Power Systems T...

In a system of 132 kV, the circuit phase to ground capacitance is 0.02 μF, the inductance is 5 H. If a magnetic circuit of 8 A is interrupted instantaneously, the value of the pre-insertion resistor to be used across the contact space is _____ (in kΩ)

The rated making current of a circuit breaker is given as 90 kA (peak). The braking capacity (in MVA) of circuit breaker if it is rated at 22 kV

A 10-ampere, over current relay having a current setting of 150% and a time setting multiplier of a 0.8 connected to supply circuit through a 400/5 current transformer when the circuit carries a fault current of 5000 A. Find the plug-setting multiplier.

The short circuit current of a 132 kV system is 8000 A. The current chopping occurs at 2.5% of peak value of current. The value of stray capacitance to the earth is 100 pF. The inductance is 30 mH. The prospective value of the voltage which coil appear across the contacts of the circuit breakers is _______ (in kV)

In short circuit test on a 3 pole, 132 kV circuit breaker, the following observations are made:

Power factor of fault = 0.4

Recovery voltage is 0.9 times the full line value.

The breaking current is symmetrical, frequency of the oscillations of restriking voltage is 16 kHz. If both neutral and fault are grounded, the a value of average RRRV is _______ (in kV/μ sec)

In a 132 kV, 50 Hz system, reactance and capacitance up to the location of the circuit breaker is 5 Ω and 0.02 μF respectively. A resistance of 500 Ω is connected across the breaker of the circuit breaker. The damped frequency of oscillation is ______ (in kHz)

A 3 phase, 15 MVA, 13 kV, star connected alternator is protected by current balancing system of protection. If the ratio of CT is 1500/4, the minimum operating current of the relay is 0.8 A and the neutral point resistance is 4 Ω. The percentage of each phaser of stator winding which is unprotected against faults when the machine is operating at normal voltage is _______ (in %)

An 11 kV, 100 MVA alternator is provided with differential protection. The percentage of winding to be protected against phase to ground fault is 85%. The relay is set to operate when there is 20% out of balance current. The value of the resistance (in ohms) to be placed in the neutral to ground connection is