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  • Author Author: tariq.ahmad
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Workbench Wednesday 24: No-Contact Current Measurements

 

 

One of the safest ways to measure current is with a clamp. Clamps do not require you to break the circuit and they safely measure wires with thousands of amps. In this video, we measure DC current in the lab, AC current of a reflow oven controller, and the DC current in a car using a Tenma 72-722672-7226 True RMS Clamp Meter.

 

Bill of Material:

 

Product NameManufacturerQuantityBuy KitBuy Kit
72-722672-7226 - Clamp Meter, Auto, True RMS, 600 A AC, 600 V AC, 600 V DC, 28 mm Jaw Opening Max.Tenma1Buy NowBuy Now
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  • Hi James,

     

    Nice episode. I would think it would be relatively easy to build a centering bushing for the clamp.

     

    I assume that centering is only crucial for the DC current measurement, is this so?

     

    How do you think they are getting a DC current measurement? Perhaps integration of multiple Hall effect devices in the clamp?

     

    How did the meter do for accuracy below 1 Amp in the DC mode?

     

    John

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  • Hi James,

     

    Nice episode. I would think it would be relatively easy to build a centering bushing for the clamp.

     

    I assume that centering is only crucial for the DC current measurement, is this so?

     

    How do you think they are getting a DC current measurement? Perhaps integration of multiple Hall effect devices in the clamp?

     

    How did the meter do for accuracy below 1 Amp in the DC mode?

     

    John

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  • in reply to jw0752

    Hi John, here are my thoughts.

      wrote:

    I assume that centering is only crucial for the DC current measurement, is this so?

    As far as I knew, it should apply to both AC and DC. But I could be wrong.

     

      wrote:

    How do you think they are getting a DC current measurement? Perhaps integration of multiple Hall effect devices in the clamp?

    It's inhereint to the hall effect sensor works. It is just measure the strength of the magnetic field in the gap of the core.

     

      wrote:

    How did the meter do for accuracy below 1 Amp in the DC mode?

    I haven't really used clamp meters for less than 1 amp. My guess would be, they aren't very effective.

     

    I have used the hall effect for my oscilloscope on stuff in the 100 mA to 1 A range. I know that below 10 mA, it the measurement gets into the noise floor of the probe.