Power Quality And Management Set 1

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This set of Power Quality and Management Multiple Choice Questions & Answers (MCQs) focuses on Power Quality And Management Set 1

Q1 | Non-sinusoidal waveforms are made of
  • different sinusoidal waveforms
  • fundamental and even harmonics
  • fundamental and odd harmonics
  • even and odd harmonics only
Q2 | The positive and negative halves of a complex wave are symmetrical when
  • it contains even harmonics
  • phase difference between even harmonics and fundamentals is 0 or it
  • it contains odd harmonics
  • phase difference between even harmonics and fundamental is either n/2 or 3n/2
Q3 | The rms value of the complex voltage given by v = 161i sin cot + 12 Ari sin Rot is
  • 20 Ari
  • 20
  • 28
  • 192
Q4 | In a 3-phase system,the harmonic has negative phase sequence of RBY.
  • 9
  • 13
  • 5
  • 15
Q5 | Two complex waves will have the same wave-shape if
  • they contain the same harmonics
  • ratio of corresponding harmonics to their respective fundamentals is the same
  • harmonics are similarly spaced with respect to their fundamental
  • they have all of the above
Q6 | The trigonometric Fourier series for a complex wave will contain positive cosineterms only when
  • it contains even harmonics
  • its two half-cycles are symmetrical
  • its value is zero at 0= n/2, 3n/2 etc.
  • its value is zero at 0= n, 2n etc.
Q7 | Tansient disturbance is produced in a circuit whenever
  • it is suddenly connected or discon nected from the supply
  • it is shorted
  • its applied voltage is changed suddenly
  • all of the above
Q8 | There are no transients in pure resistive circuits because they
  • offer high resistance
  • obey Ohm's law
  • have no stored energy
  • are linear circuits
Q9 | Transient current in electrical circuits are associated with
  • inductors
  • capacitors
  • resistors
  • both (a) and (b)
Q10 | The transients which are produced due to sudden but energetic changes from onesteady state of a circuit to another are called transients.
  • initiation
  • transition
  • relaxation
  • subsidence
Q11 | In an R-L circuit connected to an alternating sinusoidal voltage, size of transient current primarily depends on
  • the instant in the voltage cycle at which circuit is closed
  • the peak value of the steady-state current
  • the circuit impedance
  • the voltage frequency
Q12 | Double-energy transients are produced in circuits consisting of
  • two or more resistors
  • resistance and inductance
  • resistance and capacitance
  • resistance, inductance and capacitance
Q13 | The transient current in a loss-free L-C circuit when excited from an ac source isa/an sine wave.
  • over-damped
  • undamped
  • under-damped
  • critically damped
Q14 | Transient current in an R-L-C circuit is oscillatory when
  • R =0
  • R> 2f-17
  • R <2
  • R =2
Q15 | For measuring positive, negative and zero sequence voltages in a system, thereference is taken as :
  • Neutral of the system only
  • Ground only
  • For zero sequence neutral and for positive and negative the ground
  • None of the above
Q16 | The most economic load on an underground cable is :
  • Greater than its surge loading
  • Less thart the surge loading
  • Equal to the surge loading
  • None of the above is necessary
Q17 | In case of a 3-phase short circuit is a system, the power fed into the system is :
  • Mostly reactive
  • Mostly active
  • Active and reactive both equal
  • Reactive only
Q18 | An RLC series circuit remains predominantly inductive :
  • At resonance frequency
  • Below resonance frequency
  • Above resonance frequency
  • At the lower half power frequency
Q19 | A generator is connected to a synchronous motor. From stability point of view it is preferable to have :
  • Generator neutral reactance grounded and motor neutral resistance grounded
  • Generator and motor neutrals resistance grounded
  • Generator and motor neutrals reactance grounded
  • Generator neutral resistance and motor neutral reactace grounded
Q20 | The positive sequency component of voltage at the point of fault is zero when it is a :
  • 3-phase fault
  • L-L fault
  • L-L-G fault
  • L-G fault
Q21 | Tick out the correct statement :
  • The negative and zero sequence voltages are maximum at the fault point and decreases towards the neutral
  • The negative and zero sequence voltages are minimum at the fault point and increase towards the neutral
  • The negative sequence is maximum and zero sequence minimum at the fault point and decrease and increase respectively towards the neutral.
  • None of the above
Q22 | The order of the lightning discharge current is :
  • 10,000 amp
  • 100 amp
  • 1 amp
  • 1 microampere
Q23 | The magnetising-inrush-current in a transformer is rich in :
  • 3rd harmonics
  • 5th harmonics
  • 7th harmonics
  • 2nd harmonics
Q24 | The in-rush current of a transformer at no load is maximum if the supply voltage isswitched on
  • At zero voltage value
  • At peak voltage value
  • At V/2 value
  • At ,6 /2V value
Q25 | Pure inductive circuit takes power (reactive) from the a.c. line when
  • both applied voltage and current rise
  • both applied voltage and current decrease
  • applied voltage decreases but current increases
  • (a) and (b)