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I am working on a project to control AC load using TRIAC TRIAC AC control

In normal operation it working complete fine

But when a fan regulator specifically step type capacitor regulator is used in vicinty the TRIAC gets triggered and load connected to it which is CFL flikers

After testing I found following observation

The problem only occurs with capacitor type regualtor and not with TRIAC type fan regulator

so my question is how could I reduce the noise (that as per my knowledge is electrically fast transient correct me if i am worng) from Fan regulator.

Please suggest a way to reduce this noise.

Thank you in advance.

Sunil Sheth
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  • Hey Sunil, were you able to find a solution to this issue. I have a [similar issue here](http://electronics.stackexchange.com/questions/219686/triac-spurious-triggering-issue/). What I believe is that triacs don't perform well with capacitive loads. I think we both are having similar issues. Let me know if you find a solution. – Whiskeyjack Feb 29 '16 at 09:19
  • adding a mov across the TRIAC reduce the flickering around 90% .But still 10% CFL flickers due to noise in entering in MOC. – Sunil Sheth Feb 29 '16 at 14:36
  • hello @Whiskeyjack have you found a way to reduce the noise in MOC i am using MOC3041 – Sunil Sheth Mar 01 '16 at 10:10
  • As far as I know, the noise is affecting triac directly rather than MOC. I am using MOC3021. I have raised bounty on my question. Let's see if someone provides a better solution. – Whiskeyjack Mar 01 '16 at 14:08
  • The problem as two reasons first spurious triggering of triac and moc During my test i confirmed that using MOV spurious triggering of triac is removed but moc still triggers And i am also using the same fan regulator like yours. – Sunil Sheth Mar 01 '16 at 14:16
  • Sunil - I found some app notes regarding use of triacs in extremely noisy environments. Can you drop your email and we can discuss the things out. Probably it will solve both our problems. – Whiskeyjack Mar 03 '16 at 07:01
  • hey mail me at- sunilsheth93@gmail.com – Sunil Sheth Mar 03 '16 at 13:50
  • @Whiskeyjack Hi, I am also facing same issue, are you guys with any success ? I also tried to add opto triac snubber circuit but no success. – Harmeet Singh Apr 21 '16 at 16:32
  • @HarmeetSingh - Use FOD4208 along with BTB16-600BW. – Whiskeyjack Apr 21 '16 at 17:10
  • @Whiskeyjack thankyou very much for replying, ok thats for replacing moc3021, but I noticed if I remove MOC and triac gate not connected to anything, still my connected lamp flickers when I turn ON mains, are you facing the same issue too or now you have no issue at all ? – Harmeet Singh Apr 21 '16 at 17:28
  • @Harmeet - There are two factors here. Spurious triggering of triac and spurious triggering of MOC. When gate is not connected, you are facing the first issue. I think you might be using BT136 or some other mainstream triac. Those are very susceptible to such spurious triggering. Another possibility is floating gate being affected by noise but it has a lower probability. Try using BTB16-600BW once and see. These are snubberless triacs capable of withstanding high dV/dt. Same goes for FOD4208. Use of RC snubber is another tricky business and I wanted to avoid it. – Whiskeyjack Apr 22 '16 at 03:21
  • @Whiskeyjack Me using BTA16-600B was not able to get snubberless version, yes snubberless version has 1KV dv/dt, I also got some link to increase dv/dt value for standard triacs using some external components (http://www2.st.com/content/ccc/resource/technical/document/application_note/76/45/54/02/fe/e2/43/eb/DM00045765.pdf/files/DM00045765.pdf/jcr:content/translations/en.DM00045765.pdf) section 1.4, also found that there are triacs like ACST1035-8FP which withstand 4KV dv/dt, I doubt I get ACST1035-8FP triac from my local. – Harmeet Singh Apr 22 '16 at 07:07
  • Snubberless version is a little difficult to acquire since it's a little costly. China is always a source but it will get costly in terms of courier and customs if you import it. You can check element14 for small quantities but buying from them as an individual hobbyist is real pain. I tried RC snubber but it had other issues. My tubelights were flickering when OFF because RC allows some current to pass. Besides this, increased size due to RC wasn't acceptable to me. I chose to spend money and get better raw components. – Whiskeyjack Apr 22 '16 at 08:10
  • Let us [continue this discussion in chat](http://chat.stackexchange.com/rooms/38720/discussion-between-harmeet-singh-and-whiskeyjack). – Harmeet Singh Apr 22 '16 at 08:27
  • @Whiskeyjack Hi, I have got FOD4208 with BTA208S-800B, both have high dv/dt but still facing the issue, can you help ? – Harmeet Singh Sep 28 '16 at 07:51
  • @HarmeetSingh - Is it possible for you to get FOD420 and BTB16-600BW. That's the exact setup I am using without facing any issues. I just checked the datasheet and I feel that FOD4208 will work in place of FOD420 comfortably. Here is the exact schematic that I am using: http://imgur.com/a/zvrO9 – Whiskeyjack Sep 28 '16 at 10:03
  • @Whiskeyjack Thank you very much for replying :), will my combination of triac and optocoupler work, if you can provide your skype id ? – Harmeet Singh Sep 28 '16 at 11:19

1 Answers1

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You are not "worng". It is most likely that either the opto-triac or, more likely, the BTA16 is being triggered by a transient from the other electrical device being switched on an off.

Triacs are normally turned on by triggering the gate, as in your schematic. They can also be turned on by high \$\frac {dV}{dt}\$ across their terminals and the transient could supply that. The datasheet lists in its features

High Immunity to dV/dt - 1500 V/μs minimum at 125°C. (Page 1.)

Minimizes Snubber Networks for Protection

Despite the snubber comment it looks like you need one. A simple RC type would suffice. Make sure it's rated for your mains voltage. (i.e., Don't expect a DC capacitor to last very long!)

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  • Thanks for reply , i tried using snubber circuit but it give rise to another the problem ,during off state the cfl flickers due to leakage current from from snubber circuit can u recommend a way to minimize this leakage current. – Sunil Sheth Feb 27 '16 at 02:37
  • I prefer to use a filter circuit for mains to reduce the fast voltage transient. – Sunil Sheth Feb 27 '16 at 02:45