Connect with us

Thyristor as a triac

Discussion in 'Power Electronics' started by Ramesh Adhikari, Apr 6, 2018.

  1. Ramesh Adhikari

    Ramesh Adhikari

    2
    0
    Apr 6, 2018
    Hi, I have a thyristor with the connection as in this thyristor and i am trying to use it as a traic. So i shorted terminal 2 and 3. terminal 1 and 7 are already connected as in this thyristor.Also i have shorted both the gate (4 and 6).Now i want it to act as a traic with terminal M1(7) and M2(5) and gate(wire that has connected 4 and 6). Will this work?

    Problem: When i simply gave supply to 7 and 5 with a blub connected between them(no pulse signal to gate) the blub glow. Then I checked the individual gate terminal with my tester i saw a phase indication present in gate terminal 4. That was causing the blub to glow. But i expect no phase indication in both gate since i want it to be controlled through my pulse signal. What actually is happening in this case and how can i solve it? Note my connection is same as in second picture.Thank you. Thyristor-Diode-Power-Module-Easy.jpg
    triac-equivalent-function.gif
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,219
    2,695
    Jan 21, 2010
    You will require a different polarity signal to turn on one scr vs the other. (I.e. in a single, but different quadrant for each).

    In contrast, triacs can often be triggered in 4 quadrants.
     
    Ramesh Adhikari likes this.
  3. WHONOES

    WHONOES

    741
    153
    May 20, 2017
    You have to drive each gate individually. The best way and also get galvanic isolation is to use a small pulse transformer between gate and cathode. This will also allow you to get the opposite polarity required. Sometimes, the trigger pulse is constructed as a series of pulses for the required conduction period. This ensures that each half of the circuit will remain on for the conduction period.
    Alternatively, an opto-isolator could be used in a similar fashion. This has the advantage that energy from the SCR circuit will not be reflected back into you drive circuit.
     
    Ramesh Adhikari likes this.
  4. Ramesh Adhikari

    Ramesh Adhikari

    2
    0
    Apr 6, 2018
    Thank you so much, Will this connection work? pulse trer.jpg
     
  5. WHONOES

    WHONOES

    741
    153
    May 20, 2017
    A proper circuit diagram will be more illuminating.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-