Transformer

[hareng]

Transformer fully disconnected wiring.

240V input to 110V Orange output = 5.08 Ohm
240V input to 0V Grey output = 3.28 Ohm

0V input to 0V output Grey = 0.4 Ohm
0V input to 110V output Orange = 1.97 Ohm

Output side 0V to 110V = 2 Ohm
Input 0V to 240V = 5 Ohm

 

[shenion]

So, the transformer is shorted primary to secondary. Looks like the two 0V terminals are connected together.

If it is an autotransformer, then that is how it would be. Unless the rest of the output side is completely isolated from the case or ground, it will trip the RCD.

Given the resistances, you would expect 240V in to 0 to be twice that of 240V to 110V if it was an autotransformer. It does not look that way.

I can't find the part in a search, you might have to guess on a replacement: 240V in 120V out. It would need have an output current similar to the value of the fuse on the output side.

 

[hareng]

Latest, just wired power feed in through the fuse and seems to work.
However long it will last know idea.

Everyone many thanks for your help, hope to repay the compliment its probably saved me two days downtime plus parts.

 

[Wedg1e]

^^

In general terms it does if you have fuses, single pole switches, embedded thermal cutouts and suchlike. They should be in the live side for safety.

Well yes, obviously, but a transformer will 'transform' irrespective of which way the L and N are connected.

 

[rtbcomp]

....... a transformer will 'transform' irrespective of which way the L and N are connected.

Well, yes, obviously

 

[voipio]

Well yes, obviously, but a transformer will 'transform' irrespective of which way the L and N are connected.

But if it's an autotransformer sharing a common "0V" connection, and that 0V is connected to live, it will indeed transform but the output will be referenced to live, so the "0V" output will be at 230V whilst the "live" 110V output will be at approximately 120V relative to the input neutral. Hardly ideal, and probably the reason why the circuit kept tripping the mains.

The buzzing off load was probably down to the transformer laminations or windings vibrating. Many "buzz box" arc welders do this when they're off load.