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[Solved] SOLVED Vbus Overrange Issue!

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Posts: 11
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(@coolrunnings)
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Joined: 2 months ago

I previously found that certain loads cause the 18kPV to fault out with a "Vbus Over Range" error, despite being completely off grid and not being connected to any PV. Specifically, my UPS was causing it, but I learned that certain other loads would do it as well. Anything with a low power factor turns out. Hair dryers that use a half wave rectifier for the low setting, a coffee maker with digital controls, and a laser printer are also items that caused the problem. It wasn't just that particular inverter, as those same loads caused a second 18 kPV to do the same. It wasn't a wiri g issue as I read some people suggesting in similar posts. I connected the loads directly to the inverter to test with the same results. 

So somewhere along the way I plugged in a watt-hour meter that showed me the power factor. And all of the various loads that caused the fault had a terrible PF. So it dawned on me to go down that rabbit hole. Long story short, I experimented with some capacitors across the inverter output to correct the PF... And it WORKS! I found that 160 uF of capacitance works for the UPS or hair dryer, but not both. 240 uF takes whatever I throw at it now. Two hair dryers, the coffee maker, the UPS, the laser printer. All of it works now.

Of course, the capacitors have about 21 amps flowing across them,  but it is all reactive current, so the inverter doesn't even register it. It takes almost no power from the battery to keep that 21 amps bouncing in and out of the caps, so as far as I'm concerned it is a win.

 

Maybe this will help someone else. I know there was one guy that had a problem with a laser printer here as well. Maybe EG4 can implement a fix. Maybe they can send me a free battery or two for solving this problem😁

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Posts: 4
(@brokenpointjoe)
New Member
Joined: 3 months ago

Thanks CoolRunnings  I agree EG4 owes you a gift. Now that you have cleared the path, I wonder if EG4 will follow it.  

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Posts: 37
(@dannybeardsley)
Trusted Member
Joined: 2 months ago

Wow. Can you point to some specific capacitors that can handle that?

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1 Reply
(@coolrunnings)
Joined: 2 months ago

Active Member
Posts: 11

@dannybeardsley I used standard 370 volt motor run capacitors available from any motor shop or appliance parts dealer. Or online from Grainger, etc.

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Posts: 22
(@wardo5757)
Eminent Member
Joined: 1 month ago

Just a thought-  If this fixed the problem, do you think you may have a bad cap or caps in your inverter? If this issue was caused by these common appliances there would be many many others complaining also. 

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(@coolrunnings)
Joined: 2 months ago

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Posts: 11

@wardo5757 It happened on two separate inverters. Some people have mentioned it. One guy had a laser printer that did it. People on the Diy solar forum have talked a little about certain loads causing similar trouble.

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(@jsaginaw)
New Member
Joined: 1 week ago

@CoolRunnings very neat find - I found this thread as I was wondering if anyone had added bus capacitance to the output of the 18K, but to solve a different issue of GFCI/AFCI combo breakers failing. My breakers are happy running off grid power but fail "self test" when running off the inverter.

Do you have any idea what your sine wave looks like after adding the capacitors? I imagine it must be better than before as though it is pure-sine it's still digital recreation. 

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(@coolrunnings)
Joined: 2 months ago

Active Member
Posts: 11

@jsaginaw I used an oscilloscope when 8 first started trying to solve this issue. The inverter outputs a sine wave, but I didn't study it very close to the edges. I noticed it went lopsided when one of the bad PF loads would kick on, but I didn't look hard at the initial sine wave.

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