Top 80+ Solved Power Quality and Management MCQ Questions Answer
Q. The most economic load on an underground cable is :
a. Greater than its surge loading
b. Less thart the surge loading
c. Equal to the surge loading
d. None of the above is necessary
Q. In case of a 3-phase short circuit is a system, the power fed into the system is :
a. Mostly reactive
b. Mostly active
c. Active and reactive both equal
d. Reactive only
Q. An RLC series circuit remains predominantly inductive :
a. At resonance frequency
b. Below resonance frequency
c. Above resonance frequency
d. At the lower half power frequency
Q. A generator is connected to a synchronous motor. From stability point of view it is preferable to have :
a. Generator neutral reactance grounded and motor neutral resistance grounded
b. Generator and motor neutrals resistance grounded
c. Generator and motor neutrals reactance grounded
d. Generator neutral resistance and motor neutral reactace grounded
Q. The positive sequency component of voltage at the point of fault is zero when it is a :
a. 3-phase fault
b. L-L fault
c. L-L-G fault
d. L-G fault
Q. Tick out the correct statement :
a. The negative and zero sequence voltages are maximum at the fault point and decreases towards the neutral
b. The negative and zero sequence voltages are minimum at the fault point and increase towards the neutral
c. The negative sequence is maximum and zero sequence minimum at the fault point and decrease and increase respectively towards the neutral.
d. None of the above
Q. The order of the lightning discharge current is :
a. 10,000 amp
b. 100 amp
c. 1 amp
d. 1 microampere
Q. The magnetising-inrush-current in a transformer is rich in :
a. 3rd harmonics
b. 5th harmonics
c. 7th harmonics
d. 2nd harmonics
Q. The in-rush current of a transformer at no load is maximum if the supply voltage isswitched on
a. At zero voltage value
b. At peak voltage value
c. At V/2 value
d. At ,6 /2V value
Q. Pure inductive circuit takes power (reactive) from the a.c. line when
a. both applied voltage and current rise
b. both applied voltage and current decrease
c. applied voltage decreases but current increases
d. (a) and (b)
Q. With 100% series compensation of lines
a. the circuit is series resonant at power frequency
b. low transient voltage
c. high transient current
d. (a) and (b)
Q. In a pure LC parallel circuit under resonance condition, current drawn from the supply mains is
a. very large
b. V ,FTE
c. V /11-j
d. Zero
Q. A lightning arrestor connected between the line and earth in a power system
a. protects the terminal equipment against travelling surges
b. protects the transmission line against lightning stroke
c. suppresses high frequency oscillations in the line
d. reflects back the travelling wave approaching it
Q. Lightning arresters are used in power systems to protect electrical equipments against
a. direct strokes of lightning
b. power frequency overvoltages
c. overvoltages due to indirect lightning stroke
d. overcurrents due to lightning stroke
Q. Consider the following statements : The transient stability of the power system under unbalanced fault conditions can be effectively improved by 1. Excitation control 2. phase-shifting transformer 3. single-pole switching of circuit breakers 4. increasing the turbine input. Of these statements
a. 1 and 2 are correct
b. 2 and 3 are correct
c. 3 and 4 are correct
d. 1 and 3 are correct