# How does 4-quadrant metering of 3-phase electricity work?

I have a 3-phase 4-quadrant electricity meter installed because I have a photovoltaic plant on the roof of house. A 4-quadrant electricity meter means it can measure both consumption and generation of energy (forward and reverse direction).

Let's assume I have an home appliance consuming 1 kW of energy and I'm generating 1 kW of energy from a PV plant at the same time. The appliance is connected to phase A and the generator is connected to phase B.

After one hour what will be the change in readings? Will it be 0 kWh consumed & 0 kWh generated or 1 kWh consumed & 1 kWh generated and why?

My location is Slovakia, EU, the meter is Itron ACE6000.

Update
In Slovakia (as of 2013) it's better to consume the generated energy myself than to feed it back to the network, which should be (and is for me) the most important reason to build a PV plant.

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In Israel the scheme is selling the electricity produced back to the company for 4 times the price. So for that you'd need to measure 1kWh consumed and 1kWh generated, with the electric company billing you for X and paying you back 4X. The data sheet of the meter suggests this as well, but not explicitly. – Eli Iser Jan 31 '13 at 6:40
@EliIser: My main focus is learning the technical answer. Finances is secondary, see my update. – Peter Ivan Jan 31 '13 at 7:07
I meant to use it as an example of the requirement for the meter. To enable billing correctly the meter must measure 1kWh generated and consumed, instead of zeroing it out by itself. – Eli Iser Jan 31 '13 at 7:08
@EliIser: Yes, it seems to be the correct way but is it stated somewhere in the manual (how is it called)? – Peter Ivan Jan 31 '13 at 11:48
Since you have the meter installed, why not go look at it and see if it has two measurements or one (e.g. 2 sets of dials). – BMitch Feb 2 '13 at 15:15

## 2 Answers

As you already know, 4-quadrant electricity meter just means it can measure the flow of power to the customer even if it is a reverse flow.

Your concern is whether generation and demand is recorded separately, or if the meter only records the net power flow. The key is that your meter is a "multi-phase" meter. Because your generator is connected to a different phase than your load, your ACE6000 can record the flows for each phase separately and independently.

You can see that each phase is measured and recorded on page 7 of this manual for the ACE SL7000, a brother to the ACE6000.

http://jocuccok.files.wordpress.com/2011/03/itron-ace-sl7000-tb-gb-0903.pdf

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The main point is really measuring and recording each phase separately and independently. If I get no better answer, I'll accept this one. – Peter Ivan Feb 3 '13 at 19:21
You should be able to verify this on your meter. Let your PV plant run for an hour with all your loads turned off and see how much the measurement for its phase changes. Then run another hour under the same sun conditions and see what your meter measures for that phase under those conditions. Also run a normal load at night and see how the load power measurement changes and compare to a normal load hour during peak sun. – Philip Ngai Feb 3 '13 at 22:08
It's a bit more complicated. The generator is in fact 3-phase, but intelligent so much to supply only 2 or 1 phase in poor light conditions. I simplified the question because I'm interested in those situations and the real load is never symmetric. I'm sorry for misleading you. – Peter Ivan Feb 3 '13 at 23:45
It's no problem. Do you want further analysis or is this adequate for you? – Philip Ngai Feb 4 '13 at 20:16
I found a russian manual of ACE6000, by which the meter has separate registers for each phase and that's why they're measured separately. – Peter Ivan Feb 4 '13 at 20:57

The Itron ACE6000 is a programmable multifunction meter and the way it handles your specific conditions is programmed in the device. You will have to contact your utility to confirm the exact details.

In general the power (W) across the phases are summed before the four quadrant energy calculation is performed at a rate of typically once per second.

If the power (W) is forward or towards the load, the 1.8.1 active energy (Wh) register advances and either the 5.8.1 inductive reactive energy (varh) in Q1 or 8.8.1 capacitive reactive energy (varh) in Q4 registers advance.

If the power is in reverse, 2.8.1 (Wh) advances and either 6.8.1 in Q2 or 7.8.1 in Q3 advance.

These are not the only options available.

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Doesn't seem to answer the question asked about how the metering works. – The Evil Greebo Jul 22 '14 at 15:55
As I understand this answer says: "it depends" (it might be programmed either way). Thanks. – Peter Ivan Jul 23 '14 at 21:48