The 60 mile, 115 kV line GH (Figure P12.8) is operating with the voltages at each end 30° out of phase when a three-phase fault occurs at 80% of the dis tance from bus G. This fault has 12 Ω arc resistance. The currents flowing to the fault are as shown and are in per unit at 100 MVA, 115 kV. a. Determine the apparent impedance seen by the distance relays at G for this fault. b. Determine if the zone 1 mho unit at G set for 90% of the line GH can operate on this fault. Assume that the angle of the mho characteristic (Figure 6.12b) is 75°. c. Determine the apparent impedance seen by the distance relays at H for this fault.
Synchronous Generator
In comparison to an asynchronous generator, it is a machine where the rotor speed is equal to the rotating magnetic field produced by the stator, i.e., mechanical speed is equal to the electrical speed, thus called synchronous, and not asynchronous.
Salient Pole Rotor
Salient pole rotor includes a large number of exposed poles mounted on a magnetic wheel. The construction of a bright pole is as shown in the image on the left. The proposed poles are made of metal laminations. The rotor winding is provided on these poles and is supported by pole shoes.
The 60 mile, 115 kV line GH (Figure P12.8) is operating with the voltages at
each end 30° out of phase when a three-phase fault occurs at 80% of the dis
tance from bus G. This fault has 12 Ω arc resistance. The currents flowing to
the fault are as shown and are in per unit at 100 MVA, 115 kV.
a. Determine the apparent impedance seen by the distance relays at G for
this fault.
b. Determine if the zone 1 mho unit at G set for 90% of the line GH can
operate on this fault. Assume that the angle of the mho characteristic
(Figure 6.12b) is 75°.
c. Determine the apparent impedance seen by the distance relays at H for this
fault.
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