IOC Electrical
Low voltage cables are generally use up to A)1.1kV B)3.3kV C)6.6kV D)11kV
A)1.1kV
If a feeder with circuit breaker and isolator is to be switched OFF in loaded condition, which of the following is correct switching OFF sequence? A)1st Breaker, 2nd Isolator B)Both at the same time C)1st Isolator, 2nd Breaker D)None of these
A)1st Breaker, 2nd Isolator
ACDB fuse rating is of _____ % of designed fuse rating A)20 B)30 C)40 D)50
A)20
The contact resistance of a circuit breaker is of the order A)20 micro ohms ± 10 B)20milli ohms ± 10 C)20 ohms ± 10 D)200 ohms ± 10
A)20 micro ohms ± 10
In Real case, the Charging current for 200Ah battery would be A)20-22 A B)14-16 A C)12-14 A D)10-12 A
A)20-22 A
A delta/star transformer is connected in parallel to a star/delta transformer. The turn ratio of former is x times latter, the x is A)3 B)43468 C)√3 D)1/√3
A)3
For better reliability, a numeric under voltage protection relay shall be configured for A)3-Ph U/V Protection B)1-Ph U/V Protection C)Any of these D)None of these
A)3-Ph U/V Protection
The number of electrical degrees passed through in one revolution of a four pole synchronous alternator is A)360° B)720° C)1440° D)2880°
A)360°
To provide 3 Phase overcurrent & measured E/F protection through numeric relay, how many minimum CT coils are required in a relay? A)4 B)3 C)Depends on how many CTs are installed in switchgear D)Not possible to provide this combination of protection
A)4
The reactive power output of a synchronous generator is limited by A)Armature current and field current B)Field current and load angle C)Load angle and prime mover input D)Armature current and prime mover input
A)Armature current and field current
When a numeric relay is drawn out of casing A)CT terminals are shorted automatically B)Digital O/P terminals get shorted automatically C)All Digital I/P terminals get shorted automatically D)All of these
A)CT terminals are shorted automatically
Brushes of D.C. machines are made of A)Carbon B)Soft copper C)Hard copper D)All options are correct
A)Carbon
An ideal diode is one which behaves as a perfect _____ when forward biased A)Conductor B)Insulator C)Resistance material D)None of the above
A)Conductor
Arcing contacts in a circuit breaker are made of A)Copper tungsten alloy B)Porcelain C)Electrolytic copper D)Aluminum alloy
A)Copper tungsten alloy
How reduction in core losses and increase in permeability can be obtained simultaneously in a transformer? A)Core built-up of laminations of cold rolled grain oriented steel B)Core built-up of laminations of hot rolled sheet C)Cannot be determined D)Frequency Meter
A)Core built-up of laminations of cold rolled grain oriented steel
In a series circuit which of the following quantity remains same? A)Current B)Voltage C)Both current and voltage D)None of the above
A)Current
If the terminal voltage of an induction motor is decreased then current A)Decreased B)Increased C)Remain same D)None of the options are correct
A)Decreased
During discharging the specific gravity of the electrolytes of a lead acid battery A)Decreases B)Increases C)Remain same D)None of the above
A)Decreases
DAVR modifies A)Excitation of generator B)Speed of generator C)Power of generator D)None
A)Excitation of generator
In normal operation FCBC is in A)Float mode B)Boost mode C)Both D)None
A)Float mode
Motor mounting arrangement B3 denotes A)Foot Mounting B)Flange Mounting C)Both option 1 &2 are correct D)None of the options are correct
A)Foot Mounting
Losses which occur in rotating electric machines and do not occur in transformer are A)Friction and windage losses B)Magnetic losses C)Hysteresis and eddy current losses D)Copper losses
A)Friction and windage losses
In a given transformer for a given applied voltage, which losses remain constant irrespective of load changes? A)Hysteresis and eddy current losses B)Friction and windage losses C)Copper losses D)Cannot be determined
A)Hysteresis and eddy current losses
Silicon steel used in laminations, because it reduces A)Hysteresis loss B)Eddy current losses C)Copper losses D)Cannot be determined
A)Hysteresis loss
Which of the following is correct? I. Leakage reactance is dependent on supply current. II. Magnetizing reactance is dependent on the air gap flux A)I,II B)II C)I D)None of the mentioned
A)I,II
What is applicable IEC standard for design of HT switchboards? A)IEC-62271 B)IEC-60076 C)IEC-60034 D)IEC-60502
A)IEC-62271
What is applicable IS standard for design of HT switchboards? A)IS-12729 B)IS-2026 C)IS-325 D)IS-7098
A)IS-12729
As the speed of an alternator increases, the frequency A)Increases B)Decreases C)Remains constant D)May increases or decreases depending on the power factor
A)Increases
Due to sulphation effect in lead acid battery, its terminal resistance A)Increases B)Decreases C)Remain same D)None of the above
A)Increases
Speed control is possible for _____ and not possible for _____ A)Induction motor, synchronous motor B)Induction motor, differential motor C)Synchronous motor, synchronous-induction motor D)Dc motor, induction motor
A)Induction motor, synchronous motor
