Transformer problems

[riotmaster]

Is there any way that you can parralel up two 240-110V 3.3kVA transformers in order to achieve a greater kVA without blowing the 13A plugtop fuses.

And if not, why is it that this happens, when you make a link between the two sockets basically? (We tested with no load, the fuse blew instantaneously)

Any ideas?

 

[Notsosmart]

You are not observing correct polarity correlation. Although they are centre tapped with 55v either side they still have polarity.

BTW you will not get double the KVA

 

[riotmaster]

Ok thanks for the reply, I knew I wouldnt achieve double, but I just wanted at least 4.5ish.

What would I have to do to achieve that then, just try reversing one of the transformers' polarity in the socket, simply swapping the two 55V live tails?

 

[Notsosmart]

When you open the lid of the Tx are the O/p's labelled; Or are the Tx's the type with the gravel looking material inside?

I say yes you probably need to change the 55v connections (within one transformer) with a cautionary caviat, that as as you have already tried & blown fuses then I suppose you will be careful not to set fire to them or the building or hurt yourself.

You may not achieve 4.5KVA continuously as it is only recomended that two transformers in parallel only draw 110% current rating.

Could you not buy/hire a larger TX?

 

[riotmaster]

I wish... but unfortunately the wholesaler in afghanistan is shut this month...

The outputs are brown/blue in one, red/blue in the other, with both blue connections have a link to earth(?) But I cant see the connections, the transformer boxes are filled with what we refer to as gunf!

We tried changing the polarity by splitting the link and crossing the lives, again the blowing of fuses took centre stage.

Surely if one of the 55V is linked straight to earth, then even without them linked it would just blow the fuse? Only when our link is connected does the fuses blow...

 

[Notsosmart]

I wish... but unfortunately the wholesaler in afghanistan is shut this month...

The outputs are brown/blue in one, red/blue in the other, with both blue connections have a link to earth(?) But I cant see the connections, the transformer boxes are filled with what we refer to as gunf!

We tried changing the polarity by splitting the link and crossing the lives, again the blowing of fuses took centre stage.

Surely if one of the 55V is linked straight to earth, then even without them linked it would just blow the fuse? Only when our link is connected does the fuses blow...

One side of both of the 55v are linked to the centre tap (+55v & -55v giving you the 110V)

So I would say that you need to make sure that you are connecting like to like & not one leg to the centre tap. Silly question but have you metered the lives to check you havn't got a faulty transformer; maybe meter between two transformers outputs & see what you get. (If you get 0V then that is your cross connection, something else (110v); then they are opposite poles (55v); then one is a centre tap.