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Measuring 3 phase power current

  1. Aug 18, 2011 #1
    Hi there all
    I'm looking to measure current in 3 phase cables, and would like some advice on any current clamp models you'd like to recommend. However, I'm not entirely certain on the method as well; I've used current clamps before on single phase cables, and I'm aware that you need to clamp only around the live, as the fields of the currents flowing in the live & neutral cancel each other out. Is the same true for all instruments? For three phase do you have to clamp around each live individually, or is there a method just to clamp around the 5-core cable?
    I only ask in hope as in the situations where I need to measure these currents it's tricky if not impossible to clamp individually to each live core
    Thanks for reading
  2. jcsd
  3. Aug 20, 2011 #2
    I'd be interested in understanding 3 phase power better as well. I'm guessing that if you have 5 conductors you have 3 live wires each 2/3Pi out of phase with each-other, a return, and a ground If I had to go at it with my current knowledge, and the 1 multimeter I own, I'd measure the RMS current flowing in each of the lines which would tell me the actual current flowing. That's the current actually being consumed resistively plus the ebb and flow from capacitive and inductive components. I could also measure the current flowing on the return line which would tell me the net RMS current from all the lines. Then it would be a matter of figuring out power factor. Can anyone think of a better way; mine is pretty ghetto?
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