Three phase step-down transformer

Question

I am using 415 V supply. Line to phase neutral is 240 V. I have 110 V appliances that I want to use. I have created 11 different points for which I want to use this appliances, and want to install a three phase panel for it.

What three phase step-down transformer should I use that will give me phase to neutral voltage of 110 V?

Answer 1

You don't need to use a three-phase transformer if you only need a single-phase 110 V supply. If you're going to put in eleven 110 V points you may want to use three-phase just so that the loads on each phase are reasonably balanced.

^{simulate this circuit – Schematic created using CircuitLab}

Figure 1. Star (wye) connection and delta connection. (Voltages are standard European voltages.

You can use transformers with 240 V or 415 V primaries depending on whether you are connecting in star (wye) or delta. Figure 1 shows only one phase. You need to figure out whether the 110 V secondaries are to be isolating or have one conductor neutralised or centre-tapped for 55-0-55 configuration depending on your application and local regulations.

Answer 2

You should use 415/190, since line to line of 110 V is 190 V.