reverse transformer connections

[Jeremiah]

Is it okay to connect a (prim:415v sec:24V) transformer the other way around such that 415V can be obtained from 24V applied to the secondary instead?

 

[flatulent]

yes

Yes. Transformers are totally bilateral. The catalog descriptions list the most popular use to increase sales.

 

[Jeremiah]

contd

Thanks for your reply.

I am trying to test some equipment that has a transformer with a 415V primary and mutiple secondary o/ps - 240V, 40V, 17.5V, 10V.

I only have a 240V supply so I initially thought of reversing the connections on a temporary 415V/24V transformer and then feeding the 415V o/p to the 415V i/p on the transformer of the equipment under test.

Is it in fact possible to feed 240V to the 240V SECONDARY i/p described and obtain the remaining secondary outputs (40V/17.5V/10V)?

 

[flatulent]

yes

The autotransformer function will work. The only limitation is that the current in or out of each winding will have to be within the rating for that winding.

For example, if one winding was originally rated for 5W power (VxI) you can only put 5W into that winding. You will then be limited from drawing more than 5W from the 240V winding even though it was rated for 100W.

There is a further safety issue. The ground/earth wire from the wall socket has to be connected to the similar point on the equipment you are powering. This may require your running a separate wire. Also these HV terminals on the connection between transformers need to be shielded from accidental contact with human bodies and other conductors.