help with solid state relay

[keron]

hello all,
                  i want make a solid state relay using MOC 3041 opto coupler triac driver and BTA 24 triac.i tried the circuit in data sheet of MOC 3041 but it is not working >.
                        the circuit i used is given as attachement.i want to switch a 1HP induction motor using solid state relay,supply volt 230v.current comes to <4amp.
please give suggestions.

 

[ante1]

Hi keron,

The circuit is not complete; here is how I've used the MOC3041 to switch a transformer. http://www.electronics-lab.com/projects/power/036/index.html
The mains circuit part of this project should work for any inductive load.

 

[keron]

hello Ante,
                 that 330ohm resistor between triac gate and terminal i have used but omitted in the circuit diagaram sorry.but someof the data sheets says u need such  a resistor between gate and terminal when you use sensitive gate triac.what do you say about that?.
                                    the snubber circuit consisting of 47 ohm and 240v,0.33 uf caps also i have used.but not shown to make circuit simple.
                                           only doubt is, i used supply from the battery of 9V to experiment with MOC3041.(TO SWITCH ON AND OFF).does this optocoupler need some kind off pulsed signals?iam not sure about the term i have used.wont this circuit  switch on and off when i connect and disconnect manualy from the battery source?.
                                    i have soldered the terminals wrongly at first trial.that is i connected mains to gate thinking its MT1.and gate was connected to pin 6 of moc.i have changed the triac after that but not MOC 3041.moc might got damaged by that?may be that is a cause iam not sure...                       thanks for the reply

 

[audioguru2]

Your triac needs 50ma on its gate, not only 15ma. Why not more, maybe 70mA?

 

[keron]

hello guru,
               but the datasheet specifies that current in MOC 3041 triac DRIVER  LEd should be limitted.the value is 15 mamp..the circuit in previous reply by ante also shows the current limiting resistor in pin1.
                                                            how to provide 50ma to triac gate ?

 

[audioguru2]

hello guru,
               but the datasheet specifies that current in MOC 3041 triac DRIVER  LEd should be limitted.the value is 15 mamp..the circuit in previous reply by ante also shows the current limiting resistor in pin1.

The datasheet for the MOC3041 says that an LED current of 15mA will trigger all of them. It is the minimum LED current. If your resistor value is 5% high then some MOC3041's won't trigger. The datasheet recommends using an LED current between the minimum of 15mA and the maximum of 60mA. Ante's circuit uses 32mA.

how to provide 50ma to triac gate ?

Use a low value resistor so that the triac turns on near zero crossing. The gate voltage is about 1.0V so when the AC peak voltage is 3.8V then a 56 ohm resistor provides 50mA.
The minimum value is 19 ohms because the MOC3041 has a max AC peak trigger voltage rating of 20V and its max current is 1A.

 

[keron]

thanks guru,
                      so for my application switching a load of 400-500watts in 220volt A/C(SUPPLY VOLTAGE VARIES FROM 160-220VAC) induction motor (in water pump for example).
Please suggest resistor values for the triac gate. 50ohms will do.or a smaller value needed?
330ohms resistor between gate and MT2 needed?
does changing MT1 and MT2(terminals)affect circuit by any means?
does the LED in MOC need a pulsed signal.or it will work from any  std dc voltage(as in turning on a small DC switch)?

 

[keron]

thanks guru,
                      so for my application switching a load of 400-500watts in 220volt A/C(SUPPLY VOLTAGE VARIES FROM 160-220VAC) induction motor (in water pump for example).
Please suggest resistor values for the triac gate .50ohms will do.or a smaller value needed,?
330ohms resistor between gate and MT2 needed?
does changing MT1 and MT2(terminals)affect circuit by any means?
does the LED in MOC need a pulsed signal.or it will work from any  std dc voltage(as in turning on a small DC switch)?

 

[audioguru2]

Please suggest resistor values for the triac gate .50ohms will do.or a smaller value needed,?

0.5 ohms is nearly a dead short. The MOC3041 will blow up! Use 47 ohms.

Is 330ohms resistor between gate and MT2 needed?

Yes, it turns off the triac.

does changing MT1 and MT2(terminals)affect circuit by any means?

The triac won't work if MT1 and MT2 are reversed.

does the LED in MOC need a pulsed signal.or it will work from any  std dc voltage(as in turning on a small DC switch)?

Use DC from about 3V or more to turn on the LED through the current-limiting resistor.

 

[keron]

it was 50ohms itself.thank you very much.let me try this out.
one important thing,BTA 24  will serve my purpose rt?load is not that heavy i guess for BTA 24 600CW.
http://www.st.com/stonline/products/literature/ds/7470/bta24.pdf
i think A1 and A2 in datasheet is same as  MT1 and MT2 ?in the diagram by ante MT1 connected to pin 6 through 50ohms resistor rt?
quarter watt resistors will be sufficient,or do i need to use 1watt or something like that or 50ohms and 330ohms.
finally MOC 3041 can be used to switch  this triac rt?
if iam using 9volt supply what should be the value of current limiting resistor?
what are the possible mistakes  by which we can damage MOC 3041 or triac(like connecting gate of triac to mains )?

 

[audioguru2]

One-quarter Watt resistors will be fine.

The semiconductors are seriously damaged if you look at them too hard. ;D

 

[keron]

guru,i gues you  have answered yes to all of my questions.thank you..i will take care to not look at it hardly..lol