[RE-wrenches] generator tripping GFCI

Sun Dec 20 09:08:33 EST 2020

Thanks all for the comments and ideas.

To recap, the reason I don’t think its in the wiring or loads is that everything is normal no tripping if inverter bypass or inverters running normally.  
This says to me that it can’t be a loose neutral, or wires or some odd loads etc.  
And no additional loads when the generator is on.  

I don’t think its the neutral/ground dual bond issue as I would think that would cause the tripping but its not. I will check again.  

Which leads me into the inverter/generator interface.  Yes they are older inverters but working normally I don’t think there are issues inside the inverters or the client would see at least periodic tripping of things, but none occur.

I have seen generators not being able to handle the poor PF from the inverter setting up similar kinds of things.  Certain appliances not operating normally, LED lights having odd behaviors etc.  Again, generator or inverter is all fine, but while battery charging these things are happening.  

The older VFX do not have the Radian/FXR special generator waveform smoothing setting.  

Which leads me to the following next steps.

1. check again for ground/neutral bonds at the generator. 

2. have them use another good quality generator as a test.

Any other tests folks would have me run?

thanks

jay

> On Dec 19, 2020, at 8:37 PM, Chris Worcester <chris at solarwindworks.com> wrote:
> 
> It might be worth checking the brushes if it is an older unit. 
> 
> 
> 
> Chris Worcester 
> chris at solarwindworks.com
> 530-448-9692
> 
> Sent from my Samsung Galaxy s9.
> 
> 
> -------- Original message --------
> From: William Miller <william at millersolar.com>
> Date: 12/19/20 6:30 PM (GMT-08:00)
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
> Subject: Re: [RE-wrenches] generator tripping GFCI
> 
> Friends:
> 
> I have seen THD on the voltage waveform trip GFIs and AFCIs. The case where this happened was during gen run periods. AC to DC converters can be brutal in regards to generating distortion and sending it to loads. 
> 
> I am out in the shop away from the manuals, but check if these FX inverters can be programmed for Support mode on the gen input. This may knock THD back to acceptable levels, if indeed this is the cause. 
> 
> Best of luck. 
> 
> William Miller
> www.millersolar.com
> 
>> On Dec 19, 2020, at 5:33 PM, Darryl Thayer <darylsolar1 at gmail.com> wrote:
>> 
>> 
>> The way a GFCI operates is by comparing the line current and the neutral current inside the device.  If some of the neutral current is returning through a ground circuit instead of the neutral the imbalance will trip the device.  The generator neutral and the inverter neutral must have a common neutral-ground bond and only one!  
>> Your presentation indicates operational differences, multiple bonding points (two or more) can cause a neutral ground imbalance when load, source changes occur.  The load-source changes can affect the tripping result.    
>> 
>> On Sat, Dec 19, 2020 at 5:23 PM jay <jay.peltz at gmail.com <mailto:jay.peltz at gmail.com>> wrote:
>> HI All,
>> 
>> I have a client with a older Kohler 8-10kw generator, VFX 3648 stacked inverters, newer rolls batteries. its been installed and operating normally for 10+ years.
>> 
>> Customer had to upgrade the house for code, which involved installing GFCI outlets and GFCI breakers.  
>> 
>> Since then the  GFI outlets trip every time the generator starts but only after 3-30 minutes.   They work normally on the inverters. And if you do a bypass/generator direct the GFI outlets don’t trip.
>> 
>> The GFI breakers trip when the generator is about to turn off, not during warm down but say 30 minutes before it will turn off.  So charging current is at the lowest. And again they all work normally on the inverters and all the rest of the charge cycle.
>> 
>> 
>> Voltage is a bit high, around 254v-259v from the generator but it is the whole time and seems to stable voltage. But if the voltage was the issue the outlets would keep tripping.  If it was too high for the breakers, why at the end and not the beginning?
>> 
>> I’m thinking its possibly a control board in the generator that’s not working well.  Can’t keep up with the PF for the inverters, etc.  
>> 
>> Buts its a new issue I’ve not run across.
>> 
>> Any ideas?
>> 
>> thanks
>> 
>> jay
>> 
>> peltz power
>> 
>> 
>> 
>> 
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