so, I bought a KVAR...you know the power saver

I bought a kvar power saver....despite the bad rap it gets
reason I bought it:

let me tell you what I have and why I thought this might work. XW4548 ( first gen ) ....duramax 3500 watt generator.....completely off grid
system works fine through the day, runs everything I need.....at night when the batteries start going down, the AGS kicks the generator on like it should. once it has qualified the AC it starts its charging cycle...no problems...gen support is set at 10 amps...gen support plus is enabled

once the refrigerator comes on, the lights dim and sometimes the generator will stop charging....not always
   once it starts it's charge cycle again, no problems as the refrigerator is already running

so back to why I bought I was thinking that putting the kvar between the generator and the AC2 inwould solve the surge problem.....it didnt, ...it trips the generator braker after about 40 seconds.....not sure why

so I put it on the inverter out to load side....that made the inverter stop inverting for half a second every 4-5 minutes...I think because power isnt supposed to be imported on that side, just exported, which I figure the kvar was shorting and supplying a lot of juice

I just wanted to be sure what everyone told me was right......well, yes and no
I was told it wouldnt help the surge....yes...but that is all I was told....no one said it would cause interruption to the power

so...back to the search to fix this problem of the lights dimming while the generator is running

think I will try a hard start or a soft start capacitor on the refrigerator itself...that shouldnt cause a problem

what are your thoughts on the matter

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,644 admin
    Installing the KVAR capacitor should be on your switched loads (i.e., on the compressor motor side of the pressure switch, and not directly on the "raw" ac mains of your system).

    Placing a capacitor on the AC live output will simply draw maximum current the capacitor can draw (+90 degree lead on the current).

    The idea is that you place a (matching run capacitor) in parallel with the inductive load. Basically, the math is you can "add" the -90 current of the induction motor with the +90 current lead of the "matching capacitor value" and they zero out (and the only in-phase current is present). And should bring the Power Factor (Cosine of the voltage/current phase angle) to near 1.0 (actually the "perfect" PF is 0.95 maximum for various reasons--One of which is a too big of capacitor can work with the induction motor to turn the motor into a generator and create excessively voltage while the motor slows down, after AC power has been cut).

    If you put a Capacitor (or Inductor) on the output of your AC inverter (or AC mains)... You just draw a bunch of current at 90 degrees (+/- relative to the voltage).

    Because Cosine 90d = 0.0 (power=V*U*Cosine phase angle V vs I) --- That means that the Capacitor (or inductor) do not draw any "power". However, the inverter (or ac mains) has to supply a lot of out of phase current which does create heat (resistive loses, magnitization losses in transformer/alternator pole pieces, etc.). And cause a circuit breaker to trip or the inverter to self protect/fail (i.e., the difference between a smaller or larger value of capacitor).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • t00lst00ls Solar Expert Posts: 218 ✭✭✭
    BB. said:
    That means that the Capacitor (or inductor) do not draw any "power". However, the inverter (or ac mains) has to supply a lot of out of phase current which does create heat (resistive loses, magnitization losses in transformer/alternator pole pieces, etc.). And cause a circuit breaker to trip or the inverter to self protect/fail (i.e., the difference between a smaller or larger value of capacitor).

    -Bill
    yup...sounded exactly like what was happening......I figured it was self protecting, using the stored power then coming back on...just takes a fraction of a second for the XW to do that

    so if I put this thing on the side of the switch that doesnt see power....once the fridge kicks on....I shouldnt have a problem

    maybe I just get a hard start capacitor like the RV ers do and give this thing to someone that is on grid


    thanks bill...I know hardly anything about capacitors

  • mike95490mike95490 Solar Expert Posts: 8,434 ✭✭✭✭✭
    What's happening is that new generators, have cheap windings and poor power factor performance.  I can barely run my pump off a modern subaru-hatz 3Kw genset.  Running it off my antique 3Kw genset, I can pump, charge batteries and run the house.  When the genset runs out of power factor, the pump controller kicks the pump off to prevent damage to the pump.
    Powerfab top of pole PV mount | 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 ,

  • t00lst00ls Solar Expert Posts: 218 ✭✭✭
    I agree with poor windings....you get what you pay for...this generator cost me $300 new if that tell you anything

    anyways...back to the subject....I actually spoke with the inventor/maker of the KVAR power saver...we both agreed that the kvar cannot be used on the mains in an offgrid situation

    so...I did what I shouldve done in the first place...bought a supco 3 in 1 hard start capacitor.....something wonderful happened

    I am running about everything I normally run.....the generator has usually kicked on by 10 pm.....it hasnt

    I believe that the refrigerator is using less power overall.........gonna wait another day before I claim it as truth and also....I have yet to see if the lights dim...because the generator hasnt kicked on , also havent looked at the amp use yet

    so if this is correct...I'm gonna be installing these things on other peoples refrigerators and possibly an spp6 on their AC cooling units
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