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I have this schematic using TRIAC BT136 600E, and MOC3023.

enter image description here

I want to control a contactor with a coil voltage of 380 V. The problem is that the TRIAC works without receiving a command from me, so it passes the electric voltage by itself (TRIAC ON).

What I can do for this problem please?

I use another TRIAC + MOC but the problem still.

enter image description here

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    \$\begingroup\$ Can you describe the problem better? \$\endgroup\$
    – Voltage Spike ♦
    Commented Jul 16 at 23:55

2 Answers 2

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You will need parts rated for at least 600V and preferably more like 800V or 1kV to reliably switch a 380VAC load, more because it's inductive (a relay coil). You may need a snubber and/or MOV across the relay coil if it does not turn off after you've commanded it on, but if it is turning on without command, that suggests inadequately rated parts (the triac and/or the opto).

Most MOC3023 parts are rated at only 400V which won't even handle the 540V peak of a 380VAC RMS supply. Peak is \$\sqrt{2}\$ times RMS value.

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  • \$\begingroup\$ Thank you for replaying, I change to Triac and Optocoupler to this Series : Triac BTA 225 800B + MOC 3083, The problem still exists because the triac passes the electrical charge, which causes the contactor to operate without me giving it the command first. It takes the command automatically. Is the problem in the installation or the problem in choosing the values ​​of the resistors? \$\endgroup\$
    – OUSSAMA LACHHAB
    Commented Jul 17 at 10:17
  • \$\begingroup\$ To troubleshoot it, remove the resistor (no connection) and see if it still turns on. If it does, then the triac is the problem. \$\endgroup\$
    – Spehro 'speff' Pefhany
    Commented Jul 17 at 12:52
  • \$\begingroup\$ Okay I will try this and I give you some feedback \$\endgroup\$
    – OUSSAMA LACHHAB
    Commented Jul 17 at 16:56
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Triac works on different quadrants. If the triac works all the time 380VAC always coming to the triac gate and T1. Try to put resistor to the gate pin. Also the other thing that, how do you enable optotriac? Maybe you are activating LED all the time.

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  • \$\begingroup\$ My optotriac still OFF all time without receiving any command On her LED, the question : does this idea work with 380V ??? \$\endgroup\$
    – OUSSAMA LACHHAB
    Commented Jul 17 at 16:54

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