Repair or replace the large transformer in a SW3048E

[clivejo]

I need to repair or replace the larger transformer in a Trace branded SW3048E inverter.  The coils seem to be shorting on the 48V side.

[joestue]

use a D cell battery, an amp meter and a volt meter to check the resistance.... it is supposed to be ~~tens of milliohms? (i don't have one to tell you for certain)

but the 13.8v rms winding of a 1kw transformer i have measured something like 4 milliohms.. so scaling that up to something twice the size, but 4 times the voltage.. its possible the dc resistance is only 10 milliohms.

if you have a shorted turn, plug it in from the 120vac side in series with a 500 watt halogen lightbulb to find out for sure.

[clivejo]

The output is 230VAC 50Hz.  I'm in the process of trying to get it out of the inverter.  They didn't make these units easy for repairs!

[mab]

Well if you know it's the transformer you can either rewind it yourself, or (if you have the money) use a firm like this:

http://www.jmstransformers.co.uk/pages/rewinds.php

who will replace the old windings like for like.

[oztules]

The rewind should be straight forward..... probably only 30 - 40 turns of multi in hand wire to get the copper cross section up.

I did a rewind for 48v 6kw inverter here:  http://www.anotherpower.com/board/index.php/topic,780.0.html

Maybe you can get some ideas from that conversion.


,,,,,,,,,,,,,,,,,oztules

[clivejo]

I need to get it out of the chassis first to get a good look at it.  The small and medium transformers are easily removed and just drop down. The large one however will require the entire inverter be stripped out, rivets bored out etc 

Its hard to get a good clear photograph but can you see where I have circled, there appears to be a break or some kind of damage?

[joestue]

i don't know what i'm looking at for certain but i'd say there is nothing wrong with that transformer.

[Mary B]

Looks like one winding is pushed down. Long as it isn't broken I don't see that as the issue