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Oring mains with triacs

Former Member

Hello everybody,

 

I need to supply a load with 2 different ways.

Each way is the 230V 50Hz mains through a switch (a triac on or off for a few seconds).

Thus it is a system in wich a sequencer outputs mains 230V through ouput 1 or output 2 (they have the same phase, because it's the same power before switch).

 

I have to power another system with both outputs without wiring them together.

I first tought to use 2 triacs in parallel, each gate and anode to the respective output, and the cathodes wired together to feed to the load.

The load is then connected to the neutral for the return.

 

When 1st output is on, the respective triac is on and the load too, that's ok.

The problem is that I'm able to detect the power through the 2nd triac wich is off (on its anode).

I tried different gate circuits : different resistor values, w or w/o diac, w or w/o capacitor to cathod.

Each time I have a parasitic voltage on the 2nd triac anode.

 

Of course the problem is the same if 2nd triac is on and 1st is off.

Each is polarised in quadrant 1 and 3.

The load is only 30W.

 

 

BTW : I can't use electromechanical relay.

 

Does anyone have an idea ?

Thank you

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  • 0

    What you call the parasitic voltage on the other anode is probably a small leakage current through a capacitor. It is no problem and a second power source will never notice it.  The circuit should work just fine.  What happens if you turn on both scrs at the same time?  Even that should be no problem even if the ac is a different frequency. I suppose the load is a resistor or a motor.

  • 0 in reply to WVPhysicist

    Hi,

    Thanks for the answer.

    The goal is to create a OR function with 2 or more mains sources.

    Only 1 source is active at the same time, the other inactive sources measure the remaining voltage on their lines and it has to be almost null, eslse a default is generated.

    The load is a resistor.

    I think internal parasitics capacitors may start a bloqued triac, when the other tric changes the reference voltage of its anode (because they're tied together to the load).