typical lengths. For analysis of power systems, the distributed resistance, series inductance, shunt leakage resistance and shunt capacitance can be replaced with suitable lumped values or simplified networks. Short and medium line model A short length of a power line (less than 80 km) can be approximated with a resistance in series with an inductance and ignoring the shunt admittances. This value is not the total impedance of the line, but rather the series impedance per unit length of line. For a longer length of line (80–250 km), a shunt capacitance is added to the model. In this case it is common to distribute half of the total capacitance to each side of the line. As a result, the power line can be represented as a two-port network, such as with ABCD parameters. The circuit can be characterized as where Z is the total series line impedance z is the series impedance per unit length l is the line length is the sinusoidal angular frequency The medium line has an additional shunt admittance where Y is the total shunt line admittance y is the shunt admittance per unit length See also Aerial cable Anchor portal Conductor marking lights CU project controversy Overhead cable Overhead line Raptor conservation Third rail Operation Outward Powerline river crossings in the United Kingdom Wireless monitoring of overhead power lines References Further reading William D. Stevenson, Jr. Elements of Power System Analysis Third Edition, McGraw-Hill, New York (1975) External links Electric power distribution