So I had a Eaton GFCI that would randomly pop. I swapped it out for a leviton, and now it pops as soon as I run the spindle. Breaker won’t pop, and I am using a GFCI plug as well, and the plug does not pop. (I had 1 from work, and am using it as a switch).
Tested continuity between nuetral and ground at various spots in my wiring, and there is no continuity. I do have a shield on my power cable, which all my grounds are tied into a single point which go straight to the outlet ground.
Not sure what to do. I am suspecting that the shield is draining to the ground, tripping the GFCI. Can’t say for sure. Any ideas?
edit: Moral of the story, GFI’s and VFD’s dont mix.
Is it a water cooled spindle? It’s possible that the water could be providing a path to ground. It doesn’t take much. Also VFDs EMI filters don’t always play well with GFIs. They produce some noise as well as the may have internal capacitors that one side connects to ground to help filter noise. The problem is that GFIs need very little current to go to the ground to trip. If you need to use the GFI then there are some solutions to deal with the problem.
Yes, the waterpump runs on a seperate circuit. It actually runs on a UPS, with the 1F controller. The UPS, and its associated outlet are not GFCI protected, grandfathered.
They produce some noise as well as the may have internal capacitors that one side connects to ground to help filter noise. The problem is that GFIs need very little current to go to the ground to trip. If you need to use the GFI then there are some solutions to deal with the problem
Yea so this is what I am suspecting, a combination between the VFD itself, and the shielded power cable for the spindle, mostly the power cable I think. As I can run the water pump, and have the VFD on, and not trip the GFCI. But the second I hit play on the 1F controller, and the spindle starts to spin now, I don’t get beyond 700 RPMs before she pops.
What are the solutions here? I want to make sure this is safe, and verify this is indeed what is happening. I was thinking of just throwing in a 20A on off switch, and putting that in place of the GFCI outlet, then removing the GFCI plug for a standard plug.
Why was the GFCI there to begin with? If it’s located in a spot where a GFCI is required by code such as a garage or unfinished basement then it should remain or be converted to a single receptacle for the dedicated use of an “appliance” which the VFD would count.
If you are intentionally trying to protect the VFD with a GFI type device look into a GFPE instead, it would permit for a 35mA leakage current which might or might not trip. At the end of the day the VFD is power conversion equipment and isn’t really well suited for connection to a GFI type device.
Remarks for using ground fault interrupter breakers in the main power supply:
Adjustable frequency inverter with integrated CE-filters and shielded (screened) motor cables have a higher leakage current toward earth GND. Especially at the moment of switching ON this can cause an inadvertent trip of ground fault interrupters. Because of the rectifier on the input side of the inverter there is the possibility to stall the switch-off function through small amounts of DC current.
Please observe the following:
Use only short time-invariant and pulse current-sensitive ground fault interrupters with higher trigger current.
Other components should be secured with separate ground fault interrupters.
Ground fault interrupters in the power input wiring of an inverter are not an absolute protection against electric shock.
[…]
For motor leads, ground fault interrupter breakers and electromagnetic contactors, be sure to size these components properly (each must have the capacity for rated current and voltage). Otherwise, there is the danger of fire.
RCD sensitivity is expressed as the rated residual operating current, noted IΔn . Preferred values have been defined by the IEC, thus making it possible to divide RCDs into three groups according to their IΔn value:
high sensitivity (HS): 5** – 10 – 30 mA (for direct-contact or life injury protection),
medium sensitivity (MS): 100 – 300 – 500 – 1000 mA (for fire protection),
low sensitivity (LS): 3 – 10 – 30 A (typically for protection of machine).
The 5 mA sensitivity is typical for GFCI outlets.
Break time (response speed)
There are two groups of devices. G (general use) instantaneous RCDs have no intentional time delay. They must never trip at one-half of the nominal current rating, but must trip within 200 milliseconds for rated current, and within 40 milliseconds at five times rated current. S (selective) or T (time-delayed) RCDs have a short time delay. They are typically used at the origin of an installation for fire protection to discriminate with G devices at the loads, and in circuits containing surge suppressors. They must not trip at one-half of rated current. They provide at least 130 milliseconds delay of tripping at rated current, 60 milliseconds at twice rated, and 50 milliseconds at five times rated. The maximum break time is 500 ms at rated current, 200 ms at twice rated, and 150 ms at five times rated.
