Transformer on DC


Why Transformers Can’t step Up Or Step Down A DC Voltage or Current?

It is because transformer works on the principle of electromagnetic induction i.e. it will work only with currents that produce varying magnetic field that will cut the conductors and induce EMF.
The flux produced in the transformer will not change in its magnitude but rather remain the same and as a result EMF will not be induced in the secondary coil except at the moment of switching on, So the transformer may start to smock and burn because;

In case of DC supply, Frequency is zero. When you apply voltage across a pure inductive circuit, then according to

                              XL= 2 π f L

If we put frequency = 0,
then the overall XL (inductive reactance) would be zero as well.
Now come to the current, I = V / R (and in case of inductive circuit, I = V / Xl )   …. 
Basic Ohm’s Law

In the transformer 
I =E/Z
Z= R+iX
R is low hence 
Current will be very high


If we put Inductive reactance as 0, then the current would be high (Short circuited)…


So, If we apply DC voltage to a pure inductive circuit, The circuit may start to smoke and burn.



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