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Registered Member #2028
Joined: Mon Mar 16 2009, 08:13PM
Location: Norway
Posts: 319
Hi everyone.
My school just got hold of a 3phase 1:1 transformer wired in star/delta configuration, to convert the 230V mains to 400V. This would be used to supply power to some foregin equipment. It turned out to have a shorted winding, so the entire thing will be scrapped.
What i want is to convert this transformer to a 1phase isolation transformer for my workbench, avoiding the faulty winding altogether. But as it is now it's too big and too heavvy for my use, so my question is; How much of the core can i remove? Could i simply unscrew the bolts holding the cores together and remove the crossbar at the top and bottom, or would that cause the transformer to malfunction?
The transformer i am talking about looks similar to the one in this picture:
Registered Member #2028
Joined: Mon Mar 16 2009, 08:13PM
Location: Norway
Posts: 319
Dont take any of the core off
Do you mean that i cant remove any of the core, or just that i dont have to? For you see the main reason i asked is that the transformer is, as it stands now, to heavy and too big for my use. I could remove one core leg as you suggest, but the transformer would still be on the heavier side.
Could i remove two core legs and use only the third, or would that cause the core to saturate and whatnot?
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
it has to have at least a single closed loop of core material. Or it wont work for sine waves. I would not dissasemble the core in such a way that you cant get them back to gether again. you might be able to get rid of the shorted winding, but disconecct it for now leave the core to big and heavy and test it to see if thats really going to work for you, theres no need to do a whole lot of work to it, just to find out its dead.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
The coils disconnected wont do anything, but add weight. If the sliode off easily, keep them for future use. Its had to judge from your pic how big it is. Another thought, Have the school fix it a lab project- something in which the students learn something practical. One school here had the shop kids make welders that they took home for just the metal and wire cost. When they cleaned out the storage they gave me two *heavy* rolls of the iron plate the cores were made from.
Registered Member #2028
Joined: Mon Mar 16 2009, 08:13PM
Location: Norway
Posts: 319
it has to have at least a single closed loop of core material. Or it wont work for sine waves.
I see. I'll just keep searching for a more suitable transformer then. Thanks for the replies.
Edit:
The coils disconnected wont do anything, but add weight. If the sliode off easily, keep them for future use. Its had to judge from your pic how big it is. Another thought, Have the school fix it a lab project- something in which the students learn something practical. One school here had the shop kids make welders that they took home for just the metal and wire cost. When they cleaned out the storage they gave me two *heavy* rolls of the iron plate the cores were made from.
Oh i can assure you, i still wont let them throw it away that easily
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
Have a look to see if the core is welded together, if it's not then dis-assembly AND re-assembly are quite simple. You will need to remove the former with the windings that have the short-circuit. If you can remove the iron of one of the three limbs then you will have two primaries and two secondaries to adjust input:output ratio. If you can't remove the iron for one of the limbs then just use the center limb for one primary with one secondary.
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Question about isolation transformer
