Thyrister heat up problem

Discussion in 'General Electronics Chat' started by all4here, Sep 1, 2010.

  1. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0
    now i am using this circuit after the 5 mint the thyristor is heat up too much.

    load is approximate 1 Ampere (using a 200 watt bulb )

    but the capacity of the thyristor is 15 A.

    i am very woried about this plz solve this problem.

    see the attechment for circuit
     
  2. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    Why do you choose to omit the additional parts recommended by the manufacturer?

    [​IMG]
     
  3. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0

    i think this is not important but i will try it plz tell me the capacitor type and voltage of the capacitor and 39 ohm is a 1/4 watt ?
    i think we apply the 2.6 v which is not sufficient to operate the moc.
    what is your suggestion about this ?

    now i agian add the pic and mention the wattage of the resister plz check it
     
  4. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0
    i personaly lot of think that causes the problem


    1-the value of resister is not perfect
    2-the input volt of moc is not sufficient


    plz senier member help me about this problem
     
  5. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Those components form a snubber circuit which is often necessary for relaible switching. Another question would be do you have it mounted on a heat sink? SCRs are far better than BJTs but still have some internal resistance and create heat as current is passed through them.

    How much? The spec sheet should give you some ideas.
     
  6. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0

    yes i have use the heat sink but the heat is too much and increase with respect the time.ok i will try to use the snuber circuit.plz tell me the capacitor voltage.
     
  7. timrobbins

    Active Member

    Aug 29, 2009
    318
    16
    Ho do you know the thyristor is overheating??
     
  8. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0

    after 5 mint when i touch the finger to the heat sink it is too much hot.
    i can not stay the finger for 2 second becuse it was too hot
     
    Last edited: Sep 1, 2010
  9. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    You can use 39Ω 0.5W resistor and a 0.01uF 600V capacitor.

    The MOC3041 is a zero-crossing opto-triac and requires at least 15mA to trigger(15mA to 60mA) so I would pick 25mA as operating current. Thus the series resistor value becomes 47Ω for 2.6V instead of your existing 100Ω.

    The Q6015 is big TRIAC family with many variations. You would need to give us the exact part number lettering as shown on the TRIAC package. e.g. Q6015LT5..
     
  10. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0

    part number is Q6015L5
     
  11. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    OK.

    Since Q6015L5 is not a sensitive gate TRIAC, the gate resistor to MT1 is not really needed. In fact having it will even degrade the zero crossing triggering and resulted in a phase control instead.

    [​IMG]
     
  12. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0


    SIr i have make the circuit and also add pic.plz check it.

    but the problem is still there

    the therystor is heatup tooo much .

    i get a 0.15 mA on gate. is it enough ?


    plz consult the pic
     
  13. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    How do you know?

    Did you place a DVM in series with the gate? The gate current is actually some pulses happening at every zero crossing. You can only get their amplitude via looking at an CRO trace.

    Don't try that because probing live circuit with a CRO is very dangerous.

    My other suggestion is to switch to a different TRIAC of the same voltage and current rating to see what happens.
     
  14. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    Hi all4 here - Are you able to measure the total AC voltage across the triac [MT1 to MT2]?

    Even probing with a multimeter you need to be careful - 240VAC can be lethal.
     
  15. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0
    yes i use a DVM in series.
     
  16. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0


    this is correct.its equal to main line which is 220 V AC
     
  17. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    What is the AC voltage between MT1 & MT2 when the lamp is ON, i.e. the TRIAC Q6015L5 is made conducting by passing 26mA in the IR LED side of the MOC3041M?
     
  18. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0

    yes each and every thing is ok.but the problem is thyristor is heat up too much.i also try the BT137 but same problem they also heat up.plz guide me i am too much woried.

    why the thyristor is going to produce the heat.
     
  19. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0


    eblc plz tell me the capacitor of .01uf 600 v is a polar capacitor or non polar capacitor?
     
  20. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    What is the AC voltage between MT1 & MT2 when the lamp is ON?

    This is the third time the same question is being asked and you don't seem to have an answer.

     
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