Will a stabilizer help start a compressor? (high starting current requirement)

Aluminiumni
Aluminiumni Registered Users Posts: 5 ✭
in Advanced Solar Electric Technical Forum #1
Hello,

I couldn't find (clear) information regarding this relatively simple question on the net.

We have a Yamaha generator with an economy mode (load dependent rpm) -- interested to know if it could actually run an Air Conditioner with its compressor switching on and off because of temperature settings (certain types of stabilizers or other equipment might help bypass the high initial starting current requirement).

* Economy mode max power/AC constant power ~ 9/7
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Will a stabilizer help start a compressor? (high starting current requirement)

    Welcome to the forum.

    Simple answer: no.

    More complex answer: if you're talking about a Voltage stabilizer on the output of a Yamaha inverter-generator it won't make any difference because Voltage isn't the problem here, current is. Or rather the inability of the generator to react fast enough to a sudden demand for a great deal more current.

    If you could tell us specifically which generator and what A/C unit you have someone could probably come up with a practical solution. Although it would likely be to replace the A/C with one that doesn't demand so much current.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #3
    Re: Will a stabilizer help start a compressor? (high starting current requirement)

    Cariboocoot is quite correct. There are no magic circuits that can make up for power that isn't being produced in the first place. However, that said, we all wish there were. :D
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  • Aluminiumni
    Aluminiumni Registered Users Posts: 5 ✭
    #4
    Re: Will a stabilizer help start a compressor? (high starting current requirement)

    Thanks for the quick reply Cariboocoot, :)

    I was thinking maybe stabilizers had inductive storage and it might match the AC motor's requirement.

    So its an issue of having 0 momentum in the beginning? He he, got to recall a fond memory as a child playing with a DC adapter and a motor. The load indicating light would even totally dim in the initial phase of spinning if I really increased the wingspan (and voltage!).

    Um, one possible solution I had in mind was to have a big UPS capable of handling the AC. We do want to get at least some solar.

    I'm thinking about maybe a (custom?) charging off mode (or additional invertor + ATS component dedicated for the AC?):

    The generator might run the AC, drop down rpm when the compressor turns off. When the compressor would turn back on, the UPS might switch and handle the AC for a while and switch back to the generator.

    Maybe a circuit could aid the process:

    on sensing load being > AC constant load
    > disconnect generator from UPS

    UPS switches, circuit reconnects after say 20 ms

    assuming the UPS only switches back after sensing stable power for 3 s:

    over 3 seconds increasing load (buffering function) is placed on the generator

    load ~ equal to constant AC load, and on sensing load on the UPS-generator connection cable, buffer and AC loads switched

    Hey guess what, the light is about to go for an hour (now gone) -- the UPS' state is cool, but I wanna take (it as a an excuse for) a break 'n thinking about stuff. :)
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Will a stabilizer help start a compressor? (high starting current requirement)

    UPS = TSW inverter + batteries. Some of them are not TSW which won't help the A/C any. What's more, in the A/C tests we've had reported on the board here the initial demand is quite high followed by much lower running current. So to have a unit that would take that initial burst is going to cost some money. And then all it's going to do is handle the surge, so is that money well spent?

    At this point the question needs to be asked: why are you trying to run an A/C from a generator? If we know the circumstances there may be a more practical solution (such as going whole-hog on the batteries & inverter to run everything then just firing up the gen to recharge the batteries as needed).
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #6
    Re: Will a stabilizer help start a compressor? (high starting current requirement)
    Aluminiumni wrote: »
    Hello,

    I couldn't find (clear) information regarding this relatively simple question on the net.

    We have a Yamaha generator with an economy mode (load dependent rpm) -- interested to know if it could actually run an Air Conditioner with its compressor switching on and off because of temperature settings (certain types of stabilizers or other equipment might help bypass the high initial starting current requirement).

