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  • Inverter Generator Overload - Symptoms?

    Well, El Nino may have been a bust, but I did my best to prepare. Finally after being snowed in, there was a planned outage for maintenance and I dusted off my Generac 2000 inverter generator (http://www.amazon.com/Generac-6719-P...rter+generator) and plugged it into my manual transfer switch.

    Took a few pulls to get it started, but all went well. Power was scheduled to be out from 8AM to 6PM. At 3:30 my generator stopped. I figured it was out of gas, the tank only holding 0.82 gallons. I re-filled and started it back up. It started on the first pull, but the overload indicator was red and it did not put out any power even with no load. I had a boat anchor. About 1/2 hour later I tried again. this time it started with no red indicator. It worked until power was restored at 9:15 ... yes they were late.

    I felt very good about what was powered, but have this nagging feeling that I need a bigger generator. Does anyone know why the overload light would be on with no load? I called tech support and all they could say is if that light was on, it was either overloaded or overheated. I don't feel good about this being a piece of emergency equipment.

    I had the following powered most of the time.

    1) TV/ Computer on UPS - about 100w
    2) Modem and Verizon Extender on another UPS - about 25w.
    3) Led lights on and off, probably no more than 4 at a time - about 100w.

    The panel on my transfer switch did read about 250w most of the time.

    I also powered successfully:

    1) 700w microwave for 5 minutes or so.
    2) Macerator toilet at about 750w for a 30 second flush.
    3) Hand mixer
    4) None of these all at the same time.


    But the following I think were a potential problem:

    1) Small dorm refrigerator.
    2) Larger Frigidaire in basement - label is 6 amps

    Every once an a while the generator would rev up and it appeared that the temps were maintaining in freezer compartment and refrigerator compartments for both.

    I am suspecting that the first time the generator stopped was due to overload. Does anyone know how a small inverter generator handles this sort of overload?

    I am considering taking this back to Costco and getting one rated at 3000w. I may even spring for the Honda.

    Advice, suggestions and comments on what may have happened and how inverter generators protect against overload?




    Last edited by lkruper; 03-10-2016, 09:59 AM.

  • #2
    It is possible that the generator went into overload during the start up of that big frig in the basement. It being out (or maybe close to out) of fuel could have been a coincident.

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    • #3
      I had the same thought as well after I reflected on what happened. Still it is supposed to get 4.7 hours on 0.82 gallons and I got a bit over that. Do you think that the Honda 3000 at about $1999.00 is worth the money? From what I can tell it is about a $800 premium over a lesser known brand.

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      • #4
        I have no first hand experience with the 3000 watt unit but I have been up close and personal with the e2000i. First off it was so quite I didn't know it was even running. Second it provided very clean power while running my friends satellite receiver and tv. While I am sure part of that premium cost is in the name IMO the rest is in the quality.

        Another quality unit is made by Yamaha, but that too is in the same price range as the Honda units.

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        • #5
          Possibly one thing that turns on the Overload indicator is an internal thermal trip in the inverter circuitry which is more sensitive than the thermal trip of any associated breaker, If that is the case it might not reset until the innards of the inverter have cooled off.
          If it uses a Klixon or other similar bimetal there will be some controlled hysteresis and the temperature would have to come down well below the trip temperature before the overtemp switch would reset.
          SunnyBoy 3000 US, 18 BP Solar 175B panels.

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          • #6
            I asked why the red light came on and the tech support guy said overload or temperature. However, the ambient temperature was in the 50-60s. Are you suggesting that an overload condition could raise the temperature of components in the inverter?

            The other thing that makes me re-think this generator is that when I told him how I was using it, he said it was not designed to power a residence, but for recreational use. Then I told him that I was averaging 250-500w unless I used an appliance and he then backed off on that criticism, however it makes me wonder if this is really not suitable for emergency use.

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            • #7
              Originally posted by lkruper View Post
              I asked why the red light came on and the tech support guy said overload or temperature. However, the ambient temperature was in the 50-60s. Are you suggesting that an overload condition could raise the temperature of components in the inverter?
              Yup, that is one of the damage-causing mechanisms of an overload.
              There will be a small effect that the amount of power that the inverter can deliver before overload indication will depend on ambient temp and ventilation around the generator.
              Also note that that particular overload will be based on current delivered, not watts delivered. So a lightly loaded electric motor with a power consumption of 250W but an inductive power factor of .5 will load the inverter just as much as a 500W load with a PF of 1.0. The engine will see a lower load though.


              SunnyBoy 3000 US, 18 BP Solar 175B panels.

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              • #8
                Thanks, and what about the load of a refrigerator compressor? I called Frigidaire a few times and talked to various people and even after they escalated they would not tell me what the draw was at startup.

                Comment


                • #9
                  if it did run out of fuel it may have tripped while surging as it was running out of fuel. The engine rpm will go from almost zero rpm to 3000 a few times before it stops.

                  The stated" Not meant to run a house" may relate to expected life.

                  Small chainsaws years ago had an expected life of 20hrs. For most this will mean years as they were designed to trim a tree now and then. When used to cut fire wood they would be worn out in a year.

                  Your generator is designed to go camping a couple of times a year, by saying you were running a house he may have been thinking 24/7 365.