Crest factor is ratio between A)Instantaneous peak current required by the load and the RMS current B)Rms current required by the load and the instantaneous peak current C)Rms value and average value D)Peak value and average value
A)Instantaneous peak current required by the load and the RMS current
Which of the following is NOT true for VAJH-23 relay? A)It is a self-reset relay B)It is a hand reset relay C)It has 2 nos. of coils D)None of these
A)It is a self-reset relay
The disadvantage with paper as insulating material is A)It is hygroscopic B)It has high capacitance C)It is an organic material D)None of the above
A)It is hygroscopic
A transformer can have zero voltage regulation at A)Leading power factor B)Lagging power factor C)Unity power factor D)Zero power factor
A)Leading power factor
The no load current of the induction motor is high due to A)Long and high reluctance path between stator and rotor B)Mutual flux having moderate reluctance path between stator and rotor C)Leakage flux having low reluctance iron core D)Leakage flux having high reluctance iron core
A)Long and high reluctance path between stator and rotor
While a transformer is energized, the differentially connected relay may A)Mal operate B)Not mal operate C)Mal operate for lagging loads D)Never mal operate
A)Mal operate
A synchronous machine is operating at constant load and at unity power factor. If its excitation is increased and then it operates as A)Motor at leading p.f B)Motor at lagging p.f C)Absorber of reactive power D)Generator at leading p.f
A)Motor at leading p.f
Given two motors, (a) 375 rpm synchronous motor and (b) 1500 rpm induction motor of same power & voltage rating, which of the statement is true? A)Motor will have bigger diameter B)Motor will have smaller diameter C)Both motors will be same in dimensions D)None of these
A)Motor will have bigger diameter
The no load current of the transformer is very less due to A)Mutual flux having low reluctance iron core B)Mutual flux having high reluctance iron core C)Leakage flux having low reluctance iron core D)Leakage flux having high reluctance iron core
A)Mutual flux having low reluctance iron core
Normal transformers are designed to have maximum efficiency at A)Nearly full load B)70% full load C)50% full load D)No load
A)Nearly full load
EX nA motors are A)Non sparking motors B)Increased safety motors C)Pressurized motors D)Flameproof motors
A)Non sparking motors
The output frequency of an alternator depends on A)Number of poles and rotational speed B)Rotational speed only C)Numbers of poles only D)Types of winding
A)Number of poles and rotational speed
A semiconductor diode has A)One PN junction B)Two PN junction C)Three PN junction D)Four PN junction
A)One PN junction
Which of the following can be done using a synchronous motor but not by induction motor? A)Power factor improvement B)Supplying mechanical load C)Power factor improvement and supply mechanical load D)None of the mentioned
A)Power factor improvement
In the cables, sheaths are used to A)Prevent the moisture from entering the cable B)Provide enough strength C)Provide proper insulation D)None of the above
A)Prevent the moisture from entering the cable
The voltage appearing across the contacts of the CB after opening the circuit breaker is called A)Recovery voltage B)Surge voltage C)Operating voltage D)Arc voltage
A)Recovery voltage
If PT secondary fuse of 1-Phase wired to 3-Ph voltage & frequency relay blows off, which of the following statements is TRUE? A)Relay will measure less positive sequence voltage B)Relay will measure less frequency C)Relay will measure less positive sequence voltage & less frequency both D)None of these
A)Relay will measure less positive sequence voltage
If an unbalanced supply is fed to an induction motor, it will cause excessive heating of A)Rotor B)Stator C)Rotor shaft D)All of the mentioned
A)Rotor
In order to Increase voltage, number of cells are connected in A)Series B)Parallel C)Opposite direction D)None of the above
A)Series
The magnetization current drawn from an AC supply, a synchronous motor is used to _____ A)Set up flux in magnetic circuit of device B)Compensate core losses C)Set up magnetizing armature reaction D)All of the mentioned
A)Set up flux in magnetic circuit of device
Distribution transformers have A)Smaller size than Power transformer B)Larger size than power transformers C)Size can be more or less depending on type D)More weight than power transformers
A)Smaller size than Power transformer
The rotor of 3-phase slip ring induction motor is fed from a 3-phase supply with its stator winding short circuited having rotor rotating clockwise at a speed of Nr, then A)Speed of air gap field w.r.t. stator is Ns-Nr anticlockwise B)Speed of air gap field w.r.t. stator is Ns-Nr clockwise C)Speed of airgap field w.r.t rotor is Ns clockwise D)Speed of airgap field w.r.t. stator is Ns-Nr clockwise
A)Speed of air gap field w.r.t. stator is Ns-Nr anticlockwise
The torque in an induction motor varies as _____ and in synchronous motor as _____ A)Square of voltage, proportion to voltage B)Proportion to voltage, proportion to voltage C)Proportion to voltage, square of voltage D)Square of voltage, square of voltage
