[SOLVED] Triac and Optotriac circuit

[Scolioza]

Hi all, folks !

I have no experience in designing power electronics. I have a small automation project. The requirements are to switch on and off some vents. according with temperature. The client wants to be able to use manual and auto mode.

The uc. part was easy but since I dont have experience with power electronics I thought that it would be a good idea to ask another opinion, so I came to you.
I have the following concerns:
1. It's ok the way I fire the main triac?
2. The snubber is ok? (all vents consumption is 250 W)
3. For the optotriac is ok the trigger circuit?
4. Is there a problem with the switches?
5. The driver that the vents are using now is also made with triacs, because the client wants to be able to change speeds of vents manually. The triac that I want to use will act as a relay. But since I use zero crossing optotriac I am thinking that it will be a problem, because inside the current driver it might be another zero crossing triac and it's triacs will not fire.
Thank you in advance.
PS Please excuse my english

 

[red_alert]

The schematic looks ok (it's the datasheet suggested application circuit); you may find aditional information here: https://www.fairchildsemi.com/application-notes/AN/AN-3004.pdf.

Anyway, there could be a problem with series zero cross detectors indeed. Though as long as your main triac is in OFF state, the vent (and its associate triac driver) will see a zero voltage across it and once your main triac is firing, the vent's triac driver will se a rising voltage (from initial zero value) so it might consider it as a zero crossing point.

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Btw, you better put a current limiting resistor in series with your LED as the initial current (when series capacitor is discharged) might be overkill.

 

[Scolioza]

Thank you for your help. I made some tests anf it works.