Electronic – Ammeter time limits – how to understand them

current measurementmultimeter

On my multimeter, near the 10 A connector it says 10 A MAX 10sec EACH 15min. I usually measure currents less than 1 A so I never cared about this.

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Is it correct to assume that if the measured current is lower than 10 A, I can take the measurement in more than 10 sec and I don't have to wait 15 minutes?

I measured only a few times a current of about 4 A and I'm sure I didn't follow those time limits and the multimeter is still working (so far).

I read the manual, there's nothing written about this.

Best Answer

The short-term specification — 10A for 10 seconds — is an indication of how much energy the meter can absorb without going outside its accuracy specifications (and without damage). You can probably assume that for lower currents, you can extend the time proportionally to the square of the reduction, since power is proportional to current squared. E.g., at 5 A, you can probably make measurements in the short term that add up to 40 seconds.

The long-term specification — each 15 minutes — is an indication of how quickly the meter can dissipate the absorbed energy and return to thermal equilibrium. This is equivalent to an average power rating. For example, if you measure 5A for 10 seconds, which is 1/4 the energy, you should be able to do this every 15/4 = 3.75 minutes.

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