Counterpoise
- Thread starter ME1
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bphgravity
Senior Member
- Location
- Florida
Not really, but a ground ring is sometimes called a counterpoise.
Counterpoise grounding consists of conductors buried below the surface of the earth that are connected to a power-system ground point. In the case of a transmission tower, the connection point could be the tower footing or the grounded side of a lightning arrestor. This counterpoise provides a relatively high capacitance and therefore a relatively low impedance path to earth. The counterpoise is sometimes used in medium- and low-frequency applications where it would be difficult to provide an effective ground connection.
The function of the counterpoise is to lower the transmission in areas where the impedance needs to be lowered. The reduction of impedance will reduce the insulator flashover due to lightning strikes. Since ground rods and mats have been found to be ineffective in high-resistivity soils, some utilities have implemented counterpoise grounding. It was found, for example, that in rural areas counterpoise provided some lightning protection, depending of course on soil resistivity. Since performance is directly dependant on field conditions, such as soil resistivity and homogeneity, the use of field measurements is required to ensure the effectiveness of counterpoise grounding.
Counterpoise is an effective means of reducing the impedance to ground presented to a lightning strike in areas where high soil resistivity and rocky ground prevent conventional grounding. Fundamentally, counterpoise, which should be considered an alternative to other methods of grounding, is a leaky transmission line that is intentionally connected to the earth with large amounts of conductance. At the instant of a lightning strike, the counterpoise acts as surge impedance mutually coupled with both the ground wires and phase conductors of the transmission line. The energy from the lightning strike travels down the counterpoise and is reflected at the terminal end. The counterpoise will act as a series resistance with a distributed leakage to ground.
A counterpoise would be in excess of a grounding electrode system, not in lieu of, or would be installed for the purposes of a LPS as indicated by you. But for nothing more than the ease of bonding all down conductors together.
Counterpoise grounding consists of conductors buried below the surface of the earth that are connected to a power-system ground point. In the case of a transmission tower, the connection point could be the tower footing or the grounded side of a lightning arrestor. This counterpoise provides a relatively high capacitance and therefore a relatively low impedance path to earth. The counterpoise is sometimes used in medium- and low-frequency applications where it would be difficult to provide an effective ground connection.
The function of the counterpoise is to lower the transmission in areas where the impedance needs to be lowered. The reduction of impedance will reduce the insulator flashover due to lightning strikes. Since ground rods and mats have been found to be ineffective in high-resistivity soils, some utilities have implemented counterpoise grounding. It was found, for example, that in rural areas counterpoise provided some lightning protection, depending of course on soil resistivity. Since performance is directly dependant on field conditions, such as soil resistivity and homogeneity, the use of field measurements is required to ensure the effectiveness of counterpoise grounding.
Counterpoise is an effective means of reducing the impedance to ground presented to a lightning strike in areas where high soil resistivity and rocky ground prevent conventional grounding. Fundamentally, counterpoise, which should be considered an alternative to other methods of grounding, is a leaky transmission line that is intentionally connected to the earth with large amounts of conductance. At the instant of a lightning strike, the counterpoise acts as surge impedance mutually coupled with both the ground wires and phase conductors of the transmission line. The energy from the lightning strike travels down the counterpoise and is reflected at the terminal end. The counterpoise will act as a series resistance with a distributed leakage to ground.
A counterpoise would be in excess of a grounding electrode system, not in lieu of, or would be installed for the purposes of a LPS as indicated by you. But for nothing more than the ease of bonding all down conductors together.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Whats the advantage of a ground ring for systems 600 V and under?
Its similar in installation to a counterpoise.
Its similar in installation to a counterpoise.
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