Knowledge about Triac

Discussion in 'General Electronics Chat' started by Iodem_Asakura, Mar 23, 2005.

  1. Iodem_Asakura

    Thread Starter Senior Member

    Sep 14, 2004
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    Hi everybody.

    Does anyone have some page where i can find information about Triacs?

    I need all the information possible. Including how to design an snubber for it.

    Thanks for your help
     
  2. hgmjr

    Moderator

    Jan 28, 2005
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    Triac Application Note

    iodem_asakura,

    Here is a link to an application note covering the general topic of triacs. It is located on Motorola's On-Semiconductor website. The application note should give you a good starting point. Once you digest the app note you can look at the specs on some of the specific triacs located on the same website to further you knowledge.

    Good Luck.
     
  3. Iodem_Asakura

    Thread Starter Senior Member

    Sep 14, 2004
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    0
    Thanks man, it seem really complete.
    I'm going to eat it now ;) . And later do what you suggested me, look some triac datasheet.
    Sorry for replying so late, i had some troubles. :p
    Really thanks
     
  4. hgmjr

    Moderator

    Jan 28, 2005
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    Glad I could help you get starrted in your investigation into the topic. Be sure to keep us in the loop as you develop your design.
     
  5. Iodem_Asakura

    Thread Starter Senior Member

    Sep 14, 2004
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    I sas looking the application note for a while and saw that they focus on connecting triacs in serie to achieve greater voltaje support.

    But what i need is great current support. The triac i got support a max current of 40 Amps, so i thought i can use it to supply maybe 30 Amps to ensure Triacs life. Though, i want to supply at least 50 Amps from 120 Vac, so i was thinking of putting two triac in parallel. But i'm not sure if that is going to works. :huh:

    Have you something that can help? I'll be glad for your advices.

    Thanks
     
  6. hgmjr

    Moderator

    Jan 28, 2005
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    I too had no luck locating a triac rated above 40 Amps.

    I think the problem with trying to operate two triacs in parallel is getting the two devices to trigger simultaneously. I don't think these devices are intended for parallel operation anyway.

    Triacs are typically used to control ac powered devices (for example, an ac motor) by regulating the energy delivered to the load through the reduction of the "area under the curve" of the sinewave by truncating a portion of both the positive and negative half-cycles on a cycle by cycle basis while still maintaining the peak-to-peak voltage of the ac sinewave.

    Is that the way you understand them to operate? Is that how you are planning to use the device?
     
  7. buddyengineers

    Member

    Mar 19, 2005
    26
    0

    Well jst adding up something may or maynot be related to the discussion.., but read ur query at least.., As far as my knowledge goes.., never used a triac., but always used two SCR's in antiparallel mode with gates connected.., hav seen them in use at many places., they give more current handling capacity as compared to a triac..,

    the combination is used in an RF Shield case.., to prevent interference.., thts how i can help u.., anyways if found out anythng else..,will surely let u know...,

    Cya
     
  8. Iodem_Asakura

    Thread Starter Senior Member

    Sep 14, 2004
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    That is what i was thinking, the first problem in putting triacs in parallel it's they are not going to trigger at the same time. I don't think i can allow that to ocurr. What i need to do is connect or disconnect a load from the AC line (120 Vac), just the same way i can do with relay, but i don't want to use relays. I don't need to control the shoot angel, only connect or disconnect the load.

    About the SCR i really don't want to use these, cause that will make the design more complex (if don't think so, let me know why). I'll leave they for the last oportunity, meanwhile i want to try working with triacs.

    Anyway, have you some datasheet of a SCR that support at least 70 Amps?
     
  9. mozikluv

    AAC Fanatic!

    Jan 22, 2004
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  10. Iodem_Asakura

    Thread Starter Senior Member

    Sep 14, 2004
    140
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    Thanks for the datasheet, but i want something smaller (yes, i know i'm being a bit demanding, maybe i won't find what i'm looking for, but at least i'm trying).

    Perhaps i'll use the 40 amps rated triac after all. But thanks for all your help guys.
     
  11. hgmjr

    Moderator

    Jan 28, 2005
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    Iodem,

    I may be totally out in left field but see if this makes sense.

    What if you take a 2 to 1 step-up transformer and boost your AC input from 110 Vac to 220 Vac. The power-in will equal the power-out and you will have twice the Voltage at half the current. Of course you will have some transformer efficiency loss but that should be low. Then you can use your 40 amp Triac to process the 220Vac and then step it back down using a 2 to 1 step-down transformer.

    It seems as though this would address your triac limited current capacity problem. The transformers may end up being hernia generators :D . This may violate your "keep it small" mandate.

    Its not pretty but it might just work.
     
  12. Iodem_Asakura

    Thread Starter Senior Member

    Sep 14, 2004
    140
    0
    Wow, i hadn't tought that. That's a great idea!!

    But, you're right that violate my "keep it small" mandate. But i'll think it a bit more. Thank you for your excelente idea. That is a good solution.
     
  13. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    You are very welcome.

    Good Luck.
     
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