Capacitance of Three Phase Line with More Than One Circuit

Capacitance of Three Phase Line with More Than One Circuit

Consider the arrangement of conductors shown in the Fig. 1.33.1.

The voltage between phase a and b is given by,

Capacitance per phase will be nothing but 2 C_an.

Example 1.33.1 If the double circuit 3 phase line has conductors of diameter 2 cm and distance of separation 2 m in hexagonal spacing arrangement. Calculate phase to neutral capacitance for 100 km of line.

Solution :

Example 1.33.2 A 3 phase double circuit line is as shown in the Fig. 1.33.3. The diameter of each conductor is 2.5 cm. The line is transposed and carries balanced load. Determine the capacitance per phase to neutral of the line. Find the charging current per phase per km if line operates at 132 kV and 50 Hz.

Solution : Consider the arrangement of conductors shown in Fig. 1.33.3. It consists of three phase double circuit. The radius of each conductor is r.

The voltage between phases a and b can be calculated in order to calculate capacitance.

We have,

Now let us find the various distances from given problem

h = 7 m ; j = 8 m, dia - 2.5 cm, Radius r - 1.25 cm, d = 9 m

Review Question

1. Derive the expression of capacitance of a double circuit line for hexagonal spacing.

AU : May-04, Marks 9