A)Square of voltage, proportion to voltage
Which of the following component is usually fabricated out of silicon steel? A)Stator core B)Bearings C)Shaft D)None of the options are correct
A)Stator core
Generator transformers are A)Step-up transformers B)Step-down transformers C)Auto-transformers D)One-one transformers
A)Step-up transformers
No load current in induction motor is 10-20% of full load current and the no load current of transformer is 2-6% A)TRUE B)FALSE C)Vary D)None of the above
A)TRUE
SCADA is an acronym that stands for Supervisory Control and Data Acquisition A)TRUE B)FALSE C)Vary D)None of the above
A)TRUE
SCADA refers to a system that collects data from various sensors at a factory, plant or in other remote locations and then sends this data to a central computer which then manages and controls the data A)TRUE B)FALSE C)Vary D)None of the above
A)TRUE
Single core cables for AC systems are not provided with armouring A)TRUE B)FALSE C)Vary D)None of the above
A)TRUE
What is "Make time" of a circuit breaker? A)Time interval from the energization of the solenoid to the instant of making contact for current establishment during closing of circuit breaker B)Time interval from the separation of contact to the extinction of the arc C)Time interval from the energization of the trip coil to the instant of contact separation D)Sum of the opening time interval and the arcing time interval
A)Time interval from the energization of the solenoid to the instant of making contact for current establishment during closing of circuit breaker
In a power or distribution transformer about 10 per cent end turns are heavily insulated A)To withstand the high voltage due to line surge produced by the shunting capacitance of the end turns B)To absorb the line surge voltage and save the winding of transformer from damage C)To reflect the line surge and save the winding of a transformer from damage D)Insufficient information
A)To withstand the high voltage due to line surge produced by the shunting capacitance of the end turns
An induction motor can be said analogous to A)Transformer B)Synchronous motor C)Universal motor D)Stepper motor
A)Transformer
A 3-phase induction motor with its rotor blocked behaves similar to a A)Transformer under short circuit of secondary terminals B)Transformer under open circuit of secondary C)Synchronous motor under slip test D)Synchronous motor under open circuit
A)Transformer under short circuit of secondary terminals
Burden of a protective relay is measured in A)VA B)VAR C)WATT D)None of the above
A)VA
Ladder logic programming consists primarily of: A)Virtual relay contacts and coils B)Logic gate symbols with connecting lines C)Function blocks with connecting lines D)Text-based code
A)Virtual relay contacts and coils
AVR maintains generator's _____ constant A)Voltage B)Frequency C)Power D)Load
A)Voltage
Which cable has higher overloading capacity A)Xlpe B)PVC C)Both D)None
A)Xlpe
Arc in a circuit breaker is interrupted at A)Zero Current B)Maximum current C)Minimum voltage D)Maximum voltage
A)Zero Current
Which is more hazardous area? A)Zone 0 B)Zone1 C)Zone2 D)Zone 3
A)Zone 0
Which of following zones is not suitable for motors? A)Zone 0 B)Zone1 C)Zone 2 D)Zone 3
A)Zone 0
Which zone contains continuous explosive atmosphere? A)Zone 0 B)Zone1 C)Zone 2 D)Zone 3
A)Zone 0
In Ideal case, the Charging Time for 200Ah battery would be A)5 hours B)10 hours C)15 hours D)20 hours
B)10 hours
A 10 pole AC generator rotates at 1200 rpm. The frequency of AC voltage in cycles per second will be A)120 B)100 C)160 D)60
B)100
In a three-phase half wave diode rectifier using 3 diodes, each diode conducts for A)90 degrees B)120 degrees C)180 degrees D)360 degrees
B)120 degrees
Standard open circuit voltage for Lead-acid battery at standard conditions is A)3 Volts B)2.048 Volts C)2.50 Volts D)3.508 Volts
B)2.048 Volts
Which of the following correctly specifies test parameters for power frequency high voltage test of a 11KV switchboard for the first time? A)11KV for 1 hour B)28 KV for 1 min C)22KV for 2 mins D)75KV for 1 Sec
B)28 KV for 1 min
Transformer magnetic inrush current mostly consists of A)Fundamental component B)2nd harmonic component C)3rd harmonic component D)5th harmonic component
B)2nd harmonic component
To provide 3 Phase overcurrent & derived E/F protection through numeric relay, how many minimum CT coils are required in a relay? A)4 B)3 C)Depends on how many CTs are installed in switchgear D)Not possible to provide this combination of protection
B)3
Angle of Zone of protection of Lightning Protection system is approximately: A)20 degree B)45 degree C)70 degree D)10 degree
B)45 degree
Operating time of a fuse for 20 times or higher than rated current is typically A)<5 ms B)<10 ms C)<20 ms D)<40 ms
B)<10 ms
Generally motors above which rating are to be fed through circuit breaker as per IOCL RTF recommendations A)> 11KW B)> 55KW C)< 55KW D)All motors
B)> 55KW
Which of the following statements is false? A)A Leclanché cell is suitable for use in torches B)A nickel-cadmium cell is an example of a primary cell C)A secondary cell may be recharged after use D)When a cell is being charged its terminal p.d. exceeds the cell e.m.f
