Electronic – Connecting a 230 V power supply to a center tapped transformer


I just bought a small toroidal power transformer, which has a center tap in the primary. It is intended to be used at either 115 V or 230 V; the leads in the primary are marked 0 V, 115 V, 230 V. I only want to use it with 230 V mains.

What is the right way to connect the primary to the mains? I think I have to connect the 0 V lead to the neutral and the 230 V lead to the phase, but what about the 115 V lead? Should I connect it somewhere or just isolate it and let it float?

Best Answer

Insulate the 115 volt lead so it can't short to anything - it will output 115 volts when the transformer is energised. Definitely do not connect it to Neutral or 230 volts!