Calculating power consumption with a amp clamp

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Mahdi

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Electrical Engineer
Hi

I have a 3 phase power supply 380/220 connected to a MCCB with various types of single phase loads connected to it and no KWH meter is installed to measure how much power is being consumed. I only have a amp clamp.

Im thinking to measure the amps on every phase on the primary side of the the MCCB separately. Then multiply by 220 to get VA for every phase also separately. After that ill add the VA amounts and assuming the power factor 0.95 ill divide on it, to get watts.

Is this the right way?

Please excuse my english its not my first language.
 
I would average the amps across the 3 phases and use 380V x A x 1.732 x PF/1000. I would not assume a .95PF unless the loads were primarily resistance heating and incandescent lighting. Anything with a motor or electronic power supply is going to be a lower PF than .95.

But that is only going to provide you with the power (kW) of that instant in time, not the energy consumption kWh) over time. That instantaneous value is all but meaningless when it comes to power consumption, which is what you asked about.
 
Mahdi said:
Hi

I have a 3 phase power supply 380/220 connected to a MCCB with various types of single phase loads connected to it and no KWH meter is installed to measure how much power is being consumed. I only have a amp clamp.

Im thinking to measure the amps on every phase on the primary side of the the MCCB separately. Then multiply by 220 to get VA for every phase also separately. After that ill add the VA amounts and assuming the power factor 0.95 ill divide on it, to get watts.

Is this the right way?

Please excuse my english its not my first language.
Click to expand...
Well, I don't think I would assume the power factor. It could be different for any of the phases and could be quite low for some of them.
And I think your English perfectly fine......:)
 
As mentioned, the .95 PF might be a little optimistic, but if your load is fairly level you could extrapolate out and get a rough idea of the KWH.
 
Jraef said:
I would average the amps across the 3 phases and use 380V x A x 1.732 x PF/1000.
Click to expand...
FWIW, PF aside, that's the same computation as the OP mentions. Because 380 * 1.732 / 3 = 220. In both cases multiplied by the sum of the amp readings.

Cheers, Wayne
 
I've been referring to this website for the past seven years and i always find answers for my questions specially when it comes to the NEC. This is my first post here.
Please continue what you are doing its very helpful.
Thank you
 
Mahdi said:
Hi

I have a 3 phase power supply 380/220 connected to a MCCB with various types of single phase loads connected to it and no KWH meter is installed to measure how much power is being consumed. I only have a amp clamp.

Im thinking to measure the amps on every phase on the primary side of the the MCCB separately. Then multiply by 220 to get VA for every phase also separately. After that ill add the VA amounts and assuming the power factor 0.95 ill divide on it, to get watts.

Is this the right way?

Please excuse my english its not my first language.
Click to expand...
Yep..
I would use .80 PF.
As you said, that’s watts only.

you could assume and multiply by time for the kWh
 
electrofelon said:
Not sure exactly what you are trying to do, but you could ask the Power company for meter data.
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Or simply read the meter. Most commercial meters show data like kW, kWh, PD, peak PF, etc
I assumed he is wanting consumption of individual feeders.
 
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