B)A nickel-cadmium cell is an example of a primary cell
Insulation resistance of a motor fed from VFD shall be measured A)After disconnecting cables at VFD I/P side B)After disconnecting cables at VFD O/P side C)After disconnecting cables at motor side D)After ensuring all cables are connected
B)After disconnecting cables at VFD O/P side
Which of the following circuit breakers has the lowest operating voltage? A)SF6 circuit breaker B)Air break C)Minimum oil circuit breaker D)Air blast
B)Air break
An alternator is rated for 75 kW at 0.8 power factor. It means that A)The alternator has 4 poles B)An alternator can supply 75 kW at 0.8 power factor C)An alternator can supply power only to loads having power factor 0.8 only D)The peak efficiency of alternator occurs only at 75 kW load having 0.8 lagging power factor
B)An alternator can supply 75 kW at 0.8 power factor
What is the reactive power in AC operation? A)Real power × sinφ B)Apparent power × sinφ C)Real power × cosφ D)Apparent power × cosφ
B)Apparent power × sinφ
Which of the following relay is used to detect and protect internal fault of a transformer? A)Differential relay B)Bucholoz relay C)IDMT relay D)Directional relay
B)Bucholoz relay
The frame of an induction motor is usually made of A)Silicon steel B)Cast iron C)Aluminum D)Bronze
B)Cast iron
Consider two alternators are running in parallel now if the excitation of the one of the alternator is changed then it will A)Reduce speed B)Change power factor C)Change load demand D)Change frequency
B)Change power factor
In a thermal relay, a bi-metal strip consists of two metal strips having different A)Thermal conductivity B)Coefficient of expansion C)Specific heat D)All of the above
B)Coefficient of expansion
Inverters converts A)Dc power to dc power B)Dc power to ac power C)Ac power to ac power D)Ac power to dc power
B)Dc power to ac power
When 10 bulbs are operating in parallel in a AC circuit, if two additional bulb are operated in parallel with these bulbs, the effective resistance of circuit is A)Increases B)Decreases C)Remain same D)None of the above
B)Decreases
Which type of relays are used for instantaneous protection? A)Elect. Mech B)Differential C)Numerical D)Auxiliary
B)Differential
The acronym DCS stands for A)DeltaV Console Services B)Distributed Control System C)Direct Cascade Sequencing D)Differential Concentration Switch
B)Distributed Control System
The generator which gives dc supply to the rotor of an alternator is called A)Convertor B)Exciter C)Inverter D)Rectifier
B)Exciter
A SCADA system is open to many inputs and output, for that reason a SCADA system can not be configured for secure access A)TRUE B)FALSE C)Vary D)None of the above
B)FALSE
A SCADA system will only monitor and never make changes to the operations A)TRUE B)FALSE C)Vary D)None of the above
B)FALSE
Every SCADA system is unique to its environment, so there is no need to be consistent with colors, symbols and terminology A)TRUE B)FALSE C)Vary D)None of the above
B)FALSE
Motor mounting arrangement B5 denotes A)Foot Mounting B)Flange Mounting C)Both option 1 &2 are correct D)None of the options are correct
B)Flange Mounting
Which of the following terms specifies isolation of various compartments of switchgear from each other? A)Ingress Protection B)Form of separation C)Lockout-tagout D)None of these
B)Form of separation
Which of the following loss in a transformer is zero even at full load? A)Core loss B)Friction loss C)Eddy current loss D)Hysteresis loss
B)Friction loss
Which of the following generator protection leads to CO2 discharge? A)Loss of field B)Generator differential C)All of these D)None of these
B)Generator differential
Specific Gravity of a electrolyte in a single cell or a battery is always A)Equal to 1.0 B)Greater than 1.0 C)Less than 1.0 D)None of the above
B)Greater than 1.0
In a given transformer for given applied voltage, which of the following losses remain constant irrespective of load changes? A)Friction and windage losses B)Hysteresis and eddy current losses C)Cannot be determined D)Copper losses
B)Hysteresis and eddy current losses
Which of the following is the latest standard of communication for numeric relays? A)IEC-60850 B)IEC-61850 C)IEC-61580 D)IEC-60870
B)IEC-61850
What will happen if the transformers working in parallel are not connected with regard to polarity? A)The power factor of the two trans-formers will be different from the power factor of common load B)Incorrect polarity will result in dead short circuit C)The transformers will not share load in proportion to their kVA ratings D)Cannot be determined
B)Incorrect polarity will result in dead short circuit
EX e motors are A)Non sparking motors B)Increased safety motors C)Pressurized motors D)Flameproof motors
B)Increased safety motors
During charging the specific gravity of the electrolyte of a lead acid battery A)Decreases B)Increases C)Remain same D)None of the above
B)Increases
If the length of a cable is increased, its capacitance A)Decreases B)Increases C)Remain same D)None of the above
