AC Voltage Detector/Switch

Discussion in 'General Electronics Chat' started by masa6614, Nov 3, 2016.

  1. masa6614

    Thread Starter Active Member

    Nov 9, 2008
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    0
    Hello,
    I'm having trouble locating a device that in my mind should be something commonly available in industry. Maybe I'm using the wrong types of search terms, so hopefully you can help or point me in the right direction.

    I've got a component in my system that requires 110VAC, however, the system is meant to be used around the world, so places where wall power can vary from 110VAC to 220VAC, as well as in frequency. I've contacted the manufacturer and they told me the component will work as long as the voltage is around 110VAC, and that it won't work with 220VAC, but it can handle 50-60Hz. I am unable to place a manual toggle switch on the system where the operator can select an expected input, and in turn, have the power routed through a step down transformer if its for 220V.
    So is there such a device that automatically does this detection with an electronic output? Alot of my searches turn up "voltage detectors" with visual meters. The only other searches which turned up anything useful are circuit schematics using discrete electronic components (resistors, caps, ICs, etc). I don't have the luxury of spinning a board or breadboard, this is for an commercial system.
    So I'm hoping for some nicely packaged DIN-mount type module which detected the voltage level. If it had internal switches that routed each voltage range a certain way that would be even better, but even if it just had a discrete output or something I can use to control a relay to a transformer that helps.

    Thanks for any help!
     
  2. #12

    Expert

    Nov 30, 2010
    18,076
    9,691
    I'm thinking a 240 VAC relay might be rigged so that 120 VAC isn't enough to activate it.
    Some relays just won't work at half voltage, and some will. That's why I used the word, "rigged". You might need a resistor to deaden the response of a 240 VAC relay so it won't trigger unless it gets at least 150 to 200 volts.

    This is not the right relay, but the datasheet says the, "must operate" voltage is 85% of its rating.
     
  3. masa6614

    Thread Starter Active Member

    Nov 9, 2008
    48
    0
    Thanks. I was able to find something along those lines that I'm sure I can make work, a VWKE voltage monitor relay, that has an undervoltage and uppervoltage monitor which controls a relay.
     
  4. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
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    Not cheap, but if of-the-shelf and DIN are important, it looks like the way to go.

    ak
     
  5. Externet

    AAC Fanatic!

    Nov 29, 2005
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    Did that by myself a while ago...
    A neon bulb with a proper resistor, superglued to a phototransistor; as I was unable to find a neon optocoupler in the industry. All inside a piece of black shrink tubing. Worked perfect, and isolates mains. Can be packaged in epoxy or whatever if needed.
     
  6. Externet

    AAC Fanatic!

    Nov 29, 2005
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  7. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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    When the device is switched on, initially the voltage detector will be in the 'low voltage' state and will switch to the 'high voltage' state sometime later if it is a 230V supply. That means that for a period of time the 110V equipment will receive 230V - oops!

    So such a system need to either disconnect the supply completely until its voltage has been established, or have a default setting of 230V until the voltage has been stable at 110V for a little while and then switch to the 110V setting.
     
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