Re: [CAD_CAM_EDM_DRO] Re: 28v power transformer

On Wednesday 21 April 2004 01:25 pm, theowyn wrote:

> I would take a meter to the primary for starters. You probably will
> see two separate coils which have *equal* resistances of a few ohms.
> I would use a Variac or another low-voltage transformer to feed a
> couple volts into the secondary side and verify the you're getting the
> *correct* porportional voltages on the primary.

This is a good approach, except the fact that a variac typically provides no
isolation...

> Then try paralleling the primaries to find the proper polarity between the
> coils (a wrong polarity cancels most of the magnetic field which results in
> high currents flowing.) At this point you know enough to hook it up
> properly.

Again, this isn't quite right. If you tie two ends together, then the coils
will be either in phase or out of phase. If they're in phase with each
other, there will be little or no voltage difference between the two
unattached wires. If they're out of phase, the voltage will be _twice_ that
of either winding -- at which point tying _those_ ends together as well more
than likely _will_ let the magic smoke out...

> Good luck and don't let out the magic smoke! ;-)