Re: Center tapped transformer

--- In CAD_CAM_EDM_DRO@y..., "Tim Goldstein" <timg@k...> wrote:

> I have a transformer that is center tapped on the secondary. Voltage
> from the center tap to either end is 30 v. from end to end it is 60
> volts. I know that if I want 60 volts I just connect the ends to the
> bridge and tape off the center tap. How do I connect it if I want 30
> volts at the maximum amperage possible? I realize I can connect

from one

> end to the center and get the 30 volts, but it seems like I am

missing

> out on amperage by not somehow using the other half of the coil.
>
> Tim
> [Denver, CO]

Tim,
Congratulations you picked a subject that has provoked much
discussion.

a centre tapped secondary transformer has 3 sets of windings. the two
secondaries being connected as a centre tap. the wire size of each of
the windings governs the maximum safe useable current in the primary
and secondary windings. The maximum power of the transformer in watts
is total secondary voltage multiplied by amps.

Marisses suggestion of the multiple outputs using a bridge is a good
suggestion. But if you need only a single voltage output at the
absolute maximum current then separating the centre tap (if possible)
and connecting the secondary coils in parallel (in correct polarity)
so you can have 60 volts ac at nominal rated current or
you can have 30 volts ac at twice nominal rated current. the current
in each coil remains the same, at its nominal rating. the key here is
not to exceed the maximum rated current of any of the 3 coils.

some purists may argue that minute differences between each secondary
winding can cause current to flow from one secondary coil to the
other. if this possibility concerns you then just connect the ac
output of each 30 volt coil to its own bridge rectifier and then
connect the dc outputs of each bridge together.

Bob Thomas