Has anyone had experience with connecting a 20 HP 480 volt 3 phase motor that is controlled by a VFD to a GFI circuit breaker? We are working on a new brewery. The electrical engineer specified a 480 volt cord drop for the owner to plug in a transfer pump. The owner wants us to mount a VFD on his portable motor cart. I am concerned that the VFD will cause the GFI breaker to trip. My local motor shop told me there is built in ground fault protection in the VFD.
GFI breaker connected to VFD
- Thread starter meichorst
- Start date
- Status
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
VFDs designed for the US marketplace and UL listed as "Motor Controllers" (as opposed to some of the bottom feeders who list them, but as "Power Conversion Equipment), are now required to provide the Motor Short Circuit and Ground Fault protection. But that is only for down stream of the VFD, not the supply side.
Also, this is NOT intended to be "personnel protection" GF, aka "Class A Ground Fault" if that was the intent of the requirement, it is "equipment" protection, or "GFPE". Most likely that was the case for your 480V breaker anyway, so if that's the case, the VFD will be doing the same thing.
Most likely there will be common mode noise associated with a VFD on a portable cart because it's hard to provide proper grounding, so it's likely to create nuisance tripping situations on a breaker with GF trips.
7EA
Member
- Location
- California
I recently had to connect a couple of small tank mixer motors to VFD's with 120v 1 ph supply. The idea was that they could be moved throughout the plant and plugged into standard convienence outlets. They tripped every GFI outlet and GFI breaker that we tried. After reading the fine print (funny how you do that after things don't work) the VFD manual told me the same information that I now know! Most 120v or "residential" GFI's will trip at 5 ma and "industrial" devices have a somewhat higher trip setting for greater allowance for "leakage current". Perhaps researching something like this Littlefuse product will yield some answers.
http://www.littelfuse.com/~/media/F...use_IndustrialShockblock_SB6000_Datasheet.pdf
http://www.littelfuse.com/~/media/F...use_IndustrialShockblock_SB6000_Datasheet.pdf
texie
Senior Member
- Location
- Fort Collins, Colorado
- Occupation
- Electrician, Contractor, Inspector
You might want to talk to these folks as they are well versed in all things GFCI, GFP, ground monitors, etc. http://www.bender-us.com/solutions/gfci.aspx
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
There are three types of protection that often are confused- Class A GFCI is the one required by 210.8 locations, it is for personnel protection and has a trip point in the 4-6 mA range. Class B GFCI is for equipment protection and may have trip point of 100 mA.
Then there is the "ground fault protection" on certain systems that has more to do with keeping the equipment from burning up during a fault than it has to do with responding to a low current ground fault.
There is no requirement in 210.8 for any kind of "GFCI" protection on a circuit operating at 480 volts.
OP: exactly which kind of device are you dealing with?
Then there is the "ground fault protection" on certain systems that has more to do with keeping the equipment from burning up during a fault than it has to do with responding to a low current ground fault.
There is no requirement in 210.8 for any kind of "GFCI" protection on a circuit operating at 480 volts.
OP: exactly which kind of device are you dealing with?
StarCat
Industrial Engineering Tech
- Location
- Moab, UT USA
- Occupation
- Imdustrial Engineering Technician - HVACR Electrical and Mechanical Systems
?20 HP
?20 HP
First thing the information given by KWIRED and JRAEF is always first rate.
Possibly you mean 2 HP rather than 20?
I have never seen that large of a portable pump for this application in Brewery operations.
Also there is a major anount of overkill on this front of portable cart pumps along with the evident over engineering on the electrical end.
A 1 HP 115v pump will deal adequately with vertical vessels up to 30 BBL easily.
?20 HP
First thing the information given by KWIRED and JRAEF is always first rate.
Possibly you mean 2 HP rather than 20?
I have never seen that large of a portable pump for this application in Brewery operations.
Also there is a major anount of overkill on this front of portable cart pumps along with the evident over engineering on the electrical end.
A 1 HP 115v pump will deal adequately with vertical vessels up to 30 BBL easily.
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