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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)