Electrical – Transformer in parallel


Can I connect transformer secondaries with different voltage in paralel?

Best Answer

Can I ...

We have no way of knowing your capabilities, so there is no way to answer this question.

Connecting multiple transformer secondaries can yield useful results in some cases. In series, the voltages add, and the current capability is that of the lowest current winding. In parallel, the voltages must be the same, and the current capability is that of all windings combined.

The above assumes that phase was properly considered. When polarity of one winding is important relative to other windinds, the schematic shows a dot by one end of each winding. All the dot ends will be in phase, and 180° out of phase with the not-dot ends.

To usefully parallel two secondaries, both these conditions must be met:

  1. The two windings have the same open circuit output voltage.

  2. The two dot ends are connected, and the two not-dot ends are connected.

When you do this right, you get the combined current capability of both windings, and the voltage of each winding.

Connecting two windings of different voltage is a bad idea. This effectively shorts part of the transformer against itself.