Connect with us

Has utility power been restored?

Discussion in 'General Electronics Discussion' started by MultiSync, Sep 19, 2015.

  1. MultiSync

    MultiSync

    1
    0
    Sep 19, 2015
    Need some advice on a photo switch application.

    I have a portable emergency generator that uses an outdoor manual transfer switch.

    The problem is that when switched to the generator setup during a power outage I have no easy means of knowing if or when utility power is restored. The electric utility meter has two status LEDs behind a small clear plastic window that are always ON when power is available. I would like to design a waterproof circuit (9-12Vdc source would be nice) that would use a light sensor that would trigger a relay to sound a small (remote-wired) buzzer and light to let me know (day or night) that power has been restored.

    The LEDs in the meter are red & yellow. I would like to use a photodiode that has a sensitivity rating of 600uM (orange wavelength).
     
  2. duke37

    duke37

    5,224
    718
    Jan 9, 2011
    I saw somewhere that ordinary LEDs can be used to detect light, I think they were used in the reverse bias condition. Some experimentation would be required to see if the wavelengths matched.

    A comparator and device driver would complete the setup. 9 to 12V would be ideal to turn on a FET which could replace a relay.
     
  3. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    648
    May 8, 2012
    Is your KWH meter new generation (Digital) that transmits the data to the utility?

    Chris
     
  4. AnalogKid

    AnalogKid

    2,299
    647
    Jun 10, 2015
    Many photodiodes and phototransistors come with molded on lenses to narrow their detection angle. One of these pointed a one of the LEDs should be reasonably immune to false alarms, particularly if you differentiate (edge detect) the output.

    ak
     
  5. Arouse1973

    Arouse1973 Adam

    5,164
    1,078
    Dec 18, 2013
    Yep, Green LEDs can be used.
     
  6. Arouse1973

    Arouse1973 Adam

    5,164
    1,078
    Dec 18, 2013
    I assume you want the buzzer to sound when power is lost. Otherwise won't it be sounding all the time when you have utility power?
    Adam
     
  7. AnalogKid

    AnalogKid

    2,299
    647
    Jun 10, 2015
    Or enable itself when power is lost, and go off when it returns.

    ak
     
    Arouse1973 likes this.
  8. AnalogKid

    AnalogKid

    2,299
    647
    Jun 10, 2015
    If there is an AC outlet or other direct access to the incoming AC power line before the transfer switch, a fairly simple circuit could sit on the line, arm itself when power goes out, and beep when it comes back - ***without*** a power source to run the circuit throughout the power outage. If fact, IF a small piezo beeper is enough of a sounder, AND IF you are comfortable with building a small non-isolated power supply, THEN the whole thing is pretty simple.

    Another thought - If you have an AC-powered buzzer and an AC-coil SPDT relay, the whole circuit can be done without any active electronics.

    ak
     
    Arouse1973 likes this.
  9. Bluejets

    Bluejets

    3,477
    705
    Oct 5, 2014
    Hack into a no contact volt pen......
     

    Attached Files:

    CDRIVE likes this.
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-