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                  • #10
                    Thanks, I was wondering what happened if it ran out of gas. I did make a point to tell him that I bought it in the summer and ran it once and this was only the second time I had used it. It sounded like he was concerned about the load. However this is a cabin and only 500 sq ft plus I am not powering the 220 stove or hot water heater.

                    If this is what happens when it runs out of gas, it is problematic as there is no way to see how much gas is in the tank. There is a rubber button for priming that appears to show gas, and it did have some gas showing in this "window" when it stopped.

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                    • #11
                      petrol stationary engines dont generally just die when they run out of fuel, as they start to starve they surge and the surges get bigger until they stop. Obviously potential for voltage surge. I dont know how inverter units. Normal? generators dont care they just surge whatever they are running.

                      if you need longer run time per tank fit an external tank to whatever size you want.

                      Comment


                      • #12
                        If you had other loads running, and any of the fridges started up, or if one fridge was running, and the other started, I would expect that to trip the protection circuit. You may also have Power Factor issues too, with more than one motor (fridge compressor) running.
                        Another not unheard of thing, is some of the insulation blanket coming loose and blocking air flow internally. Normally, a light load should not build up much heat, but if cooling was compromised........
                        Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                        || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                        || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                        solar: http://tinyurl.com/LMR-Solar
                        gen: http://tinyurl.com/LMR-Lister

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                        • #13
                          I believe there is a good chance that I did overload the generator. Honda has a page (http://powerequipment.honda.com/gene...wer-management) promoting their transfer switch that has power management and switches off loads so they don't power at the same time. Their figure for the refrigerator, when factored into my situation, could easily cause me to exceed 2200w, and that probably happened during the day I used the generator.

                          They say one can use a much smaller generator if one manually turns off appliances to run others. Of course that is a big pain, and so their product will solve that problem. But it got me thinking, what if I put timers on my two refrigerators so that they never powered at the same time?

                          I have one of these switches (http://www.amazon.com/gp/product/B00...rch_detailpage) and it seems to work well so far to allow me to remotely cycle power. The specs are: Ratings: 125-Volt / 60-Hertz, 1000-Watt Tungsten, 15-Amp Resistive, 1/2-Horsepower. At first glance this appears to be hefty enough to handle a refrigerator that has it's factory label set at 6 Amps. But would this handle a surge of 1600w? If not, is there a better type of switch that could handle this?

                          Also, If I were to cycle a refrigerator on an hourly basis, would this damage the compressor? This would likely not happen very often, only when there are power outages.

                          Comment


                          • #14
                            Originally posted by lkruper View Post
                            I believe there is a good chance that I did overload the generator. Honda has a page (http://powerequipment.honda.com/gene...wer-management) promoting their transfer switch that has power management and switches off loads so they don't power at the same time. Their figure for the refrigerator, when factored into my situation, could easily cause me to exceed 2200w, and that probably happened during the day I used the generator.

                            They say one can use a much smaller generator if one manually turns off appliances to run others. Of course that is a big pain, and so their product will solve that problem. But it got me thinking, what if I put timers on my two refrigerators so that they never powered at the same time?

                            I have one of these switches (http://www.amazon.com/gp/product/B00...rch_detailpage) and it seems to work well so far to allow me to remotely cycle power. The specs are: Ratings: 125-Volt / 60-Hertz, 1000-Watt Tungsten, 15-Amp Resistive, 1/2-Horsepower. At first glance this appears to be hefty enough to handle a refrigerator that has it's factory label set at 6 Amps. But would this handle a surge of 1600w? If not, is there a better type of switch that could handle this?

                            Also, If I were to cycle a refrigerator on an hourly basis, would this damage the compressor? This would likely not happen very often, only when there are power outages.
                            Note the three specifications on the switch:
                            1000-Watt Tungsten
                            15-A (1800W) resistive
                            1/2 horsepower (about 500 VA)

                            There is a reason for that.
                            A resistive load has no surge and no inductive kick when turned off. So 15A total current.
                            A Tungsten (incandescent light) load has a turn on surge while the filament is cold, so only about 8A
                            A motor has a large starting surge but more important an inductive component to its current so it tends to arc more when the switch is opened, so only about 4A.

                            A refrigerator with a label Full Load Amps for the compressor of 6A will correspond to more than 1/2 HP. You may not have any problems, or the life of the switch may be greatly reduced. Depends on how conservative the design and rating was.

                            Cycling a refrigerator compressor every hour should not be much different from its normal cycle. The one thing you need to avoid (and it should not be a problem for you) is turning the power off and then on again in less than a few minutes when the compressor was running. The compressor will not start under the load of refrigerant pressure and so the motor will stall and overheat until the overload cuts it off. It will restart successfully after cooling for a few minutes and letting the pressure bleed down. That will reduce the motor life if done too many times.
                            SunnyBoy 3000 US, 18 BP Solar 175B panels.

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                            • #15
                              The only problem with switching power to a fridge, is the defrost cycle timer. An old school clockwork motor timer inside the fridge works fine. But newer fridges have electronic timers and power cycles "can" confuse the defrost cycle. You will have to watch and observe carefully.
                              Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                              || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                              || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                              solar: http://tinyurl.com/LMR-Solar
                              gen: http://tinyurl.com/LMR-Lister

                              Comment

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