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markthespark

Hi i was havin a conversation with some lads at work today about what would happen if you connected the 12v secondary side of the tranny to a 230v supply, would you get a really high voltage but low current out of the primary side, acting like a step up transformer??

i have very limited knowledge on transformers and would be interested to know?

Muchas grassy arse:)
 
The thing is if it did work how would you test it as the voltage would be around 2760 volts ( i think):(.... wheres Tony when you need him.
Regards
MacSparky:)
 
This would not work. Check the resistances of the pri and sec windings. You will find the are in the ratio of about 20 to 1, the sec about 1/20 of the primary, so connecting this to 240 would melt it.
Also 12 volt sec at 1 amp would mean the primary would only draw a current of 1/20 amp at 240 volts, so the primary dooes not need so much csa as the secondary for this transformer.
The VA rating of the transformer for 1 amp at 12 volts will be 12VA. Since the VA rating is the same for pri and sec windings, then for the primary at 240v, the current will be 12/240 which is 1/20th amp.
So for any transformer, VxA on one side will equal VxA on the other, so you can work it all out if you know one side.
 
This would not work. Check the resistances of the pri and sec windings. You will find the are in the ratio of about 20 to 1, the sec about 1/20 of the primary, so connecting this to 240 would melt it.
Also 12 volt sec at 1 amp would mean the primary would only draw a current of 1/20 amp at 240 volts, so the primary dooes not need so much csa as the secondary for this transformer.
The VA rating of the transformer for 1 amp at 12 volts will be 12VA. Since the VA rating is the same for pri and sec windings, then for the primary at 240v, the current will be 12/240 which is 1/20th amp.
So for any transformer, VxA on one side will equal VxA on the other, so you can work it all out if you know one side.


Dont quite agree with the resistances side of things. Obviously we are talking about impedence rather than resistance

And Xl = 2 Pi FL

the L is fixed for the coil, and the frequency hasnt changed. Therefore the Xl of the coil is the same, regardless of which V we apply to it. Obviously the I drawn will relate to the V applied, and the Xl of the coil will mean it will draw whatever I it needs. The coil MAY be able to handle this, it may not, depending on the VA rating of the tranny

It isnt 'automatically' going to blow!!!;)
 
this is the reply I got back from Aurora's technical department with regards to their electronic transformers: "I suspect that if you were to put 230VAC into the output terminals of a transformer then nothing would happen that you can see. It would however blow the surge protection fuses within the transformer and probably burnout the terminals meaning that the transformer would be unusable"
 
this is the reply I got back from Aurora's technical department with regards to their electronic transformers: "I suspect that if you were to put 230VAC into the output terminals of a transformer then nothing would happen that you can see. It would however blow the surge protection fuses within the transformer and probably burnout the terminals meaning that the transformer would be unusable"


Nah,,,,,,what do they know;)
 
yep sorry it just blows i did it the other week when not concentrating.

sorry to dissapoint but no big bang or anything just didnt work.
 
Once (not so long ago in a place not to far away) i watched someone blow the Fudge out of a timed SELV fan controller! he was connecting it all up, but some how he managed to put the perminant live, and neutral in the 12v side, and he went to turn the power back on the test it, and it didnt like it (well much!!) you know why i know this, because it was me!! lol
 
Never tried it on a larger transformer but I'm sure it's only blowing the output fuse because it is now an input fuse.
I've (seen it)done it to smaller tx's using batteries and flipflops( no, not those) to "defend" property (ahem)
I tutted very loudly when I saw him (before the Disgusted of Dagenham brigade, let rip)

Bit like a cross between a cattle fence and a cattle prod. Not something you grabbed twice.
 

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