# How to measure electric power?

Discussion in 'Electronics Resources' started by ArFa, Oct 1, 2013.

1. ### ArFa Thread Starter New Member

Apr 24, 2011
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0
Hi all,
I want to measure output voltage, output current and output power of a 3-phase power generator, and send those data to MCU, how can I do that ?

2. ### Alec_t AAC Fanatic!

Sep 17, 2013
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What nominal voltage/frequency?

3. ### ArFa Thread Starter New Member

Apr 24, 2011
9
0
I think it's 320 V / 60Hz

4. ### #12 Expert

Nov 30, 2010
16,671
7,314
3 current transformers, 3 voltage transformers, 6 rectifiers, 6 resistors, and 6 capacitors. These will give you a DC voltage proportional to each current and each voltage.

5. ### t_n_k AAC Fanatic!

Mar 6, 2009
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That setup won't give you the means of finding the real power - only the apparent power.

6. ### #12 Expert

Nov 30, 2010
16,671
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OK. So go ahead and finish up what the OP needs.

7. ### crutschow Expert

Mar 14, 2008
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3,370
If you need real power then Analog Devices and others have chips that generate an indication of real power from the isolated current and voltage sensors that you would need to add in each phase.

8. ### WBahn Moderator

Mar 31, 2012
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Does the generator have a fourth neutral wire that potentially carries current? If not, then you only need to sense phase current in two wires and the voltage between those two wires and the third. That will let you compute real power very easily and you can get apparent power and power factor without much trouble, either.

If you are willing to assume that the generator is adequately maintaining the phase voltages and phase relationships, then you can get by with a single voltage measurement to establish your phase reference and just infer the other one.

If you have a current-carrying neutral, then you need to measure the currents in all three phase lines and the voltages between each of them and the neutral.