What will be the potential consequences if I connect a fan motor on A1 terminal of Triac?

Nazmul Hasan · ‎2018-02-21

Posted on February 21, 2018 at 14:10

Hi

renard.benoit

Please let me know the potential consequences of connecting a fan motor (Max 100W) to the A1 terminal of T435-800T (BT138-V marked on schematics) Triac? On the right schematics, please find my intended operation.

Thanking you,

Nazmul

null

Benoit RENARD · ‎2018-02-21

Posted on February 21, 2018 at 14:27

Hi Nazmul,

There is no particular functionnal issue to connect the load to A1 except your circuit immunity to EFT could be highly reduced, resulting of spurious triggering in case of Line disturbances (it is better to connected A1 to a stable potential as Line).

Note that your schematic on the right is wrong as R13/R12 and Triac gate are connected in parrallel of the load (no way to work). The driving circuit must be referenced directly to A1 (and not to A1 through the load).

Let me know if you have any other question

Best Regards

Benoit

Nazmul Hasan · ‎2018-02-22

Posted on February 22, 2018 at 13:59

Hi Benoit,

Note that your schematic on the right is wrong as R13/R12 and Triac gate are connected in parallel of the load (no way to work). The driving circuit must be referenced directly to A1 (and not to A1 through the load).

Yeah, I didn't see it through my eyes. Thanks to your careful observation.

I want to control two of my room lights, those share common neutral line. Power feed to the load from switch board via a mechanical switch and other terminal of the load connect to the neutral line nearby the load. I can't see a way to connect load A2 terminal, can you? If not, how can I improve immunity if I connect load to A1 terminal? Does a Snubber or MOV help?

Vous remercier,

Nazmul

Nazmul Hasan · ‎2018-02-27

Posted on February 27, 2018 at 10:00

Hi Benoit,

+ Update: I tried to connect the load to Triac's A1 terminal. As you already suggested resistor R12/R13 and Triac gate are in parallel. So, I'd to use a Triac driver, MOC3021 in order to fire the Triac in Q-I and Q-III. It's working fine but I found a ''hissing'' noise. Probably it's from the induction of power supply circuit (attached image). Any suggestion regarding this?

Anyway, I'm waiting for your comment on ''

I want to control two of my room lights, those share common neutral line. Power feed to the load from switch board via a mechanical switch and other terminal of the load connect to the neutral line nearby the load. I can't see a way to connect load A2 terminal, can you? If not, how can I improve immunity if I connect load to A1 terminal? Does a Snubber or MOV help?

''

Merci!

-/Nazmul

Benoit RENARD · ‎2018-02-28

Posted on February 28, 2018 at 11:42

Bonjour Nazmul,

Regarding inductor noise, as you have only change the Triac controller from direct control to opto-Triac, the SMPS current change is the current provided for Triac triggering. Then my suggestion is to check if the opto-Triac LED current you apply is much higher than the gate current of the 1st circuit.

Regarding the reference of the load versus Triac, t

here is no particular functionnal issue to connect the load to A1 except that your circuit immunity to EFT will be reduce. And you're right, a snubber in parralel of the Triac could be arrange this. A 10 nF / 51 Ohm should compensate.

Let me know if you need more

Benoit

Nazmul Hasan · ‎2018-03-11

Posted on March 12, 2018 at 06:20

Bonjour Benoit,

Sorry for being late.

Regarding inductor noise, as you have only change the Triac controller from direct control to opto-Triac, the SMPS current change is the current provided for Triac triggering. Then my suggestion is to check if the opto-Triac LED current you apply is much higher than the gate current of the 1st circuit.

Yes. you are right. I changed the value of current limiting resistor at isolation side of opto-Triac driver. Now it's working fine. Please let me know whether should I use sensitive logic-level triac (10mA gate trigger current) or standard triac ( 25-35mA gate trigger current) while firing the triac using a opto-triac driver.

Merci

Nazmul

Benoit RENARD · ‎2018-03-19

Posted on March 19, 2018 at 18:15

Hi Nazmul,

Sorry for my late reply.

If you dont have to pass EMC standard (especially versus conducted noise), please use a 35 mA Triac to ensure a better dynamic behavior: better dV/dt withstanding and better turn-off capability (dI/dt)c.

Let me know if you have more questions

Best Regards

Benoit