# Polyphase configuration (Australia)

Many regions of Australia are supplied via two-phase polyphase connections. Unfortunately with two-phases there is a 120 degree and 180 degrees between phases variation depending on the transformer. e.g. 415Vac, 480Vac. My home is the later. This 180 degree scenario has presented a very minor issue with a monitoring system used for microinverters (Enphase) using power line communication via a phase-coupling device. Within the home there are no appliances that take advantage of the two-phases, in essence it is two discrete 240Vac single phases. Due to voltage drop and distances in regional Australia, supply utilities installed two-phase polyphase transformers.

Another possible complexity is the voltages and power factor do vary between phases, sometimes significantly. Depending on load (voltage drop) and solar production (voltage rise).

My question therefore is: Will the IoTaWatt sampling rate (ADC) handle the 180 degree sinewaves and the higher voltage between phases, if it does, will the unit be able to be configured following the three-phase polyphase and calculator configuration provided in the documentation, obviously modified slightly to suit two-phases.

So there could be something going on here that I’m not aware of, but I’ll take a slightly educated guess.

Two phases 120° apart are simply two legs of a three-phase system. For whatever reason, one phase is just not delivered. IoTaWatt handles this in the same way that it handles three-phase. You can do it with derived (1 VT) or direct (2 VT) reference. It’s fairly common in North America, particularly in Canada, to see an apartment with what appears to be a split-phase load center that is supplied by two legs of three-phase. The voltage is 120V/208V. same ratio as 240V/415V. The “polyphase transformer” would essentially be two transformers.

Two phase 180° apart is exactly like North American split-phase, where there is three-phase on the poles, but only one of the phases is fed to a center tapped transformer to service a dwelling.

This is probably because most appliances are 240V and 415V or 480V is pretty dangerous. North American industrial three-phase is 277V/480V, but the three-phase delta motors require three 120° phases. So the 480 is useless.

This is probably the reason behind it. One such user said that each of his two legs were 32A. So 240V at 32A can use a smaller wire than 240V at 64A. You do need three of then though as opposed to two larger for single phase. In any event, you can go longer distances with less wire when you split it.

Yes. At the end of the day, it’s a 50Hz sine-wave. It doesn’t matter if it’s single-phase, or three-phase to neutral, or three-phase to phase.

If it’s two 120° phases, you treat it exactly like three-phase, because that’s what it is. If it’s two 180° phases, you will treat it like North American plit-phase, because that’s what it is.