57. Which of the following carrier frequency is used in a carrier current protection scheme?
A. 500 kHz to 5lcHz
B. 5 kHz to 50 kHz
C. 50 kHz to 500 kHz
D. 500 kHz to 5 MHz
58. The problem of stability occurs in
A. dc lines only
B. ac lines only
C. both dc and ac lines
D. none of these
59. Which of the following condition causes transient iqrstability in power system?
A. short circuit
B. switchng operations on the line
C. loss of excitation in a generator
D. all of these
60. Between the power house and consumer, there are usually a number of transformation and switching stations. These are called
A. transformer stations
B. intermediate stations
C. substations
D. switch gears
61. The condition necessary for transient stability is
A. j58 2(Ps ? Pe) d&0 o
B. 12 2(Ps ? P e)d6=0
C.2(Ps ? Pe )20
D.r s e d=0
62. Modern trend in rail electrification in India is to use which of the following supply system
A. 25 kV, 50 Hz
B. 15 kV, 50 Hz
C. 6 kV, 50 Hz
D. 6 kV, dc
63. Tractive force Fa needed to accelerate a train of effective mass M for providing acceleration a is given by
A. Fa = 277.8 Ma (N)
B. Fa = 277.8 Ma (kg)
C. Fa = Ma (N)
D. Fa = Ma (kg)
Page 9 of 54