GFI simply looks at the current going out on the hot wire and the current coming back on the neutral. If the currents are not identical, the little transformer they pass through creates an output voltage that trips the unit. The transformer is wired such that the two currents cancel each other. So when they are the same, they totally and perfectly cancel. If more current is on the hot than the neutral (or the unlikely situation where there is more on neutral than hot) it trips..
If it is tripping, somewhere current is leaking out of the circuit and returning via earth ground. You can always put an isolation transformer on the output which will stop the tripping and make it safe at the same time. Best to fix the leakage. From: Steve Jones Sent: Wednesday, August 02, 2017 7:29 PM To: [email protected] Subject: Re: [AFMUG] Gfi kicking on portable generator I dont know what actually is happening when a leg is out at a grain elevator that drops to the 60-80, something at the transformer i assume. This is the site i went to swap a ptp500 to a 650 last week and broke their manlift, this site and i have.... history, will probably be where i die, i made it my bitch once and had to climb up in an ice storm with two inches of ice on everything, 6 inch horizontal icicles, still got that up and running wearing khakis and a jacket. Ever since i took its manhood, that place has treated me like its a psycho ex wife. Ill rewire the cutover switch in the morning when the power company gets it fixed up. I do have to have a solution for knucklehead techs though, i think i could have achieved the same thing with a two prong adapter. Just dont want to deal with osha and paperwork if i play croakamope with a tech picking up a generator On Aug 2, 2017 8:14 PM, "George Skorup" <[email protected]> wrote: I see 60-80VAC at grain sites all the time when a phase is out. Pain in the ass. The GFI recept on the gen could just be going bad. Could also be something as simple as noise/surge suppression in your UPS causing it. I wouldn't worry about it. On 8/2/2017 7:12 PM, Steve Jones wrote: Millivolts not amps On Aug 2, 2017 7:08 PM, "Steve Jones" <[email protected]> wrote: Milliamps. But its a brownout/power outage On Aug 2, 2017 6:57 PM, "Jaime Solorza" <[email protected]> wrote: Did it read zero? If not , have that checked...we spent all morning with engineers, electricians and us chasing a weird diesel generator to UPS issue...Fluke meters galore... Jaime Solorza On Aug 2, 2017 5:51 PM, "Steve Jones" <[email protected]> wrote: At a grain elevator right now, brownout type issue, 60v some places none at others. Not our chair, not our problem, except our portable generator gfi trips every time the cutover switch engages. We ended up just bypassing the cutover and only wiring phase and neutral to the generator outlet, leaving ground disconnected. I suppose we could have left everything intact and disconnected ground from the panel, i dont know But what we have now is phase and neutral on generator feeding the outlet up top, the ground is still connected to the service ground up top. We dont have access to a panel its connected at I did measure between the ground at the panel and a known good earth ground. No voltage, i assume that means no hot ground. The concern here is if im missing something and the gfi is kicking because of something i dont have capacity to verify, is running this generator this way a risk of electrocuting somebody who touches the frame? Its ground is not connected in the circuit, same as if id just connected a 2 prong adapter