B)Increases
The direction of rotation of a D.C. series motor can be changed by A)Interchanging supply terminals B)Interchanging field terminals C)Either of (a) and (b) above D)None of the above
B)Interchanging field terminals
In OC test all the power supplied is utilized for A)Core losses B)Iron losses C)Windage losses D)Cannot be determined
B)Iron losses
An alternator is said to be over excited when it is operating at A)Leading Power Factor B)Lagging Power Factor C)Unity Power Factor D)None of the above
B)Lagging Power Factor
An alternator is said to be overexcited when it is operating at A)Unity power factor B)Leading power factor C)Lagging power factor D)Either lagging or leading power factor
B)Leading power factor
In cables the charging current A)Lags the voltage by 90° B)Leads the voltage by 90° C)Lags the voltage by 180° D)Leads the voltage by 180°
B)Leads the voltage by 90°
Why OC test is performed on LV side? A)Simple construction B)Less voltage is required and parameters can be transformed to HV side C)It'll not give losses if conducted on HV side D)HV side does not have connections for voltage
B)Less voltage is required and parameters can be transformed to HV side
The resistance between lightning protection system and earth should be: A)High B)Low C)Medium D)None of the above
B)Low
Which of the following ratings of circuit breaker will be highest among all? A)Breaking capacity B)Making capacity C)Continuous withstand D)None of these
B)Making capacity
Which of the following is used for providing protection against incoming surges? A)Silicon Oxide B)Metal Oxide Varistor C)Germanium Oxide D)None
B)Metal Oxide Varistor
Insulated cables are usually rated by their A)Operating voltage B)Operating voltage and highest operating temperature C)Current carrying capacity D)Cost
B)Operating voltage and highest operating temperature
A voltmeter must always connected in A)Series B)Parallel C)Series-parallel D)Any of the above
B)Parallel
In order to increase capacity of the battery, number of cells are connected in A)Series B)Parallel C)Both above D)None of the above
B)Parallel
Transformers operating in parallel mode of operation will share the load depending upon their A)Leakage reactance B)Per unit impedance C)Efficiencies D)Ratings
B)Per unit impedance
Two transformers operating in parallel will share the load depending upon their A)Leakage reactance B)Per unit impedance C)Efficiencies D)Ratings
B)Per unit impedance
The acronym PLC stands for: A)Pressure Load Control B)Programmable Logic Controller C)Pneumatic Logic Capstan D)PID Loop Controller
B)Programmable Logic Controller
In battery charger what type of circuit is used A)Inverter B)Rectifier C)Clamper D)Clipper
B)Rectifier
Metrosil is used for protection of A)Relays against over current B)Relays against over voltage C)Circuit breakers against over current D)Circuit breakers against over voltage
B)Relays against over voltage
During failure of prime mover in an alternator which relay is used to restore the working condition A)Buchholz Relay B)Reverse Power Relay C)Differential Relay D)Over speed relay
B)Reverse Power Relay
For high power applications _____ are used as static switches whereas for low power applications _____ are used A)Transistors, SCRs B)SCRs, transistors C)Diodes, transistors D)SCRs, diodes
B)SCRs, transistors
For the parallel operation of two single phase transformers it is necessary that they should have A)Same efficiency B)Same polarity C)Same kVA rating D)Same number of turns on the secondary side
B)Same polarity
If a D.C. motor is to be selected for conveyors, which rotor would be preferred? A)Shunt motor B)Series motor C)Cumulative compound motor D)Differentiate compound motor
B)Series motor
A fuse in a motor circuit provides protection against A)Overload B)Short-circuit and overload C)Open circuit, short-circuit and overload D)None of the above
B)Short-circuit and overload
For remote operation, circuit breaker must be equipped with A)Inverse shunt trip B)Shunt trip C)Time delay trip D)Both (1) and (3) above
B)Shunt trip
A circuit breaker is not closing mechanically, what could be the possible reason? A)Lockout relay operated B)Spring is not charged C)Closing coil faulty D)All of these
B)Spring is not charged
An over excited synchronous motor operating on no load condition is called as A)Synchronous generator B)Synchronous condenser C)Induction generator D)Induction motor
B)Synchronous condenser
What is "Opening time" of a circuit breaker? A)Time interval from the separation of contact to the extinction of the arc B)Time interval from the energization of the trip coil to the instant of contact separation C)Sum of the opening time interval and the arcing time interval D)Time interval from the energization of the solenoid to the instant of making contact for current establishment during closing of circuit breaker
B)Time interval from the energization of the trip coil to the instant of contact separation
Manual mode of the Bus-coupler breaker is generally used for A)To parallel both I/C breakers & B/C breaker in unsync mode B)To parallel both I/C breakers & B/C breaker in synch mode C)To switch OFF B/C manually when the synch is achieved between both I/C breakers D)All of these
