What's a Counterpoise?
What's a Counterpoise?
(OP)
Does anyone have any information on what a counterpoise is?
When was the last time you drove down the highway without seeing a commercial truck hauling goods?
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RE: What's a Counterpoise?
RE: What's a Counterpoise?
RE: What's a Counterpoise?
That may also be correct. But commercial electrical contract drawings are on are full with so called standard grounding electrode details referred to as "counterpoise" as I described. It may or may not be appropirate but that is what most electrical contractors in commercial world understand.
It is possible that the term counterpoise is loosely applied there. As I undestand is "counterpoise" grounding electrode system has a closed loop versus radail conductors. Its roots possibly are in antenna grounding.
Question to OP is where did he/she find this term? What precipitated the question.
Here is a link that discusses "counterpoise".
http://www.antennex.com/shack/Dec06/cps.html
RE: What's a Counterpoise?
The earth electrode configuration has been adopted by power industry and the name has been taken over without much thinking about its real meaning.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: What's a Counterpoise?
RE: What's a Counterpoise?
RE: What's a Counterpoise?
The term is as I defined it in the IEEE Green Book. A typical ground grid would be in a substation with closed meshes. Typically counterpoise would be used on a transmission tower, especially if it is hard to drive ground rods. I don't know how common it is. I've always just used ground rods or used the tower pier foundations as a ufer ground.
Gunnar's explanation of the origins sounds right to me. I expect that the term is used for many different kinds of grounding electrodes in different applications. Try Googling it.
Any grounding electrode will help reduce GPR and counterpoise by any definition is a grounding electrode (or earthing).
RE: What's a Counterpoise?
RE: What's a Counterpoise?
RE: What's a Counterpoise?
A simple explanation - a counterpoise is an extension conductor that connects the main ground grid to a remote grid or a ground electrode. It typically runs along with a overhead line, e.g.skywire or ground wire, and it helps the main grid to dissipate a fualt current by parallelling more ground conductors to the grid, hence reduce the GPR.
RE: What's a Counterpoise?
RE: What's a Counterpoise?
Just to let you know on the use of the term "counterpoise" (in Portuguese is "contrapeso"), is common practice in my company (Chesf, Northeast of Brazil) to use "contrapeso" to improve transmission lines grounding, mainly those with concrete towers.
Regards,
Herivelto Bronzeado
RE: What's a Counterpoise?
The follwing is excerpt from standard guide specs used for building systems. It does not mean that it is the definition but it is very commonly used and understood term by electrical contractors in the USA. It is a misapplied term in my opinion.
"COUNTERPOISE: Ground the steel framework of the building as shown on plans. Provide a grounding conductor (counterpoise), electrically connected to each ground rod and to each steel column, extending around the perimeter of the building. Use copper conductor not less than No. 4/0 AWG for counterpoise and for welding to building steel. Bury counterpoise not less than 18 inches (450 mm) below grade and 24 inches (600 mm) from building foundation."
RE: What's a Counterpoise?
So, as I read the requirement, this is what the NEC and NFPA 780 call a ground ring. NEC 250.53 (F) requires a ground ring to be 750 mm (30 in.) deep. You only need 18 in. (457 mm) according to NFPA 780 ¶3.13.3, so I guess your guide spec is OK if it is for the lightning protection system (if you're using a meter stick instead of a yard stick, you need an extra 7 mm)
I have seen a substation construction specification that uses the term counterpoise for the wires in a station ground grid.
RE: What's a Counterpoise?
Inches to mm conversion factors are not mine! -:). The are in so called master specs. Thank US government for that or whosover thought of converting US to metric!! They are mandatory now in US Govt. specs (I stay away from Govt. work for the record.)
Yes, the word "ring" or "closed loop" is the key. Since that kind of mimics the topology of a true counterpoise antenna grounding grid, perhaps the term 'counterpoise' was borrowed by some power (more likely the Tower people, who would be the common link between the antenna work and the power work).
RE: What's a Counterpoise?
I always understood that a "counter-poise" was intended to improve the radiation characteristics of a radio transmission tower or antenna.
I would consider conductors radiating out from the base of an AM transmission tower to be a counter poise, as they affect the transmission of the signal.
I would consider the grid or ring around the base of a tower supporting cell phone antennas or something similar to be a ground grid or ground ring, as they are for safety grounding and intended primarily to limit touch and step potentials. The grounding has little or no effect on the radiated signal.
I believe that this distinction was valid years ago, but has been blured over the years by popular misusage.
Bill
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"Why not the best?"
Jimmy Carter