Re: Combining dual secondaries of a toroidal transformer

On Sun, 18 Feb 2007 05:00:19 GMT, "Homer J Simpson"
<nobody@xxxxxxxxxxx> wrote:


<furtherside@xxxxxxxxx> wrote in message
news:1171770731.461084.227630@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Hi, I have a fairly good sized toroidal transformer that has two pairs
of primaries and two pairs of secondaries. The inputs are both 115V
and the outputs are both 33V, at 7A. I'd like to combine the outputs
in parallel, to give me 33V at 14A.

Connect the two secondary commons together. Now check across the other two
leads with an ammeter for difference current. If it's only a few mA you are
probably OK.

---
Absolutely, positively, definitely NOT.

You're a licensed electrician, where???

In the first place, the secondaries don't have "commons", they only
have starts and ends. Two leads from the secondaries should be
twisted together and one of the primaries energized (with the leads
of the other kept separate and, preferably, taped up to avoid danger
of shock or short) then the voltage across the unconnected
secondaries should be measured with a _voltmeter_. If the reading
on the voltmeter is 66 volts, then the start of one secondary
winding is connected to the end of the other and they're wired in
series. In order to connect them in parallel they should be
disconnected and each connected to the other secondary lead.

Once that's done, the primary leads should be twisted together in
pairs and those pairs connected to the mains while monitoring the
secondary voltage. If the voltage is zero the primaries are wired
out of phase and should be connected in reverse. That should cause
the secondary voltage to rise to 16V.


--
JF
.

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