RadioBanter - View Single Post - connecting dc supplies in parallel for more current

October 29th 03, 08:52 AM

On Tue, 28 Oct 2003 23:45:42 GMT, (J M Noeding)
wrote:

Connecting transformers in parallel is sometimes a risky business,

Some big power distribution transformers are sometimes connecting in
parallel with some external inductance to reduce the imbalance.

Take a separate smallish transformer with a centre tapped low voltage
secondary winding. Connect the centre tap to the load and the two end
of the small transformer to the respective hot terminals on the main
transformers. The primary of the smallish transformer is not
connected, but can contain quite voltages.

A similar approach is used when hot switching between different taps
on a large power transformer. Normally the two ends of the CT coils
are connected to the same tap on the main transformer. Then one end is
moved (break before make) to the adjacent tap and after a while the
other end is also moved. In this way, the power distribution is not
interrupted when changing main transformer taps and it does not cause
momentary short circuits on the main transformer.

Paul OH3LWR