# transformer response to a step input

Discussion in 'General Electronics Chat' started by AlexK, Jun 3, 2007.

1. ### AlexK Thread Starter Active Member

May 23, 2007
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0
I saw a circuit in a book, in which 6V DC was connected to it's secondary winding and the output voltage is the voltage on the primary winding.
The transformer is a step down transformer from 220Vac to 6Vac.

The book said that suddenly disconnecting the DC input would produce an impulse of about 1000 Volts at the output.

My guess is the because the current through the secondary winding goes abruptly from constang to zero (like a step function), then d(flux)/dt is proportional to a Delta function (because the derivative of a step function is a delta function).

what do you think?
thanks.

2. ### thingmaker3 Retired Moderator

May 16, 2005
5,072
6
I think you have accurately described a part of "inductive kick."

The current in the primary goes from constant current to zero current in short time. Rapid collapse of the magnetic field induces voltage across the secondary. We can use Mr Faraday's equation: E= -N(dFlux/dt) where N=number of turns.

May 23, 2007
34
0