B)To parallel both I/C breakers & B/C breaker in synch mode
In which of the protection system biased differential protection is preferred? A)Bus differential protection B)Transformer differential protection C)All of these D)None of these
B)Transformer differential protection
_____ is used for critical loads where temporary power failure can cause a great deal of inconvenience A)SMPS B)UPS C)MPS D)RCCB
B)UPS
Wound rotor induction motor is most appropriate for the applications requiring A)High starting torque B)Variable starting torque C)Fixed starting torque D)All of the mentioned
B)Variable starting torque
The thickness of insulation layer of a cable depends upon A)Reactive power B)Voltage C)Current carrying capacity D)All of the above
B)Voltage
The self-healthiness monitoring feature of a numeric relay is called A)Trip ckt. supervision B)Watchdog C)CT supervision D)VT supervision
B)Watchdog
In a three-phase induction motor, the number of poles in the rotor winding is always A)Equal to number of poles in stator B)Zero C)More than the number of poles in stator D)Less than the number of poles in stator
B)Zero
Which zone has explosive atmosphere less than 1000hrs/year? A)Zone 0 B)Zone1 C)Zone 2 D)Zone 3
B)Zone1
Low voltage circuit breakers have rated voltage of less than A)220V B)440V C)1000V D)6600V
C)1000V
Clearance required at the rear side of HV switchboard from wall as per OISD A)500mm B)1000mm C)1500mm D)2000mm
C)1500mm
If a feeder with circuit breaker and isolator is to be switched ON in loaded condition, which one of the following is correct switching ON sequence? A)1st Breaker, 2nd Isolator B)Both at the same time C)1st Isolator, 2nd Breaker D)None of these
C)1st Isolator, 2nd Breaker
A biased transformer differential protection requires minimum how many sets of 3-Ph CT inputs in a relay? A)3 B)1 C)2 D)6
C)2
For 50 Hz and 2 pole, the maximum speed of an alternator is A)6000 B)2500 C)3000 D)1500
C)3000
100 per cent stator E/F is based on A)Fundamental component of voltage B)2nd harmonic component of voltage C)3rd harmonic component of voltage D)5th harmonic component of voltage
C)3rd harmonic component of voltage
Which of the following correctly specifies short ckt. withstand of the 11KV switchboard? A)40KA B)40 KA @ 11KV C)40KA for 3 Sec D)None of these
C)40KA for 3 Sec
The maximum power in a synchronous machine is obtained when the load angle is A)0 degree B)120 degree C)90 degree D)45 degree
C)90 degree
The power consumed by circuit element is minimum when phase angle between current and voltage is A)0° B)45° C)90° D)180°
C)90°
The power developed by a synchronous motor will be maximum when the load angle is A)Zero B)45° C)90° D)120°
C)90°
The exciting field coil of an alternator is generally excited by A)A separate dc generator driver by some source B)A separate ac generator drive by some source C)A dc generator coupled directly to the armature shaft D)A battery
C)A dc generator coupled directly to the armature shaft
Which of the following medium is employed for extinction of arc in air circuit breaker? A)Water B)Oil C)Air D)SF6
C)Air
The capacity of a battery is expressed in term of A)Ampere B)Volt-hour C)Ampere-hour D)Volt-amp-hour
C)Ampere-hour
Which of the following protects a cable against mechanical injury? A)Bedding B)Sheath C)Armouring D)None of the above
C)Armouring
If the B/C breaker is not closing for paralleling of two Incomers, what could be the possible problem? A)A-I-M switch is kept in Manual mode B)Both I/C voltages are synchronized C)B/C breaker spring is not charged D)All of these
C)B/C breaker spring is not charged
FCBC Charger is used for A)Only float charging B)Only boost charging C)Both D)None
C)Both
Float charger does A)Feeding load B)Trickle charging battery C)Both D)None
C)Both
The frequency of voltage generated in an alternator depends on A)Number of poles B)Speed of alternator C)Both (a) and (b) D)Type of winding
C)Both (a) and (b)
Electrical Surges are be caused because of which one of the following? A)EHV Switching B)Lightning Strikes C)Both Lightning Strikes and EHV Switching D)None
C)Both Lightning Strikes and EHV Switching
Static UPS requires A)Only rectifier B)Only inverter C)Both inverter and rectifier D)None of the mentioned
C)Both inverter and rectifier
How many cores are used in a cable for the transmission of voltages upto 66 kV? A)A. Single core B)B. Two core C)C. Three core D)D. All of the above
C)C. Three core
Which of the following is the poorest conductor of electricity? A)Copper B)Aluminum C)Carbon D)Steel
C)Carbon
What is the lamination used for the stator? A)Cast iron B)Die cast aluminum alloy frame C)Cast iron or die cast aluminum alloy frame D)Cast iron and die cast aluminum alloy frame
C)Cast iron or die cast aluminum alloy frame
Open circuit test on transformers is conducted so as to get A)Hysteresis losses B)Copper losses C)Core losses D)Eddy current losses
C)Core losses
An induction motor when started on load, it does not accelerate up to full speed but runs at 1/7th of the rated speed. The motor is said to be A)Locking B)Plumbing C)Crawling D)Cogging
