Does a multi-conductor DC clamp meter exist? Possibly using hall effect sensors in a specific orientation?

I typically work with 24-28V DC solenoids valves & pressure transducers with 2 and 4-conductor configurations, respectively. The solenoid valves can have 50'+ of insulated 2-conductor SJOOW cable from where they are actuated using solid state relays to the valves themselves. Accessing the solid state relays can be a pain and actually fitting a clamp meter around the + excitation line is difficult. I'm trying to figure out a tool to easily measure if a DC circuit is powered or not. Ideally, this tool would be in a clamp meter configuration, where I can wrap it around any 2-conductor DC cable and be given some sort of audible confirmation that a load is present and even a rough current draw estimate (does not need to be accurate).

I know what I'm asking for seems impossible but I've referenced this previous forum several times now in regards to AC circuits and it gives me hope. Can single clamp measure total current from 3 wires?

An even more ideal feature would be if this clamp meter could also work on a 4-wire pressure transducer (+ Excitation, - Excitation, + Analog, - Analog). However I don't know how the hall sensors could be aligned for this application. Especially if the cable is shielded twisted 2-pair which we typically use (sounds even more impossible).

Any input is appreciated!

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    \$\begingroup\$ The answer is no. The physics doesn't allow for it other than to find the net current flow amongst all the wires. \$\endgroup\$ – DKNguyen Dec 15 '19 at 19:04
  • \$\begingroup\$ Clamp is a loose concept. If it's populated with so many sensors that the space vector structure of the field is resolved accurately enough and there's stored a library of different wire geometries, the right current distribution maybe is solvable. I guess it's not more complex than how faces are recognized or a 3D model is deduced from a bunch of photos. See: This is not more than an opinion. \$\endgroup\$ – user287001 Dec 15 '19 at 19:18

Can't remember the name but its the line integral of H dot dl around a closed loop = current enclosed, and since you (should) have the same magnitude current, but in opposite directions, the current enclosed is zero. That is on the conductor.

But ... I have had a problem at work with inaccuracies measuring DC current; when the DC clamp meter got too close to the coil of a 24VDC relay (designed to carry 400A), the reading on the meter would change. And then if I lined it up directly with the coil of the relay, I could get even bigger offset. It shouldn't because it has a metal shroud over the coil, but there it was. As I recall, the coil side was 1 < x < 3A.

Maybe you can poke around the area of the coil of the known working solenoid valve with your DC Clamp meter you are trying to analyze, assuming it is safe, and you have access to that point, see what happens.


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