Re: 80V Toroid & Ferrite Beads

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Carlos Guillermo"
<carlos@v...> wrote:

>
> It's starting to become very obvious to me! BTW, how could you
> determine the proper ends of a winding to hook up in parallel if
> the terminals aren't lableled?
>

It isn't that hard, as long as you have a volt/ohm meter.

Look at this winding diagram for a dual winding transformer:

http://www.coilws.com/images/Toroidal%20Power/Schematic.gif

OK. Assume you have this transformer, and the primary leads
are labeled already, but the secondary leads are not.

So you have 4 unlabeled wires. First, use your ohmeter to
determine which wires belong to each winding regardless of
polarity. In other words, when you find two wires that are
connected, label them 3 and 4. The other two wires should
be 5 and 6, and there should be no connection between 3 (or 4)
and 5 (or 6). Now you know which wires connect to each
winding, but you don't know the polarity - you might have
to swap the 3 and 4 labels (or 5 and 6, same thing).

To find the polarity, you need to apply power to the primary.
Before doing so, make sure none of the wires can accidentally
touch each other or anything else (especially you!).

With power applied, measure the voltage on the first winding
(3 to 4). Then measure the second winding (5 to 6). They
should be the same, if it is a standard dual winding
transformer. If they are not, you cannot parallel the windings.

If the 3-4 and 5-6 voltages match, power down and temporarily
connect 3 to 5. Then power up again and measure the voltage
between 4 and 6. If you measure zero volts, then the labels
are correct. You can connect 4 to 6 and use the transformer
in parallel - take the output from 3 and 6. On the other hand,
if you measure about double the single winding voltage between
4 and 6, then the labels are wrong. Disconnect 3 from 5, swap
labels 5 and 6, connect the "new" 5 back to 3, and repeat the
test - this time you should get zero volts between 4 and 6.

John Kasunich