Power Quality And Management Set 1 MCQs

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)