3 phase power supply detector.

[KeepItSimpleStupid]

Now wouldn't something like this: https://www.electro-tech-online.com/custompdfs/2012/07/SS-202.pdf do exactly what you ask and even more?

Three relays, one for each phase and the contacts in series could also detect if 3 phase is present, but it would not tell you much about the quality except that it was below the dropout voltage of the coils. The contacts in series make up and AND gate. If v1 > x+-h1 and V2>x+-h2 and V3>x+-h3 then turn on LED. h1, h2 and h3 are the hysteresis numbers of the coils which aren't exact. x is the nominal pull-in/drop-out voltage.

 

[dougy83]

yusuf, that schem you posted is only for single phase. I've attached the drawing for the circuit I described above. The resistors values are set assuming that the peak optocoupler input current is 20mA.

 

[yusuf]

dougy , which auto-coupler i can use.. and in A , B , C line which is neutral...

 

[dougy83]

>> dougy , which auto-coupler i can use..
A bidirectional input, transistor output optocoupler. e.g. an IL255.

>> and in A , B , C line which is neutral...
none. They are the phase lines.

 

[yusuf]

now also in confusion .... please provide me the complete schematics guys because it is very dangerous to play with AC line.. So before taking risk I want to satisfy my self...

 

[dougy83]

now also in confusion .... please provide me the complete schematics guys because it is very dangerous to play with AC line.. So before taking risk I want to satisfy my self...

Then you should get an electrician to install a commercial unit.

 

[yusuf]

will auto-coupler be damage by adding it directly to the main line with 270k resistor as you have stated above in the post..
because it is main line and it contains high voltage.
Then how can this work friend on high voltage.............

 

[unclejed613]

it doesn't matter what the value of the resistors, he was just showing you what a delta connection is. actually there are two fault conditions for a 3-phase supply when you are running a motor, dropped phase and reversed phase. a dropped phase will not allow the motor to run, a reversed phase (miswiring by getting two of the wires reversed) will cause the motor to run backwards (which can damage some types of machinery). what you really need is something like this: **broken link removed** which monitors the phase voltage and the phase sequence.

 

[dougy83]

So before taking risk I want to satisfy my self...

I guess that way you'd die with a smile on your face...