# HELP! AC wave form for pure inductance

Discussion in 'General Electronics Chat' started by ahmed kamal, Nov 2, 2014.

1. ### ahmed kamal Thread Starter New Member

Nov 2, 2014
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why the current wave form can`t take this shape ?
assuming voltage applied at first quarter from zero

i can`t find any information about it anywhere !

2. ### BR-549 Well-Known Member

Sep 22, 2013
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• ###### 800px-VI_phase.png
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3. ### crutschow Expert

Mar 14, 2008
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Below is the simulation of two identical inductors with suddenly applied sinewave voltages. The top simulation, with the starting voltage at zero, has an initial transient current offset (the C in the equation) which requires about 2 1/2 seconds to settle to the steady-state value with the given inductor value and sine-wave frequency. The reason for this transient is that initially both the voltage across the inductor and the inductor current are zero (zero phase shift between them) so it takes some time for the inductor current to settle into the normal 90 degree shift between voltage and current.

The second simulation, with the initial voltage starting at the maximum has no such transient since the voltage and current start at 90 degrees out (zero current at the peak applied voltage).

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4. ### ahmed kamal Thread Starter New Member

Nov 2, 2014
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But do you have more articles explaining it more ?

Thank u again

5. ### crutschow Expert

Mar 14, 2008
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I don't know of any.
What don't you understand?
If you want a mathematical explanation, then you likely will have to work through the differential equations for the two different initial conditions for the application of the sine-wave voltage to the inductor. (I'm allergic to calculus so I can't be of much help with that. )

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6. ### Dr.killjoy Well-Known Member

Apr 28, 2013
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Lol isn't there a treatment for that ?¿?¿

7. ### crutschow Expert

Mar 14, 2008
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I don't think so. I'm afraid it's terminal.

Nov 2, 2014
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