Why did the fuse blow when a DC supply was connected to a transformer?

AI Thread Summary
Connecting a DC supply to a transformer causes the fuse to blow because transformers are designed to operate with AC voltage. When DC is applied, the transformer behaves like a short circuit due to its low resistance, leading to excessive current flow. The iron core of the transformer creates a magnetic field that initially resists the current increase, but this back electromotive force (emf) is insufficient to prevent the fuse from blowing. The rapid rise in current ultimately exceeds the fuse's rating, resulting in failure. Understanding these principles is crucial for safe experimentation with transformers in a lab setting.
dhivakhar
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my friend gave a dc supply to a transformer in my college lab accidentally and the fuse went off can i get an explanation on why this happened?
 
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Transformer work only with AC voltage. For DC transformer act just like a short wire (a very small resistance ).
 
Jony130 said:
Transformer work only with AC voltage. For DC transformer act just like a short wire (a very small resistance ).
Can you please explain how a transformer shows very small resistance to a DC supply?
 
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Actually this sounds like a disguised homework question. If you are messing with transformers in lab you should already know the answer to the question.
 
Because transformers is essentially just two or more coils of wire wrapped around the core. And wires has "low" resistance.
 
dhivakhar said:
my friend gave a dc supply to a transformer in my college lab accidentally and the fuse went off can i get an explanation on why this happened?
You have a careful smart friend
 
Actually, if your friend had been able to measure the way the current varied around the time of switch on, he would have found that the current value followed a curve, because the Iron core of the transformer behaves like an electromagnet. The magnetic field energy takes time to build up and it produces a 'back emf' which delays the DC current increase (This would be fairly quick with a mains transformer - only a few tens of milliseconds before the fuse started to blow.)
 
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