Hall Effect Sensor to Measure Low Frequency Current

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Besoeker said:
If the scope is displaying the output from the Hall effect device as a sinewave, can't you just take the peak and divide by sqrt(2) to get RMS?
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Given that these are pulses driven by a VFD, I rather doubt that the Hall effect device outputs will be sine waves. At least not without some serious low pass filtering.
 
GoldDigger said:
Given that these are pulses driven by a VFD, I rather doubt that the Hall effect device outputs will be sine waves. At least not without some serious low pass filtering.
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It's motor current that's being measured. The motor inductance usually results in the current being a fairly good sinewave.
 
Besoeker said:
It's motor current that's being measured. The motor inductance usually results in the current being a fairly good sinewave.
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Besoeker, you are obviously right. The voltage is PWM but current is fairly smooth sine-wave.

And about your other question: No, I can't just look at sine-wave peaks and divide them by 1.41. The test is being witnessed by a third party certifying body and they require measurement readings from a calibrated device.
 
LMAO said:
Besoeker, you are obviously right. The voltage is PWM but current is fairly smooth sine-wave.

And about your other question: No, I can't just look at sine-wave peaks and divide them by 1.41. The test is being witnessed by a third party certifying body and they require measurement readings from a calibrated device.
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I use a Tektronix TDS220 which calibrated anually. Besides showing the waveform, it has a measurement facility. Would something like that do?
 
Besoeker said:
I use a Tektronix TDS220 which calibrated anually. Besides showing the waveform, it has a measurement facility. Would something like that do?
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Tektronix THS. It has RMS measurement function but the reading fluctuates a bit but the surveyor seems to be happy. So it's all good.
 
LMAO said:
Tektronix THS. It has RMS measurement function but the reading fluctuates a bit but the surveyor seems to be happy. So it's all good.
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A result! Well done that man.

FWIW my TDS is a predecessor of this but looks the same.

 
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