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This set of Switch Gear and Protection Multiple Choice Questions & Answers (MCQs) focuses on Switch Gear And Protection Set 1
Q1 | The main function of a fuse is to
- protect the line
- open the circuit
- protect the appliance
- prevent excessive currents
Q2 | On which of the following routine tests are conducted?
- Oil circuit breakers
- Air blast circuit breakers
- Minimum oil circuit breakers
- All of the above
Q3 | SF6 gas
- is yellow in colour
- is lighter than air
- is nontoxic
- has pungent small
Q4 | The arcing contacts in a circuit breaker are made of
- copper tungsten alloy
- porcelain
- electrolytic copper
- aluminium alloy
Q5 | Which of the following medium is employed for extinction of arc in aircircuit breaker ?
- Water
- Oil
- Air
- SF6
Q6 | With which of the following, a circuit breaker must be equipped for remote operation ?
- Inverse time trip
- Time-delay trip
- Shunt trip
- None of the above
Q7 | Fault diverters are basically
- fuses
- relays
- fast switches
- circuit breakers
Q8 | A thermal protection switch can protect against
- short-circuit
- temperature
- overload
- over voltage
Q9 | Arc in a circuit behaves as
- a capackive reactance
- an inductive reactance
- a resistance increasing with voltage rise across the arc
- a resistance decreasing with voltage rise across the arc
Q10 | Thermal circuit breaker has
- delayed trip action
- instantaneous trip action
- both of the above
- none of the above
Q11 | Relays can be designed to respond to changes in
- resistance, reactance or impedance
- voltage and current
- light intensity
- all above
Q12 | Overload relays are of…… type.
- induction
- solid state
- thermal
- all above
Q13 | Thermal overload relays are used to protect the motor against overcurrent due to
- short-circuits
- heavy loads
- grounds
- all of the above
Q14 | Magnetic circuit breaker has ______ trip action.
- delayed
- instantaneous
- both of the above
- none of the above
Q15 | D.C. shunt relays are made of
- few turns of thin wire
- few turns of thick wire
- many turns of thin wire
- many turns of thick wire
Q16 | The relay operating speed depends upon
- the spring tension
- the rate of flux built up
- armature core air gap
- all of the above
Q17 | In order that current should flow without causing excessive heating orvoltage drop, the relay contacts should
- have low contact resistance
- be clean and smooth
- be of sufficient size and proper shape
- have all above properties
Q18 | Circuit breakers usually operate under
- transient state of short-circuit current
- sub-transient state of short-circuit current
- steady state of short-circuit current
- after D.C. component has ceased
Q19 | Circuit breakers are essentially
- current carrying contacts called electrodes
- arc extinguishers
- circuits to break the system
- tr
Q20 | The current zero interruption, in oil and air blast circuit breakers, is achieved by
- lengthening of the gap
- cooling and blast effect
- both (a) and (b)
- deionizing the oil with forced air
Q21 | Air blast circuit breaker is used for
- over currents
- short duty
- intermittant duty
- repeated duty
Q22 | An efficient and a well designed protective relaying should have
- good selectivity and reliability
- economy and simplicity
- high speed and selectivity
- all of the above
Q23 | Burden of a protective relay is the power
- required to operate the circuit breaker
- absorbed by the circuit of relay
- developed by the relay circuit
- none of the above
Q24 | Directional relays are based on flow of
- power
- current
- voltage wave
- all of the above
Q25 | A differential relay measures the vector difference between
- two currents
- two voltages
- two or more similar electrical quantities
- none of the above