On Feb 10, 9:40*am, nesesu wrote:
On Feb 10, 8:17*am, JW wrote:





Hi all,

Is there any reason that a 120VAC to 120VAC *isolation transformer would
draw 2.54A on its primary when there is no load present on it's secondary?

Part reference:http://www.temcoindustrialpower.com/...rs/FT2036.html

datasheet:http://attachments.temcoindustrialpo...o/Federal_FB_1...

I finally got around to wiring this transformer, and I noticed something
that doesn't seem quite right to me. I have it wired for 120VAC (H1
connected to H3 and H2 connected to H4) and it seems to be working as I
get about 120VAC on the secondary, ( wired X1 to X3 and X2 to X4) but with
no load on the secondary, the transformer is drawing 2.54 Amps.

Looking for a sanity check I guess. I'm beginning to think the thing may
be defective... Email to the Temco has produced no response as of yet.

As a quick test, disconnect all the windings from each other and then
power up any ONE winding and see what the current draw is.
I see that it is a 15kVA rated, so it is not unreasonable that the
magnetizing curent is that high, but the actual power dissipation
would be much less than that current suggests. It is probably working
correctly, but a bit of an overkill for the average workbench.

Neil S.

Sounds VERY reasonable for a 15kVA transformer. 2.5 A suggests
coupling ratio on the order of 0.982, not bad for an AC mains
transformer that weighs that much.

If it bothers you, you can add a high quality AC cap in parallel
around 55 uF. That should 'resonate' out the reactive current assuming
120Vac, 60Hz yields around 127 mH.

Or, ignore it and let your house wiring dissipate a bit of power less
than 1W ?