C)Crawling
If an induction motor with certain ratio of rotor to stator slots, runs at 1/7 of the normal speed, the phenomenon will be termed as A)Humming B)Hunting C)Crawling D)Cogging
C)Crawling
Fuse rating is expressed in terms of A)KVA B)Voltage C)Current D)VAR
C)Current
In power system, the function of relay is to A)Limit the current B)Control the fault current C)Detect the fault current D)Interrupt the circuit
C)Detect the fault current
Mechanical stress produced in the circuit A)Directly proportional to the square of the voltage B)Inversely proportional to the square of the voltage C)Directly proportional to the square of the currents D)Inversely proportional to the square of the current
C)Directly proportional to the square of the currents
Dissolved gas contents are need to be observed because A)Dissolved oxygen B)Dissolved gases from outside air C)Dissolved gases from arcs occurring in the transformer D)All dissolved gases
C)Dissolved gases from arcs occurring in the transformer
Which of the following statements is/are correct statements? A)EMF per turn in LV winding is more than EMF per turn in LV winding B)EMF per turn in LV winding is less than EMF per turn in LV winding C)EMF per turn in HV winding is equal to EMF per turn in LV winding D)Can't comment
C)EMF per turn in HV winding is equal to EMF per turn in LV winding
The main purpose of oil in a circuit breaker is A)Lubricate the contacts B)Insulate the contacts from switch body C)Extinguish the arc D)All of the above
C)Extinguish the arc
Alternator works on the principle of A)Self and mutual induction B)Self mutual induction C)Faraday's law of electromagnetic induction D)Mutual induction
C)Faraday's law of electromagnetic induction
Over speed protection of the generator is done by A)Differential relay B)Over current relay C)Governor D)Alarm
C)Governor
There is definite objection to use of which of the following medium for extinguishing the arc in case of a circuit breaker? A)Air B)SF6 C)H2O D)Vacuum
C)H2O
On which of the following effects of electric current a fuse operates? A)Photoelectric effect B)Electrostatic effect C)Heating effect D)Magnetic effect
C)Heating effect
Which of the following instrument is used to measure the specific gravity of electrolyte? A)Barometer B)Hygroscope C)Hydroscope D)Lactometer
C)Hydroscope
What is applicable IEC standard for Motors A)IEC-62271 B)IEC-60076 C)IEC-60034 D)IEC-60502
C)IEC-60034
Given two identical cables of same rating & same lot with 500m & 1000m length. Which is true for IR value for these cables? A)IR value will be high for 1000m length cable B)IR value will be same for both cables C)IR value will be high for 500m length cable D)None of these
C)IR value will be high for 500m length cable
What is applicable IS standard for Motors A)IS-12729 B)IS-2026 C)IS-325 D)IS-7098
C)IS-325
Flame proof switch gears are usually preferred A)On transmission lines of low voltage B)Substations C)In mines D)In high MVA capacity circuits
C)In mines
As per RTF guidelines, control supply of the MCC module fed motors shall be tapped from A)MCC Incomer B)Bus PT C)Incoming side of individual SFU D)Outgoing side of individual SFU
C)Incoming side of individual SFU
If the supply frequency to the transformer is increased, the iron loss will A)Not change B)Decrease C)Increase D)Cannot be determined
C)Increase
The term 'cogging' is associated with A)Three phase transformer B)Compound Generator C)Induction motor D)D.C series motor
C)Induction motor
Many digital control systems utilize Ethernet as a communications network, because A)No terminating resistors are necessary B)Speed is not affected by traffic C)It is a wireless network standard D)It is robust and inexpensive
C)It is a wireless network standard
In a three-phase half wave rectifier usually, the primary side of the transformer is delta connected because A)It has no neutral connection B)We can get greater output voltage C)It provides a path for the triplen harmonics D)It provides better temperature stability
C)It provides a path for the triplen harmonics
Which of the following battery is generally used in electric power station? A)Zinc carbon battery B)Nickel cadmium battery C)Lead acid battery D)Lithium battery
C)Lead acid battery
Which of these protections/functions cannot be provided by a relay with only CT inputs? A)Loss of load B)Load jam C)Load shedding D)All of these
C)Load shedding
The starting torque of a squirrel-cage induction motor is A)Full-load torque B)Slightly more than full-load torque C)Low D)Negligible
C)Low
Which of the following does not follow the criteria of station transformer? A)LV at 11 kV B)HV at 275-400 kV C)Low impedance D)On-load tap-changer required
C)Low impedance
The electrostatic stress in underground cables is A)Same at the conductor and the sheath B)Minimum at the conductor and maximum at the sheath C)Maximum at the conductor and minimum at the sheath D)Zero at the conductor as well as on the sheath
C)Maximum at the conductor and minimum at the sheath
