How to detect 3phase...

[panic mode]

that is connector or terminal block, for you to bring wires to the circuit board.
1 = +5..6V
2 = GND
3 = relay NO (normally open, "phases ok")
4 = relay common
5 = relay NC (normally closed, "phases not ok")

 

[alec_t]

Here's a possible circuit. When it detects both the presence and the sequence of the 3 phases are ok the relay pulls in and one pole operates the motor start switch. If any phase is missing or the sequence is incorrect the relay drops out and the other pole operates the motor stop switch.

 

[yusuf]

here's a possible circuit. When it detects both the presence and the sequence of the 3 phases are ok the relay pulls in and one pole operates the motor start switch. If any phase is missing or the sequence is incorrect the relay drops out and the other pole operates the motor stop switch.

thanks alec...

Can i use "pc817" auto-coupler in place of " cny17-3 "..
And what is the values and wattage of d1,d2, d3 which is connected across auto-coupler..

IF 3PHASE SEQUENCE IS CORRECT THE MOTOR STARTS OK!
BUT WHAT WILL BE THE RESULT IF IN BETWEEN THE 3 PHASE DISAPPEAR ... ???

AND FROM WHERE I SHOULD GIVE THE POWER SUPPLY TO CIRCUIT TO WORK ..

IF SUPPOSE I USED 9V BATTERY , THEN HOW LONG IT WILL LAST..

 

[yusuf]

that is connector or terminal block, for you to bring wires to the circuit board.
1 = +5..6v
2 = gnd
3 = relay no (normally open, "phases ok")
4 = relay common
5 = relay nc (normally closed, "phases not ok")

thanks friend...

Can i use "pc817" auto-coupler in place of "sfh620-3" ..

And please once again , can you explain in brief how your circuit is working by showing on schematics..

Thanks again

 

[alec_t]

The type of opto-coupler is not critical. A PC817 is fine.

BUT WHAT WILL BE THE RESULT IF IN BETWEEN THE 3 PHASE DISAPPEAR ... ???

The relay will drop out and the contacts across the 'stop' switch will close to stop the motor. You would need additional safety components to prevent the motor starting up automatically if power was restored; it should restart only under manual control.

IF SUPPOSE I USED 9V BATTERY , THEN HOW LONG IT WILL LAST.

That depends mainly on the type of relay used and its coil current. It probably wouldn't be many hours.

 

[panic mode]

sfh620 is AC opto, it has two LEDs so output is active for both positive and negative duration of AC wave.
there is a small pause in signal when wave is at or near zero. for example duty cycle of pulse train is somewhere about 90%.

pc817 is DC opto with single LED so output is active only during positive portion of AC wave (or little bit shorter).
the pause between pulses would be longer. duty cycle of pulse train is somewhere about 45%

you can use either and if you have problem with relay chattering increase C1 value.
period in 50Hz AC is 20ms. one half period is 10ms which is also approximate time of relay to turn on or off.
the other way is to latch signals like in circuit posted by alec_t

 

[yusuf]

The type of opto-coupler is not critical. A PC817 is fine.
The relay will drop out and the contacts across the 'stop' switch will close to stop the motor. You would need additional safety components to prevent the motor starting up automatically if power was restored; it should restart only under manual control.
That depends mainly on the type of relay used and its coil current. It probably wouldn't be many hours.

And what is the values and wattage of d1,d2, d3 which is connected across auto-coupler..

THANKSSSSSSSSSSSSSS

 

[yusuf]

sfh620 is AC opto, it has two LEDs so output is active for both positive and negative duration of AC wave.
there is a small pause in signal when wave is at or near zero. for example duty cycle of pulse train is somewhere about 90%.

pc817 is DC opto with single LED so output is active only during positive portion of AC wave (or little bit shorter).
the pause between pulses would be longer. duty cycle of pulse train is somewhere about 45%

you can use either and if you have problem with relay chattering increase C1 value.
period in 50Hz AC is 20ms. one half period is 10ms which is also approximate time of relay to turn on or off.
the other way is to latch signals like in circuit posted by alec_t

And what is the values and wattage of d1,d2, d3 which is connected across auto-coupler..

IF SUPPOSE I USED YOUR CIRCUIT WITH 9V BATTERY , THEN HOW LONG IT WILL LAST.

THANK YOU VERYYYYYYYYYYYYYYY MUCH AGAIN...

 

[alec_t]

And what is the values and wattage of d1,d2, d3

Almost any silicon diode will do in my circuit, e.g. 1N4148, 1N4001 etc. Wattage is negligible.

9V BATTERY , THEN HOW LONG IT WILL LAST.

PLEASE DON'T SHOUT! See post #25. And as a reminder see the warning about safety components.

 

[yusuf]

OK ALEC !

FROM WHERE SHOULD i GIVE THE POWER SUPPLY TO THIS CIRCUIT TO WORK..

