Automatic Transfer Switch issues (?)

thorsnessthorsness Solar Expert Posts: 52 ✭✭✭
At my remote cabin, we have a great system: two 12 volt sealed AGM batteries, one solar cell, breaker panel, a controller, an automatic transfer switch and a 1000W inverter. The system is designed so in the dead of winter, I can power the system with our EU2000W Honda, leave the inverter on, including the battery charger, then say, just before bedtime, unplug the generator and have the system automatically switch to battery-inverter power with just a barely perceptible flicker when I shut down the generator. This used to work fine. Now, if i have maybe four lights on (about 100W of total draw with the CF bulbs), when I shut down the generator, the lights all rapidly flicker, the red "fault" light on the inverter comes on and there is a rapid "ticking" sound (like arching, but not loud, no sparks, smoke, etc.) from the breaker panel (this ticking seems to be coming from the side of the box where we have two 20 amp breakers). I cure it by shutting off the lights and shutting off the inverter, then switching the inverter on again, then the lights one by one. Sometimes, if I get all but one light off, the flickering stops and I can turn the rest of the lights back on with no problems.
Two events preceeding this phenomena come to mind: the mounting screws that hold the switch box to the underside of the stairway got wacked by a hammer (a long story but this was the first time the "flickering" occurred. No generator shutoff. We were already on inverter power), and the second was my young daughter ran our Orek vacum without the generator on, i.e. just on the two 12 volt batteries (when i came in I could smell the vacum motor begining to cook).
I have cycled the breakers on and off a number of times. I have looked inside the transfer switch and nothing looks burned up. If I shut down all but one light and pull the plug out of the generator, the switch seems to work as before. And the ticking in the breaker panel is replaced by a very quiet "buzz."
Ideas anyone? Thanks very much.



  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: Automatic Transfer Switch issues (?)

    What transfer switch are you using?

    It sounds like maybe it is a low voltage disconnect issue. Does it happen if you try it with only one light on? What fault light shows up? What inverter? Sine wave or modified sine wave?

    Have you taken the cover off all the panels and made sure that all the connections are tight?

  • BB.BB. Super Moderators, Administrators Posts: 28,176 admin
    Re: Automatic Transfer Switch issues (?)

    I am guessing you have a 1,000 watt MSW inverter (modified square/sine wave inverter).

    Don't think the automatic transfer switch is bad (is it electronic or just a relay?). If the transfer switch is a relay, sometimes you can check the leads and contact points and see how they look (and possibly even take a point file and clean the contacts).

    My guess is that either one of the CFL lamps is going bad (flickering) or the Inverter is getting towards it last legs.

    Try unscrewing one lamp at a time and see if the flickering will go away--repeat until you have check all your lamps.

    It is possible that one of the breakers is have a problem (not likely) and you can try jumping the lights directly to the inverter around the transfer switch/breaker box... Not knowing your setup, I would guess the 20 amp breakers (if they are on the 120 VAC branch from the inverter to the lights) are not really needed. The inverter will not be able to output that much energy.

    Another thing to look for is for the insulation on one of your 120 VAC branch circuit wires going bad and occasionally making a bit of contact to earth/safety/green wire ground (MSW inverters generally do not like a grounded neutral wire in AC wiring if the DC input terminal is grounded too).

    Lastly, unless you have need for that large of inverter (1,000 watts), you might want to look at the Morning Star 300 watts (600 watt peak for 10 minutes) True Sine Wave inverter. A single solar panel does not output that much power and the smaller 300 watt TSW inverter should be a bit more efficient. The MS TSW inverter also has very low standby current (you can probably leave it running at night if somebody wants to turn on a light).

    The low buzzing noise may be just the normal operation of the MSW inverter (wire vibrating, something in a breaker, piece of sheetmetal somewhere, etc.)--they can be more noisy than a TSW inverter.

    The last weird thing I can think of--I have an outdoor motion detector light with a pair of 13 watt CFL flood lights. And if the head is too close to the white wall/lights, the CFL's will blink on and off rapidly. And, in my home (utility power), it even caused my CFL's in the house to flicker too. Pointed the motion detector farther away from the lights/wall and everything was fine.


    PS: Tony has a good idea too... Use a good volt meter and measure the voltage at the battery and at the inverter--there should only be a few 0.1 volts difference... If you see 2 volts or larger, you probably have a loose connection or bad wire. You can put the voltmeter on 2 volt scale and measure the voltage drop across each contact/wire and see if there is a large voltage drop somewhere...

    And, what is the battery voltage (inverter input voltage)? If you are below 12 or 11 volts, perhaps your batteries are starting to fail (or you are having problems charging).
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • RCinFLARCinFLA Solar Expert Posts: 1,280 ✭✭✭
    Re: Automatic Transfer Switch issues (?)

    CFL change over time as the bulb ages. Some are very picky about their operating voltage and waveform. I assume your inverter is modified sinewave which some CFL do not like.

    Another variable is winter temperature. Cold temp may also be causing your problem with the CFL's.

    Try incandesent bulf to see if problem goes away. New CFL may solve issue. There are some real junk CFL's out there. Philips seems to be best.
  • thorsnessthorsness Solar Expert Posts: 52 ✭✭✭
    Re: Automatic Transfer Switch issues (?)

    Thanks RC. I'll give that a try.

  • thorsnessthorsness Solar Expert Posts: 52 ✭✭✭
    Re: Automatic Transfer Switch issues (?)

    Thanks Tony and Bill and RC,

    I did tighten the connections in the breaker box but i will look at more of them this weekend. Perhaps when the transfer switch got whacked, something loosened a bit.
    It does NOT do this when I leave only one light on and sometimes stops when i start turning lights off.
    Modified Sine wave, 1000W Xantrex inverter. I have a smaller one (300W) already on line. Perhaps I'll try that and see what happens. You guys are correct, with all of my inside and outside lights on, my total demand is 180W. With the kids DVD player going to, it can't be much over 200W so the inverter i have is overkill it would seem.
    I will try an incandescent bulb and see.
    Thanks again for your generous advice. Snowing here today. Temps a balmy 20*f which beats heck out of -20*!


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