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Problem in firing the TRIAC

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Engr.Irfan

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Hey guys im working on a BTA41-800 triac . i just want to turn on my triac when 2nd zero-cross imean my load is a power transformer so i dont want my transformer turn on at peak value of AC 220V input. i just want my transformer turn on through Triac at zero-level crossing to reduce the inrush current.
Okey my problem is that im detecting the zero-crossing using op-amp and X-OR gate.
Case 1 : In start up my circuit will work fine when input (12VPP AC ) to op-amp starts from negative cycle to positive .

Case 2 : In start up if the (12VPP AC ) waveform starts from positive imean from peak at that time my circuit will not work fine. i will generate an extra high (+5v) signal at the output of x-OR gate which is what idont need.

my requirement is that i want to make a logic which can skip the first output pulse of X-OR and take the second pulse (2nd zero-crossing) as a final output.

Attacment likns given below

https://obrazki.elektroda.pl/3586395000_1512497886.jpg
https://obrazki.elektroda.pl/6252767500_1512498170.jpg
https://obrazki.elektroda.pl/4358625000_1512498366.jpg

Regards: Engr. Irfan
 

Please read this:

wikipedia - inrush current

Worst case inrush happens when the primary winding is connected at an instant around the zero-crossing of the primary voltage, (which for a pure inductance would be the current maximum in the AC cycle)

That's it, you should connect (and disconnect) your power transformer at peak voltage (positive or negative, it doesn't matter).
 

Hi,

You think you reduce inrush current when you switch ON at zero cross....Indeed the opposite is true for transformers.
To avoid reduce inrush current of transformers one should switch ON at 90°.

Klaus
 

my requirement is that i want to make a logic which can skip the first output pulse of X-OR and take the second pulse (2nd zero-crossing) as a final output.

See, this zero crossing pulse appears at every 10 millisecond. So, when you attend this zero crossing pulse within ISR or polling, some amount delay should be there before attending the next zero crossing pulse so that firing of TRIAC at wrong position could be avoided. Have you made any logic? Try to make it yourself and post in this forum.
 

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