 

[alec_t]

YOU'RE STILL SHOUTING!
You can get the power from any one of the phases, via an isolating transformer.

 

[alec_t]

Here's a revised circuit. The main change is the use of a further latch U5b to prevent the motor re-starting automatically if a phase is lost then re-appears. A button has to be pressed manually to start the motor via a contactor. U7 and associated components have also been added so that latch U5b will be reset if the contactor's 'stop' button is pressed, e.g. in an emergency. This part of the circuit depends on the contactor having some means of feeding back a mains-voltage signal. If such a signal is unavailable the circuit will need some other means of detecting that the stop button has been pressed.

 

[yusuf]

Alec circuit is working ............
I have attached led to each phase..
But the problem is...
If any (phase a,b ,c) phase disappear the connected led stills glows..
I have given neutral to the circuit from the ground..
Not from the neutral wire..
So , this was a fault.. So i simply connected a mobile charger ...
Strange result occurred...
The phase disappears but the connected charger is still on..
My friend farmer said that the 3-phase line also gives reverse voltage..
But i didn't understood..
Well i have attached the image of how did i connected a simple mobile charger except circuit for just testing...

 

[alec_t]

My circuit was intended for a 3-phase Y-connected 4-wire system (the 4th wire being neutral). Sorry I didn't make that clear.
You should not connect neutral to ground. Neutral should connect only to the opto-isolator inputs, otherwise there is no isolation. In the circuit I posted circuit 'ground' is just the negative rail of the power supply.

I have given neutral to the circuit from the ground. Not from the neutral wire.

If you have a neutral wire why don't you use it as in the circuit I posted?

 

[yusuf]

my circuit was intended for a 3-phase y-connected 4-wire system (the 4th wire being neutral). Sorry i didn't make that clear.
You should not connect neutral to ground. Neutral should connect only to the opto-isolator inputs, otherwise there is no isolation. In the circuit i posted circuit 'ground' is just the negative rail of the power supply.
If you have a neutral wire why don't you use it as in the circuit i posted?

actually the neutral wire is far away from my house..

Friend , can you explain difference between ground and neutral..

And what does neutral and ground do..
And why neutral is necessary ..

For isolation can we use ground..

Thanks again alec...

 

[alec_t]

can you explain difference between ground and neutral

Ground is, literally, the Earth. At the electrical power generating station the neutral (zero volts reference potential) terminal of the generator is connected to a well-earthed point (e.g. buried electrode). But remote from the generator the neutral wire may be several volts different from true earth potential because of stray currents in the wire and it can also have voltage spikes from interference. Isolation of as much of the circuit as possible from mains and neutral wiring is advisable to protect against shock/damage. You can't rely on the domestic neutral being at zero volts; some idiot may have connected wires wrongly at some point in the distribution system, or a cable may have been damaged and shorted.
Here's a circuit variation for a delta-wired system, avoiding the need for a neutral connection. Be aware that the voltage between phases is very high and the resistors and capacitors used at the inputs of the opt-isolators MUST be rated accordingly. These mains voltages are LETHAL. Due care must be taken. If in doubt consult a local qualified electrician.

 

[yusuf]

ground is, literally, the earth. At the electrical power generating station the neutral (zero volts reference potential) terminal of the generator is connected to a well-earthed point (e.g. Buried electrode). But remote from the generator the neutral wire may be several volts different from true earth potential because of stray currents in the wire and it can also have voltage spikes from interference. Isolation of as much of the circuit as possible from mains and neutral wiring is advisable to protect against shock/damage. You can't rely on the domestic neutral being at zero volts; some idiot may have connected wires wrongly at some point in the distribution system, or a cable may have been damaged and shorted.
Here's a circuit variation for a delta-wired system, avoiding the need for a neutral connection. Be aware that the voltage between phases is very high and the resistors and capacitors used at the inputs of the opt-isolators must be rated accordingly. these mains voltages are lethal. Due care must be taken. If in doubt consult a local qualified electrician.

alec thanks for your reply...
I will go once again at my farm and try this circuit..
And i will post the result...

Ok !
Well thanks again..

 

[yusuf]

Friend how should i connect pc817 auto-coupler is place of cny 17-3..
AND I ALSO WANT TO ADD LED AT THE OUTPUT OF AUTO-COUPLER TO INDICATE THE PHASE AVAILABILITY..

 

[alec_t]

how should i connect pc817 auto-coupler

It's an opto-coupler, not an auto-coupler. Pin 1 is diode anode, pin 2 is diode cathode, pin 3 is emitter, pin 4 is collector.

I ALSO WANT TO ADD LED

You're SHOUTING again, unnecessarily.
See the component changes in the dotted-line rectangle in the attached revised drawing. The LED will light only when all three phases are present and in the correct sequence (A,B,C).
View attachment 67745

 

[panic mode]

yusuf,

in case you didn't know it, writing in all capitals (SUCH AS THIS) is considered rude (shouting). please avoid capitals unless your intention is to be rude and offending.