    * Economy mode max power/AC constant power ~ 9/7
    To join the chorus:

    No. But let's look at a couple of things you could possibly do, assuming that you have a particular A/C you want to use rather than this being a very general question:

    1. Turn off economizer mode when you are running the A/C Probably the least expensive short term solution, but it does have its costs in wear and fuel consumption.
    Basically a generator w/o economizer turned on both has the initial voltage the motor windings want and can rob short term from motor/generator inertia to deliver surge power while the engine throttles up.
    Am I correct that without economizer you can start the A/C? If not, then you just have too small a generator.
    2. Get a soft start circuit for the motor. This could be more difficult for the built-in compressor in an existing A/C than for a standalone motor. Newer A/C units, particularly mini-splits are available with an inverter driven, frequency controlled compressor motor. That allows the compressor to soft start and also to run at reduced output instead of cycling on and off.
    3. Get really tricky (ala Rube Goldberg, but slightly more practical) as follows:
    a. connect the thermostat so that instead of directly driving the motor (or motor controller in the A/C) it drives a relay.
    b. that relay will drive a second relay which is a minimum of two pole time-delay relay.
    c. the immediate result will be that the normally closed (NC) contact of that relay will drive a resistive load just large enough to cause the Yamaha to come out of econcomizer and go to full throttle.
    d. the delayed function of the second relay will be to disconnect the resistive load and using the other pole(s) connect the compressor motor or the compressor motor control circuit.

    If you do not have an A/C or the existing A/C is old enough to be inefficient, spend the money on a new A/C which is compatible with the generator and save fuel costs at the same time.
    SMA SB 3000, old BP panels.
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  • Aluminiumni
    Aluminiumni Registered Users Posts: 5 ✭
    #7
    Re: Will a stabilizer help start a compressor? (high starting current requirement)
    Cariboocoot wrote: »
    At this point the question needs to be asked: why are you trying to run an A/C from a generator? If we know the circumstances there may be a more practical solution (such as going whole-hog on the batteries & inverter to run everything then just firing up the gen to recharge the batteries as needed).

    Yeah, initially I used to think it would be awesome to have batteries act as a buffer for a constant rpm generator and wildly varying load, but the cost structure, at least for non-tubular ones left a bad taste in my mouth:

    roughly $130 for 12 V 200 Ah hybrid flooded in Pakistan http://priceweb.pakistanpoint.com/cars-bikes/batteries-dry-wet/exide-18amp-200ah-battery-np-210.html (not sure if the price is current, same picture shown for similar batteries)

    ----> possibly 1000, 50% DOD cycles ----> very roughly 1000 1kWh cycles ----> roughly, possibly 1000 * $0.1 = only $100 worth of energy savings

    It looked like a generator would necessarily have to be part of the picture given cloudy days and unexpected (something like twice a month) additional load-shedding (possibly) at night (regular: 8-14 hours or so daily, 3-4 hours additional, but can even be 8 hours with a significant utility failure).

    Since we already planed to be making use of 3 portable (dual hose) 13500 Btu ACs with an okay EER (9.5), it seemed that a solution might be to get solar to cover powering all three and "store the cooling" for the night (Pakistan doesn't have residential feed-in tariff right now, though it might soon). Still, I guess we got the generator, wanting to look at solar later. *further edit: yeah inetdog, looks like economy mode off starting would be fine (5.5 kW rated output).

    I was actually wondering about a custom UPS project (kinda dreaming as I only used to have a very very basic hobby). I feel you guys must know of circuits that might make use of 10+ batteries to bypass having to use a transformer; for example:

    a 12 V battery, 2*12 V, 4*12 V, 8*12 V banks, and another 12 V battery for varying 0-12 V to match a sinusoidal waveform:

    0000 only 0-12 V
    0001 0-12 V in series with 12 V
    0010 0-12 V in series with 24 V
    0011 0-12 V in series with 12 V and 24 V
    ,
    ,
    .

    Maybe relays could take the batteries out for individual, final topping up charging (initial phase could be done directly with rough waveform matching and maybe boosting 120 V mains). They could also circulate the battery positions in the banks (for the next outage, each time switching to mains).

    inetdog, I'll try to look at your post again later.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #8
    Re: Will a stabilizer help start a compressor? (high starting current requirement)

    Many "Mini-Split" heat pump / AC units have inverter compressors which have no surge on start-up, and are FAR more efficient than your AC units. These inverter compressors start very slow and easy, then gradually ramp up to whatever speed is needed to do the job, using only the power required to do the job. You will pay more for them initially, but the savings in the area of your power supply will definitely outweigh that cost, and the satisfaction you receive will be far ahead of any window shaker AC. And QUIET! They are VERY quiet!
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,022 ✭✭✭✭
    #9
    Re: Will a stabilizer help start a compressor? (high starting current requirement)

    I agree with Wayne...very quiet. When in a/c mode you have to get to within 2 feet of the outside unit to hear the fan running, ear almost on the housing to hear that the compressor is running. Inside air handler unit can be below whisper threshold if on low (is it running?), on high still below conversation voice level. Mitsubishi 12000btu minisplit.

    Ralph
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