I want to ask you about a situation which i couldnt find the exact solution or better way to do the job. The situation is i have 3 phase (380V) induction motor and one of the phases to the motor had a switch and the rest two phases and the the phase after the switch goes to conductors and then to ac induction motor, what i want is how can i make a circuit to actualy count if the switch is on/off and if the switch is on but also detect the power outage

One idea for me to use opamp for the phase after the switch to count if the switch is on/off and one opamp before the switch if there is power in the phase but im not sure if i can do these with only one phase of 3 phase system

And another idea while i was looking to some similar questions is directly connecting the phase after the switch to the pic controller with a high resistance to verify if switch is on or not and again the same before the switch if there is power or not

Any ideas, or links or just a way for me to overcome this situation?

btw the switch is a push once switch i actually dont know the exact name but what it does is when you push, it closes the circuit and when you push it again, it opens the circuit.

  • \$\begingroup\$ i really dont understan why people under vote questions here, guys if you have any idea just write something meaningfull for the op and the community. For me building something is the hardest but critizing is the easiest, im not an Electrical Engineer, but trying my best to understand what i can do with my knowledge.... \$\endgroup\$ – Osman Köse May 8 '13 at 13:30

If I'm interpreting your question correctly it sounds like you want to sense the presence of AC voltage at 2 points. One point is the main supply, the second point is after a switch.

You could use a resistor voltage divider to reduce the voltage to a level you could measure with a PIC, then a series diode to remove the negative half wave. The computer I'm on right now doesn't let me run the schematic editor. I can try to add one some time later, if you need.

Keep in mind that 380V AC will KILL you if you make a mistake. If you don't have experience working with electricity PLEASE seek help from someone who does before you connect anything!

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