 clearly show that the inner guard sockets are connected directly to the ground plane and as such this meter is not capable of using Kelvin leads.
https://www.eevblog.com/forum/testgear/review-and-tear-down-of-uni-t-ut612-lcr-meter/msg199378/#msg199378
cowasaki:
--- Quote from: Specmaster on August 08, 2018, 12:17:16 pm ---This is how your Kelvin leads should look like, a separate core from each banana plug runs through to the clip, 1 core to each half of the clip. The red clip has 2 red plugs and so on.
--- End quote ---
Yes, that’s what I expected to see. They’ve sent me a second pair which are the same as the first so I’m going to rewire one pair to four banana plugs and one pair to the Philips din plug standard.
cowasaki:
Now to find some good quality banana plugs! I need quite a few as I need four for my PT100 probe as well.
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