Is there any way to filter out TRIAC humming

[localcrack]

You missed the snubber for the opto...
did you google the data sheets?

sorry it still don't even come under the term project.

damn I just lifted this of a data sheet...

it is a snubber for firing a triac, it's not necessary because I am using BTA12-600BW snubberless triac.

Posted on: September 11, 2014, 07:17:48 19:17 - Automerged

Did you open the book I posted. It has a sections about noise reduction(16 and 17). Also please inform the rest of us how of the humming appear. A picture of your full setup would also be nice

I read that section and I added RC snubber in my design

[pickit2]

it is a snubber for firing a triac, it's not necessary because I am using BTA12-600BW snubberless triac.

Posted on: September 11, 2014, 07:17:48 19:17 - Automerged

I read that section and I added RC snubber in my design

So what function is R1, C3 doing in your design? is it Belt&braces?
so the problem I can see is you can't follow data sheets, or take in what people tell you. see Attachment marked in red
I see you are using a MOC3021 and I have shown you part of a data sheet that has snubber components for that device.

you then add (again not revealing your BOM) your using a snubberless triac, then you respond to Sideshow Bob with "I added snubber in my design".

My thoughts on this topic have not changed, your saying its your design, yet you post a concept diagram that is in all data sheets for triac firing.
you have not added to design, taken from a data sheet, but you taken away components from those shown on the data sheets, I have read.

 

[Sideshow Bob]

Not meant to be nippy. But have you done a serch like this https://www.google.no/search?q=triac+motor+control+noise+reduction
Quite often noise reduction is not doing just a single approach. But the sum of several approaches or attack angles

[Ichan]

But till some times some Fan generates noise.

Would you share what fan generate noise and what fan is not?

-ichan

[PeterMcMonty]

About triac driving and snubber networks, for several years I used triacs to fire asyncronous motors (about 1/2 to 1 HP) with phase shift capacitor for gate opener controllers. I always used BTA12-600 triacs, that are very robust, and MOC3061 (or MOC3062) zero crossing optotriacs to drive triacs.
When I needed torque control I substituted zero crossing optotriacs with non-zero crossing devices such as MOC3052.
Then I have some hints about triac driving:

1) for 230 Vac I suggest to use MOC3051, MOC3052 or MOC3053 instead of MOC3021, because MOC305x are rated to 600 V while MOC302x are rated to 400 V only, and when I work on AC mains I prefer something that gives me more confidence, expecially when you consider the voltage across motor phasing capacitor.

2) I found a snubber network that is derived from that published by pickit2, but shares the same capacitor to snub both triac and optotriac thus saving one HV capacitor. I include a schematic (in this case for very light loads, but values were tailored for 1/2 to 1 HP async single phase motors and I lazily duplicated them in this design).
BTW: even "snubberless" triacs perform better with a snubber network.

3) It's not this issue, but when driving an async motor with two of such circuits may be that accidentally they fire toghether, shorting the motor phasing capacitor (that could range from 4 uF up to 25 uF and more, depending on motor characteristics). Triacs are very robust devices and they can whithstand up to ten times the rated current for half an AC mains cycle (i.e.: up to 120 A for BTA12-600), but they are destroyed by the huge dI/dt that occurs initially when the capacitor is short circuited. To protect them from the initial current rising too fast, I found that a small 33 uH / 2 A coil in series between each triac and the load is sufficent to smooth the very first rise of the current before saturating, thus saving the triac. These small coils are not shown in the included schematics.

[PeterMcMonty]

Another suggestion: if the noise of the fan motor, complained by localcrack, is due to the triac switching, rather than cycle partialization you can do cycle skipping: use MOC306x optotriac with zero crossing (as in my schematics) and a zero crossing detector (D1, D2, R25, R26, R27 and Q5 in my schematics) to drive the optotriac N over M cycles (N < or = to M).
Transistor Q5 is on (and its collector is slightly above GND) when AC mains approaches zero volts until it rises agani by some few volts of opposite polarity.
By adjusting R26 and R27 values you can adjust the pulse width at Q5 collector: when the microcontroller detects this signal going down it can drive or not the optotriac, depending by the duty cycle selected; the drive pulse can be removed when the signal returns high: the more precise zero crossing circuit, internal ti the optotriac does the rest of the job.
This signal may also be used as a rather accurate real time clock for the microcontroller.
Of course a pull-up resistor is needed at Q5 collector: this may be the internal pull-up of the microcontroller input or an external resistor.