Factory transformer help please

[mainebankelec]

We were working in a bottling plant today and chief engineer comes over to say we have a problem on one the machines. Turns out the transformer has been connected wrong by passing 110v -0v connected together.

We went got a replacement transformer but now are stuck on reconnecting it

No matter what way we connect it still seems as if it burnig out?

connection are as follows

we have incoming 3p and earth connections and require 110v out

on one side of transformer connection are 0v 230v 400v and sch

secondary side has 110v and 0v

also a earth spade connection to the frame

my query is how to we reconnect this the original transformer has 415 415 0v 12v 110v connections.

As you can tell we have not had much experience with transformers

 

[Knobhead]

You’ve bought the wrong transformer for a start. If you need 12V you’ll have to buy another. Either the correct tappings 110 – 12 – 0V or an additional 415 or 110 - 12. You will struggle to get the correct one off the shelf so an additional transformer is your best bet. You won’t have 3ph to the primary just 2ph.

Has this machine ever run? If as you say 110 & 0V were connected together it couldn’t have.

You’ve 3 options

View attachment 7110

 

[mainebankelec]

12v not used on original transformer. Machine did work but some connect a switch up with sec side of old transformer straight across it and old transformer burnt out

 

[Knobhead]

Get rid of that switch for a start then. Out of interest, you did get the same VA rated transformer didn’t you?
An old problem is a local 110V supply is needed so a quick fix is tap in to the nearest control transformer. That could be your switch.

 

[mainebankelec]

We got a 100va transformer as all this does is provide a contactor coil 110v to run so that voltage is not high outside at a limit switch. My query is switch used to be there they were just refitting it to be able to isolate the hopper. On a transformer is the 0v a neutral or can it be earth as line voltage is 230v between L- e so earth to 0v and 230v L into terminal marked 230

 

[Knobhead]

0V is a neutral if it’s connected to earth giving you 110V - N. This is good practice. Have a look at the drawings I sent.

Where has the 230V come from?

 

[Knobhead]

How did you go on with this?