# 3 Phase Installation - Factory

Thought of using Iotawatt in a manufacturing factory to monitor 3-phase electricity consumption.

The requirement is to monitor 440V. Since I’m a noob to electricity, I’m worried about the 3-phase VTs(No derived reference). I believe I need to procure 440 VTs separately.

Will I need three different power points from each phase in the circuit breaker to plug VTs? Or are there any workarounds for it?

Thanks.

This may be of interest to you:

I’ve not seen a 440V service. Where is it and is that the phase to neutral or phase to phase voltage? What do you want to measure, and is there a neutral conductor on the service? In the above installation, the mains are measured with three (pairs) of CTs and three transformers on the 277V phase to neutral circuits. However, there are some delta connected machines and transformers that are 480V. They are easily monitored using either three or two CTs. IoTaWatt can do derived for the phase-to-phase (480V).

So the more I know, and possibly a picture or line diagram, the better I can advise.

Yeah that post was so helpful.

240V is the phase voltage. 440V is the line voltage. Want to measure watts.

The place where I stuck is the plugging of VTs to the each phase(direct reference).

Should I need an electrician to create three new power sockets from each phase wires(RYB) for VTs?

Those voltages (240/440) cannot be right. If the phase to neutral is 240V, the phase to phase would be 416V. If the phase to phase is 440V, the phase to neutral would be 254V. What country is this?

Regarding your question about three sockets, you will need either three sockets or hardwired three transformers to do direct reference. You can also use a single VT with derived reference.

Yeah I was wrong. It’s 230V phase voltage.

Will the derived reference work fine (plus or minus 2-3%) with all types of 3 phase connection?

I somewhere heard sometimes in industrial 3-phase you can expect a voltage difference or fluctuations between the phases. If that’s true, how Iotawatt can manage it?

Btw, Happy New Year Bob and The Community

Yes it can be used with all types of three-phase. 2%-3% is usually possible.

Yes, voltages can vary between phases, and derived reference assumes the same voltage on all phases. That said, one of the phases will always have the correct voltage, and if the other two vary it will introduce some error. Doing the math, 5% variation in the other two, in the same direction, would introduce a little over 3% overall error. I would consider consistent 5% voltage variation to be very unusual.

All that said, you can add additional VTs for one or both of the other phases if it’s a problem.