B
- Status
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
They are all symbols for a 'ground' connection.
The electrical industry has very few universal symbols especially for 'bonding to a reference', so global instruction manuals will usually include the most common ones.
The electrical industry has very few universal symbols especially for 'bonding to a reference', so global instruction manuals will usually include the most common ones.
Speedskater
Senior Member
- Location
- Cleveland, Ohio
- Occupation
- retired broadcast, audio and industrial R&D engineering
In electronics the word "ground" has many meanings, most have nothing to do with Mother Earth.
While Henry W. Ott has a better definition, but let's start with:
"A common reference point"
In electronics we often see:
Signal, analog, digital, circuit and chassis grounds.
In your chart:
Chassis ground is the upper right symbol
"PE" or Protective Earth is the European EGC
While Henry W. Ott has a better definition, but let's start with:
"A common reference point"
In electronics we often see:
Signal, analog, digital, circuit and chassis grounds.
In your chart:
Chassis ground is the upper right symbol
"PE" or Protective Earth is the European EGC
B
bthielen
Guest
According to my NFPA 79 booklet the symbol that looks like a garden rake represents equipotential bonding. Am I correct that this does not necessarily mean grounded so this symbol may not be indicating a point that is common with earth ground?
Also, the symbol that employs a triangle is used for the dc common terminal on the I/O terminal strip. The drive provides 24vdc signalling start/stop/forward/reverse etc. Would I be correct that the user dc may not be grounded and therefore could be a floating dc?
The remaining three symbols seem to represent the same thing in the VFD manual. The one in the middle with the circle around it is very similar to the symbol in my NFPA 79 booklet that is supposed to represent "functional earthing." NFPA 79 shows only the top half of the circle rather than a complete circle. The letters PE are identified wherever this symbol is used in the manual. I suspect it is safe to say that these terminations are common and that we need to provide the connection to earth ground. Does that sound reasonably accurate?
Also, the symbol that employs a triangle is used for the dc common terminal on the I/O terminal strip. The drive provides 24vdc signalling start/stop/forward/reverse etc. Would I be correct that the user dc may not be grounded and therefore could be a floating dc?
The remaining three symbols seem to represent the same thing in the VFD manual. The one in the middle with the circle around it is very similar to the symbol in my NFPA 79 booklet that is supposed to represent "functional earthing." NFPA 79 shows only the top half of the circle rather than a complete circle. The letters PE are identified wherever this symbol is used in the manual. I suspect it is safe to say that these terminations are common and that we need to provide the connection to earth ground. Does that sound reasonably accurate?
- Location
- Bremerton, Washington
PE is an European term meanging protective earth. The grounding schemes used in locations not under the NEC are different, and it may not be possible to make a direct correlation to our use of ground and bond.
The only thing you know for sure is that the nodes with the same symbol are connected together.
There is also
http://en.wikipedia.org/wiki/Ground_(electricity)
Single point grounds, which only show up on wiring diagrams and not on schematics, are sometimes essential for the thing to operate properly. I saw one in a receiver; a two inch chunk of heavy wire bolted to the chassis with black wires coming to it from all over the chassis.
Electrical functioning and personal safety are two different things.
There is also
http://en.wikipedia.org/wiki/Ground_(electricity)
Single point grounds, which only show up on wiring diagrams and not on schematics, are sometimes essential for the thing to operate properly. I saw one in a receiver; a two inch chunk of heavy wire bolted to the chassis with black wires coming to it from all over the chassis.
Electrical functioning and personal safety are two different things.
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No.
With the bottom three alone yes. But the top two can go either way. I do not mean user's choice. It is whichever way the designer or manufacturer says it is, or whichever way the overiding standard or authority says it will be.
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hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Top line:
Signal ground, ghosts/invisible ground, chassis ground.
Bottom line:
Common Earth ground, technical earth ground, protective earth ground.
Signal ground, ghosts/invisible ground, chassis ground.
Bottom line:
Common Earth ground, technical earth ground, protective earth ground.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Cute.
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bthielen
Guest
I wasn't very clear. I was referring to the bottom three in my diagram when I made that statement. Sorry.
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