### Power Quality And Management Set 1

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 :
• 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)