triac is failing everytime..

[deepakchikane]

chukey..

will be the snubber calculations for the smps will be different than u suggest above..??

or same formula can be used for the switch mode power supply..??

 

[deepakchikane]

still my triacs are failling instead 2 triacs been connected in a series..

any help plz

 

[FvM]

Unfortunately none of the questions about trigger circuit, trigger waveforms, circuit operation mode has been answered yet.

 

[chuckey]

is TR1 switched before the mains is applied to the transformer and load?
Frank

 

[deepakchikane]

1) can anyone suggest me how to drive two triacs with single moc ic..??
2)can gate trigger current affects the o/p & zero crossing circuit..??
3)for inrush current limit what prevention techniques shid i use..??
4)how to inhibit o/p of tca 785..??

lookin forward to hearing soon..

 

[KerimF]

The following may be off topic.

I recall my first design about 20 years ago to regulate mains voltage by using relatively low power triacs, as it is done here, though to drive more than one primary coil.

For a whole year, I tried adding almost all possible protection circuits and I also tried monitoring the current of the active triac so that the next triac could be fired when the previous one is totally off (to avoid shorting the transformer in the primary side).

I ended up with a rather complex board but most of all, it wasn't reliable as I expect it to be. And I had the courage to stop the project and start another one by using power triacs that replaced the mechanical relays of a conventional mains regulator (one of the eight triacs at the primary side should be on). Since I couldn't get triacs rated more than 40A. And I don't like exceeding half of the limit (here 20A), the maximum power of the regulator was
150V * 20A = 3000 W
The 150 V is the RMS lower limit of the regulated mains voltage.

This regulator is still working in my house though I had to replace the burned fuses sometimes, when a short-circuit happens or the mains is very low while many appliances are on.

 

[picgak]

Dear All,

here i am attaching the ckt diagram of my project..

please help me out for why :sad: is failing every time (without gate triggering)

plz plz plz

I think your triacs are getting triggered by stray signals during switch on because you left the gates disconnected . Try switching on after connecting gate to A1 terminal with a 1K resistor.