### Power Quality And Management Set 2

This set of Power Quality and Management Multiple Choice Questions & Answers (MCQs) focuses on Power Quality And Management Set 2

Q1 | With 100% series compensation of lines
• the circuit is series resonant at power frequency
• low transient voltage
• high transient current
• (a) and (b)
Q2 | In a pure LC parallel circuit under resonance condition, current drawn from the supply mains is
• very large
• V ,FTE
• V /11-j
• Zero
Q3 | A lightning arrestor connected between the line and earth in a power system
• protects the terminal equipment against travelling surges
• protects the transmission line against lightning stroke
• suppresses high frequency oscillations in the line
• reflects back the travelling wave approaching it
Q4 | Lightning arresters are used in power systems to protect electrical equipments against
• direct strokes of lightning
• power frequency overvoltages
• overvoltages due to indirect lightning stroke
• overcurrents due to lightning stroke
Q5 | Consider the following statements : The transient stability of the power system under unbalanced fault conditions can be effectively improved by1. Excitation control2. phase-shifting transformer3. single-pole switching of circuit breakers4. increasing the turbine input. Of these statements
• 1 and 2 are correct
• 2 and 3 are correct
• 3 and 4 are correct
• 1 and 3 are correct
Q6 | One current transformer (CT) is mounted over a 3-phase 3-core cable with its sheath and armour removed from the portion covered by the CT. An ammeter placed in the CT secondary would measure
• the positive sequence current
• the negative sequence current
• the zero sequence current
• three times the zero sequence
Q7 | Earth wire on EHV overhead transmission line is provided to protect the lineagainst
• lightning surge
• switching surge
• excessive fault voltages
• corona effect
Q8 | The velocity of travelling wave through a cable of relative permittivity 9 is
• 9 x 108 m/s
• 3 x 108 m/s
• 108 m/s
• 2 x 108 ms
Q9 | A wave-trap is used at the termination of a HVAC overhead line to a station switchyard to
• prevent the transformer magnetising harritonics from reaching the overhead line
• damp the incoming surge waves from the overhead lines
• attenuate sub-harmonic oscillations
• provide for carrier communication
Q10 | Shunt compensation in an EHV line is used to improve
• stability and fault level
• fault level and voltage profile
• voltage profile and stability
• stability, fault level and voltage profile
Q11 | The principal information obtained from load flow studies in a power system are1. magnitude and phase angle of the voltage at each bus.2. reactive and real power flows in each of lines.3. total power loss in the network.4. Transient stability limit of the system Select the correct answer from the codes given below :
• I and 2
• 3 and 4
• 1,2 and 3
• 2 and 4
Q12 | While rising and while falling, if a wave is symmetrical, it contains
• even harmonics in addition to fundamental
• odd harmonics in addition to fundamental
• (b) both odd and even harmonics in addition to fundamental
• none of the above
Q13 | While rising and falling if a wave is not symmetrical, it contains
• even harmonics in addition to fundamental
• odd harmonics in addition to fundamental
• both odd and even harmonics in additions to fundamental
• none of the above
Q14 | The main reason for generation of harmonics in a transformer could be
• poor insulation
• mechanical vibrations
• saturation of core
Q15 | Harmonics in transformer result in
• increased core losses
• increased 12R losses
• magnetic interference with communication circuits
• all of the above
Q16 | Which fractional pitch will eliminate the seventh harmonic from the voltage waveform of an alternator?
• 07-Jun
• 08-Jul
• 06-May
• None of the above
Q17 | Most of the power quality problems are related to ______
• Transmission Issue
• Grounding Issue
• Distribution Issue
• all of the above
Q18 | Which of the following is not considered as good power quality voltage
• Power Supply is more compared to demand
• Constant sine wave
• Constant Velocity
• Constant RMS Value unchanged with time
Q19 | Lightening and Tree striking on a live conductor is an example________ PowerQuality issue.
• Voltage Sag
• Voltage Swell
• Interruption
• Surge
Q20 | Interruption is
• complete loss of power
• complete loss of voltage
• complete loss of current
• all the above
Q21 | The Transients in the power system occurs for
• less than two complete cycles
• exact two complete cycles
• less than one complete cycles
• exact one complete cycles
Q22 | The most common cause of long interruption is ______
• Faults
• Outages
• Both (a) & (b)
• none of the above
Q23 | Outage is the
• Removal of Primary Component
• (b) No Power Generation
• Transmission Faults
• (d) None of the above
Q24 | Single Phase Tripping is generally used in _________________.
• Transmission System
• Distribution System
• Low Voltage System
• Generation System
Q25 | The Short Interruptions occurs for
• Less than two complete cycles
• exact two complete cycles
• less than one complete cycles
• exact one complete cycles