Multiple passes through DC Clamp-on meter?

Status
Not open for further replies.
R

richwaskowitz

Senior Member
Location
Shelby Twp. MI, near Detroit
Can anyone confirm (due to past experience) that one may pass a (DC) conductor through the jaws of a Hall Effect type clamp-on DC ammeter multiple times to multiply the resolution just we like we have been doing for years with AC circuits using CT type AC clamp-ons? I just tried it with a Klein meter (becasue IT has a MAX capture feature and the other meter I have with a 200 mA scale does NOT have MAX capture) and the results I was getting were not proportional. The lowest scale on the Klein is 5 A with 0.1 A resolution. I need ten times that so I passed the measured conductor with 100 mA on it through ten times. Did not come up with 1 A.
 
In theory, multiple passes will simply multiply the current.

In practice, you can see problems caused by things like not having the conductor centered in the window. In theory it doesn't matter where in the clamp the conductor is, in reality it does.

For what it's worth, most of my experience is with 'active closed loop' hall effect sensors, not clamp on multimeters. With these sensors we regularly use multiple turns to multiply the value being measured.

-Jon
 
In general there is no "good" way to measure DC current with a clamp meter especially with low current (exception: maybe there are expensive-er meters that work well, I haven't seen any meters under $500 work well).

The best way is break the circuit and use in-line DMM. Another way is put a resistor in the circuit and measure voltage across it.
 
Thanks for the alternative suggestions, but I am aware of all of those things. If I had the right in-line DC ammeter with the scale I need, I know I could get a fairly accurate reading (based on the specs of the meter). This is more of a question as to the basic operation of Hall effect sensor-based ammeters. The meter has a published accuracy but it does not include tricking the thing with multiple turns. I just want to understand, for my own edification, if passing 1.00 A DC through a conductor and passing that conductor through the jaws of the ammeter will result in a reading of 10.00 A, or will it be something less?
 
richwaskowitz said:
Thanks for the alternative suggestions, but I am aware of all of those things. If I had the right in-line DC ammeter with the scale I need, I know I could get a fairly accurate reading (based on the specs of the meter). This is more of a question as to the basic operation of Hall effect sensor-based ammeters. The meter has a published accuracy but it does not include tricking the thing with multiple turns. I just want to understand, for my own edification, if passing 1.00 A DC through a conductor and passing that conductor through the jaws of the ammeter will result in a reading of 10.00 A, or will it be something less?
Click to expand...

As long as the jaws still close properly and the wires are reasonably centered inside the clamp (not very sensitive at all and you can confirm by running constant current through a single turn and moving the wire and clamp around), I am not aware of anything that might account for a reading that differs from the exact product of the amperage and turn count.

The usual caution applies to make sure that all of the turns are in fact running in the same direction.
Ten turns with one turn going backwards through the clamp should read exactly the same as eight turns all going the same way.
 
Status
Not open for further replies.
Top