AC Amp Detection and Control

Discussion in 'The Projects Forum' started by RCB, Jan 21, 2013.

  1. RCB

    Thread Starter New Member

    Jan 21, 2013
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    Requesting a schematic for a 110 VAC powered circuit that will activate a relay when a set amperage is detected on a 110 VAC line. The trigger amperage can be adjusted to energize the relay at a set point range between 5 and 25 amps. The relay will remain energized until the amps fall below the set amperage.

    The circuit will be used in a Honda EU200i inverter (generator) to control the eco-throttle switch, which allows the engine to run at a lower speed. The inverter powers an electric motor that runs fine with the eco switch on, but the "kick" of the motor starting up puts the inverter into overload/shut down. The new circuit would detect motor start-up amps and turn the eco switch off until the motor stabilizes at running amps.

    Thank you,
    Richard
     
  2. wayneh

    Expert

    Sep 9, 2010
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    A timer might be simpler to implement. For instance, the switch won't activate for, say, 2 minutes after startup. Would that work?
     
  3. BillB3857

    Senior Member

    Feb 28, 2009
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    To do what you want, you need the crystal ball that can predict the future. It would tell your generator that the motor is about to start, do the throttle thing, wait for the gas motor to get up to speed, then allow the electric motor to start. Are you sure the electric motor isn't simply too big for your generator?

    I have the same generator and simply turn off the eco-throttle function if I know I'll be running high starting current loads.
     
  4. RCB

    Thread Starter New Member

    Jan 21, 2013
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    Wayneh, a time would work fine- whatever would make for a least complex circuit..
     
  5. RCB

    Thread Starter New Member

    Jan 21, 2013
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    Bill, the motor is the compressor of a RV AC that continuously cycles on/off. The Honda manual states the eco switch should kick out with load increase, but my inverter/engine can't seem to rev up fast enough to satisfy the start-up amps.
     
  6. wayneh

    Expert

    Sep 9, 2010
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    I had to read and re-read your's and the OP's posts before I got this. Now I see the problem. My notion of using a timer would only work if you could use it to delay the turn-on of the compressor motor until the generator has come off (or been forced off) of the low idle.
     
  7. BillB3857

    Senior Member

    Feb 28, 2009
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    There are a couple of ways I could see around your problem. One would be to somehow alter the eco-mode RPM. You may be right on the edge of tripping with the starting draw of the AC. Second, do you have the AC fan on all the time or does it start with the compressor? If they come on together, it could be the combined starting load causing your trip. Try having the AC fan on all the time.
     
  8. RCB

    Thread Starter New Member

    Jan 21, 2013
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    Bill, great thought about keeping the fan on to reduce start up amps, and I was hoping the solution to my problem. With the fan running continuously, the AC is on the verge of starting up in eco mode (and sometimes does), but you can hear the strain on the engine and the AC compressor. Not good.

    In short, I have resigned myself to run the AC with the eco switch off.

    Richard
     
  9. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
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    Sorry to hear that it didn't work reliably. We bought our generator when we had a week long power outage due to an ice storm. Ran a heavy duty extension cord inside and branched off to run the refrigerator, freezer, furnace (gas) and TV. We kept it on eco mode and had no problem. Filled the tank before leaving for work and again when I got home. Other than shutdown for filling, it ran around the clock for a full week.
     
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