Programmable earth fault relays are available to allow co-ordinated installations to minimise outage. For example, a power distribution system might have a 300 mA, 300 ms device at the service entry of a building, feeding several 100 mA S type at each sub-board, and 30 mA G type for each final circuit. In this way, a failure of a device to detect the fault will eventually be cleared by a higher-level device, at the cost of interrupting more circuits.
It is permitted per the NEC, local building official might argue with you - sometimes you’ll win sometimes not… NEC places lots of power in the “authority having jurisdiction” Easiest way to deal with it if you have an issue is to wire it in without a plug. There was a rule that permitted it to be non GFCI if it was not considered “readily accessible” for receptacles over 6’6" from the floor but that has been eliminated in the 2020 NEC.
Yea, I found that in a copy of NEC, looks like it is permitted. Can I throw a 20A switch before the outlet? This way I can pull the GFCI plug out, and just use the switch to kill power for the VFD. While the plug hasn’t popped, I think I want to just eliminate all GFI’s.
Aiph5u
(Aiph5u (not affiliated with Onefinity))
11
Hey Kyle,
I see no reason to do without the protection provided by a GFCI. You could simply
EDIT: I think you have these wall outlets with integrated GFCIs in the U.S.:
Ben Kurtovic, CC BY-SA 4.0, via Wikimedia Commons
I understand this could not be the right outlet to connect a VFD.
Here in Europe we usually have the RCD in the distribution panel/fuse box, or, for VFD, in the VFD’s control cabinet, e.g. such a RCBO which means it’s an integrated RCD and circuit breaker:
I would just swap the outlet out with a standard 20a receptacle. Since it’s a dedicated circuit for the VFD I would get a single receptacle. By code you don’t need a GFCI.
For receptacle(s) feeding appliance(s) located within a dedicated space. A single receptacle supplying power to a single appliance that, in normal use, is not easily moved from one place to another does not require GFCI protection.
I had a GFCI, followed by a single outlet after the GFCI. I removed the GFCI, moved that single outlet over to the GFCI’s spot in the 4" box, then installed a switch, to kill power to the outlet if need be. Seems to be working well. I’ll probably keep an eye on it more then usual for the first couple of weeks, make sure everything is good.
@Aiph5u The solution you posted was either do something that is kind of over my head, OR use a separate GFI.
Yes we have outlets similar to that, I am using a 20A, thats a 15A. I don’t get to select what level of mA will trip it, and the selection is rather limited. Either way, removing a GFCI outlet is up to code, so just removing it is the easiest solution.
In the USA we typically have either simple breakers at the breaker box’s, or GFCI breakers which serve dual function either popping on ground fault OR if the circuit is pulling to much amperage. My panel from 77’ is maxed out and I wouldn’t be able to throw in a GFCI breaker, and it’d likely lead to the same issue so it wouldn’t be optimal.
I couldn’t tell you Eatons or Levitons mA trip rating. I would have assumed it would be similar, still think so, Eaton at Lowes is hot garbage, I’ve installed 3 of them, and 2/3 have failed and multiple electricians seem to be stating the same thing to me. I wouldn’t be surprised if it was just a subpar GFCI outlet not tripping regularly.
As far as GFCI’s and VFD’s not mixing. I been running 3 threads, 2 on reddit, 1 here. This was the conclusion that most are coming too. You might be able to find a way to make it work, but the easiest way is to just drop the GFCI.
GFCI for personnel protection is 6mA maximum leakage current regardless of the amperage rating of the receptacle. For what it’s worth you most likely have a 15 amp cord connected to your VFD.
15 amp plug:
20 amp plug:
Aiph5u
(Aiph5u (not affiliated with Onefinity))
15
Hey Derek, hey all,
…and as stated above in the VFD manual, this is not enough for running a VFD.
However in a forum where people possibly buy chinese no-name spindles with the housing not internally connected to PE wire, I’d sleep more calmly if you have a RCD in all cases
Aiph5u
(Aiph5u (not affiliated with Onefinity))
16
Hey Kyle,
now I better understand your situation.
But generally I would try to have a RCD, but one with ratings that match running a VFD.
I rarely use this way to acquire information (I rather read my books) .
Remarks for using ground fault interrupter breakers in the main power supply:
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