Status of AC appliances

[kanni1303]

Hi,
I need to read the status of the AC appliance (FAN, Light etc) how to read in Digital (On or OFF) is there any sensor to read AC switch status.

 

[BradtheRad]

In general, read voltage across the switch. If you get a reading, the switch is open. However there are appliances which contain two switches: 1 manual, 1 automatic internal. Then the status is difficult to read.

Or do you want to know when the appliance is drawing current? Then you might insert a low ohm resistor, and read voltage across it. Or try to detect a magnetic field around one wire of the power cord. The wire must be a single wire, because if paired then they cancel each other's AC field.

 

[kanni1303]

with simple resitor I could read the voltage. But how can I connect to my Controller, I don't think there is Isolator works on input AC and Output DC can you elaborate?

 

[BradtheRad]

For obvious reasons it's better not to allow high voltage mains AC to reach your microcontroller. An optocoupler/ optoisolator makes a safe detection method.

Each appliance needs to be examined, to find the easiest way to detect its on/off status. It could require that you rearrange wires, or install a junction block, etc.

Does the appliance contain a transformer? Motor? You might detect 'On' status by placing a telephone pickup coil near it. Basically it's a coil consisting of many turns of thin wire. It is sensitive to magnetic flux fields nearby.

 

[Arya Kumar]

Current sensor module are in market . Add it with opam callibrate it in 5 volt and get ur job done

 

[kanni1303]

Ok thanks for your input I will check and get back