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120 volt timer

Discussion in 'General Electronics Discussion' started by Ron52, Jun 23, 2017.

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  1. Ron52

    Ron52

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    Jun 23, 2017
    I would like to buy or make a timer that would run a load of approximately 10 to 40 watts off of a 120 volt inverter for anywhere from 20 seconds to a minute. The timer would have to reset automatically when it loses power and when energized it would run for anywhere from 20 seconds to a minute. I am a novice. Thanks
     
  2. Bluejets

    Bluejets

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    Oct 5, 2014
    What control voltage and what power loss is it detecting?
     
    Ron52 likes this.
  3. Ron52

    Ron52

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    Jun 23, 2017
    Thanks for responding and please excuse my ignorance with electronics. I have a GFCI receptacle hooked up to my RV trailer 300 watt pure sine inverter producing 120 volts and running on the 12 volt batteries. The inverter needs a minimum of 8 watts to activate power so it won't allow the GFCI to reset. If I bypass the GFCI receptacle with a load of 8 watts or more then the inverter has power available and I can reset the GFCI receptacle to use it. I don't want the start up load to continue to waste power when I do reset the receptacle so I would like the timer controlling the start up load to quit after a few seconds. I only need a few seconds to reset it but it isn't critical if that load does run for even a few minutes. This will be used when I am not on shore power and I just have solar to recharge batteries. Hope this explains your question. So the control voltage needs to be 120 volt I believe.
     
  4. Bluejets

    Bluejets

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    Oct 5, 2014
    mmm...well, I have drawn out a layout of what you outlined in an attempt to try to find out just exactly what it is you are trying to achieve.

    Firstly, the safety switches we use do not need any potential to set or reset. Perhaps yours does, just I have never seen one in domestic use, so perhaps a link to that would help.

    Secondly, I have no idea why you find it necessary to run an inverter output through a safety switch to begin with as the inverters are mosly not referenced to earth on the output.

    Thirdly, is this the solar connection as shown and again, what are you trying to achieve.

    Hope you are not trying to pump power into a load while connected to shore power.

    Perhaps take a look at the sketch I added and see if this resembles your outcome and perhaps add/ modify it to suit as I said before.
     

    Attached Files:

  5. Ron52

    Ron52

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    Jun 23, 2017
    Thanks for taking the time to help me. Your diagram is accurate to what I'm trying to achieve and the bypass timer would run at least an 8 watt load hopefully for at least 20 seconds but not any longer than needed thus 20 seconds would be ideal. My whole aim is for safety on an outside outlet on the RV trailer. I assumed that since the trailer is grounded to earth that there would still be potential for electrocution from some short circuited appliance to ground. If there is no chance for electrocution from an inverter then I will just forget about doing this. I did install the GFCI and it would not reset until I put a bypass load onto the inverter. Once I put a load on ( in my case I just used a light fixture with a 40 watt bulb) then the GFCI would energize and I could use it normally. It would not trip by stopping power however my concern was that if it did trip for some reason then I would have to manually plug in the light bulb again as I don't want to be using the extra 40 watts in this case ( so I unplugged the light) and I was trying to avoid this. Not a big deal but wanted it to be a simple set up for resetting.
    No I am not trying to pump power into a load and the inverter is completely isolated from the trailers 120 volt system. Thanks again.
     
  6. Bluejets

    Bluejets

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    Oct 5, 2014
    Cannot comment on whether or not a safety switch is required or not in your installation as I cannot see it.

    Others may be able to comment as to why the safety device needs power to reset because, as I mentioned before, never seen this type used for domestic use.
    I still cannot see the purpose of your requirement though.

    As for a timer to bypass, it would have to connect your 40w bulb to the inverter output via a relay and the relay activated via a 12v timer circuit as your 120v is not available at any beginning instant if you follow my drift. Then again if the relay is nc then I would still go with the 12v control anyway.

    Therefore probably a basic delay on timer from Ebay for a few dollars would do the job.

    http://www.ebay.com.au/itm/DC-5V-12...hash=item3ae6b3f9fe:m:mNB8XqeeqL8F4cHAC_y5TDA
     

    Attached Files:

    Last edited: Jun 24, 2017
    Ron52 likes this.
  7. Ron52

    Ron52

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    Jun 23, 2017

    Thanks for your great support! I think I understand what you are getting at and looking at your delay timer it makes sense that would work. If I can access this timer then I will use the 12 v control as suggested.

    I believe the GFC receptacle needs power to reset itself after it trips but it uses less than 8 watts to reset thus the inverter won't supply the necessary power. Does that make sense? No need to reply and I really appreciate your help with my problem.
     
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