What happens if dc supply is given to a transformer?

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boda devsingh

  • Mar 14th, 2013

If DC supply is given to the primary of Transformer then DC current flows through primary winding which is constant(time invarient).For production of emf in any winding the current flowing through that must be sinusoidal since e=L*(dI/dt).So in the given case ie, for DC input,no emf produced in primary winding. So net voltage in the primary winding will be (Vin-0) more due to which primary winding draws more current which leads to burning of winding.

In the case of AC voltage input emf produced in the primary,lets say e1 then net voltage in the primary is (Vin-e1) less, so the primary winding draws less current and the winding will be safe.

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Prachurjya Parashar

  • Mar 19th, 2013

When dc current is supplied to the X-mer, the primary side will draw a steady current due to which a constant flux is generated. Hence no back emf is produced. Thus the primary side of the X-mer which is a low resistance side draws excessive current ultimately resulting in burning out of the terminals.

Thus, to limit the effect of application of dc to X-mer a high resistance is connected in series to the primary side of the X-mer.

transformer works on the principle of mutual induction which means rate of change of current or charges induces e.m.f..
hence alternating current is the one in which current varies with respect to time and when direct current is sent to transformer there will be no change in current and no mutual induction and hence transformer doesn't work..

aniruddha mani

  • May 18th, 2013

The secondary winding of the tmer will burn as there is no back emf in the primary winding of the tmer.

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  • Jun 25th, 2013

dc has no alternating waves so there is no induced emf in the secondary. so dc is applied to primary there is no impedance in the primary due to dc.hence only resistance which is very less in the tfrmr windings.due to that primary will burn out.

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I understanding what the question generally is asking, the question needs to be more specific to how the DC is being used when hooked up to a transformer. An example is a Balun which is a transformer or a coupled inductor (seen in switching power supplies, impedance matching networks ect) is used to pass DC or any current of different potentials. There is no specified voltage or current in the question so A direct current initially will "charge" or create a stored porential in the transformer and if the DC is removed it then creates a electrical current in the secondary of the transformer or "Material" in a coupled inductor. In magnetism the stored potential or Remanence is the amount of flux density which remains in the material after the external field is removed. Also when the transformer charges its resistance (or reactance) increases so it could be thought of as A open switch.

I would guess the burn up happens because no one converted the transformers designed volt-amp rating and frequency to what would be the "DC rating"; if done properly DC will make the transformer conduct then stop conducting when charged just like a capacitor. Capacitors are an analog of an inductor so too much voltage they too burn up.

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  • Jan 29th, 2014

When DC current passed through the transformer.....the primary winding was burning.....

so only AC current use in the transformer......

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shobhit nagar

  • Feb 3rd, 2014

if we supply dc to the transformer then there will be no emf induced in the coil the emf generates only in case of ac and dc may also burn to the transformer.......

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  • Mar 2nd, 2014

transformer has high inductance and low resistance. in dc supply there is no inductance only resistance will act in the circuit so high current will flows through the primary of the transformer. for this reason coil and insulation will burn out.

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  • Mar 14th, 2014

When DC supply applied to transformer the rate of change of flux is zero so output voltage iz zero.Thats why transformer is not work on dc supply.

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  • Mar 27th, 2015

the t/f will be short ckt .because the t/f work on mutual induction when dc supply given it acts as self induction means the primary flux will not mutual to the secondary when given dc supply at primary flux increase during some time the t/f may get damage.the alternate cycle while required in ac only not in dc.depend on the form factor the step ration will be depend .these are the main condition we are giving ac supply to the t/f

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  • Mar 29th, 2015

when dc supply is applied on xmer its primary winding is burned ......
2--- cause. waveform of dc is straight line and ac waveform is alternating.. dc is not good xmer....

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