In surge arresters MCOV corresponds to A)Maximum continuous Over Voltage B)Minimum continuous Over Voltage C)Maximum continuous Operating Voltage D)Minimum continuous Operating Voltage
C)Maximum continuous Operating Voltage
The voltage drop for which of the following types of brush can be expected to be least? A)Graphite brushes B)Carbon brushes C)Metal graphite brushes D)None of the options are correct
C)Metal graphite brushes
Which of the following is a motor protection relay? A)Micom P123 B)ABB REF 615 C)Micom P220 D)ABB REU 615
C)Micom P220
When the lead acid battery is fully charged condition, the appearance of its electrolyte is A)Bright B)Dull C)Milky D)Brown
C)Milky
Bypass mode for a VFD means A)All protections are bypassed B)All DCS interlocks are bypassed C)Motor runs at full speed without speed control D)All of these
C)Motor runs at full speed without speed control
Stored Transformer oil should be checked continuously for A)Impurities in the oil B)Oil levels C)Oil moisture content D)Oil reactions
C)Oil moisture content
When will a transformer have regulation closer to zero? A)On full-load B)On overload C)On leading power factor D)On zero power factor
C)On leading power factor
A synchronous motor can develop synchronous torque A)When under loaded B)While over-excited C)Only at synchronous speed D)Below or above synchronous speed
C)Only at synchronous speed
The structure of the IGBT is a A)P-N-P structure connected by a MOS gate B)N-N-P-P structure connected by a MOS gate C)P-N-P-N structure connected by a MOS gate D)N-P-N-P structure connected by a MOS gate
C)P-N-P-N structure connected by a MOS gate
Which of the following Transformer can have tap changer? A)Current transformer B)Potential transformer C)Power transformer D)Earthing transformer
C)Power transformer
EX p motors are A)Non sparking motors B)Increased safety motors C)Pressurized motors D)Flameproof motors
C)Pressurized motors
The inter-sheaths in the cables are used to A)Minimize the stress B)Avoid the requirement of good insulation C)Provide proper stress distribution D)None of the above
C)Provide proper stress distribution
AC ammeter and voltmeter generally determine the A)Maximum value B)Average value C)R.M.S. value D)Peak to peak value
C)R.M.S. value
The capacity of a lead acid cell does not depend on its A)Temperature B)Rate of discharge C)Rate of charge D)All of the above
C)Rate of charge
Which of the following are unit protection of transformers? A)O/C B)Stand by E/F C)Restricted E/F D)All of these
C)Restricted E/F
In three-phase squirrel-cage induction motors A)Rotor conductors are kept open B)Rotor conductor ends are short-circuited through slip rings C)Rotor conductors are short-circuited through end rings D)Rotor conductors are connected to insulation
C)Rotor conductors are short-circuited through end rings
Type of gas used in gas insulated switchgear as an insulating medium A)Freon B)Nitrogen C)SF6 D)Hydrogen
C)SF6
An induction Motor is A)Self-starting with high torque B)Self-starting with zero torque C)Self-starting with low torque D)Not self-starting
C)Self-starting with low torque
The exciter for a generator is a A)Shunt motor B)Series motor C)Shunt generator D)Compound motor
C)Shunt generator
For harmonic reduction by transformer connection, the output voltages from the two inverters must be A)Similar and in-phase with each other B)Dissimilar but in-phase with each other C)Similar but phase shifted from each other D)Dissimilar and phase shifted from each other
C)Similar but phase shifted from each other
The current from the stator of an alternator is taken out to the external load circuit through A)Slip rings B)Commutator segments C)Solid connections D)Carbon brushes
C)Solid connections
What is "Total break time" of a circuit breaker? A)Time interval from the separation of contact to the extinction of the arc B)Time interval from the energization of the trip coil to the instant of contact separation C)Sum of the opening time interval and the arcing time interval D)Time interval from the energization of the solenoid to the instant of making contact for current establishment during closing of circuit breaker
C)Sum of the opening time interval and the arcing time interval
The main purpose of using voltage dependent resistor in a circuit is to A)Limit the current B)Avoid overheating C)Suppress surge D)Provide variable voltage
C)Suppress surge
A motor which can conveniently be operated at lagging as well as leading power factors is the A)Squirrel cage induction motor B)Wound rotor induction motor C)Synchronous motor D)DC shunt motor
C)Synchronous motor
During short circuit test why iron losses are negligible? A)The current on secondary side is negligible B)The voltage on secondary side does not vary C)The voltage applied on primary side is low D)Full-load current is not supplied to the transformer
C)The voltage applied on primary side is low
Auto mode of the Bus-coupler breaker is generally used for A)To close the B/C breaker automatically if both I/C breakers have tripped B)To close the B/C breaker automatically if one of the I/C breakers have tripped on fault C)To close the B/C breaker automatically if one of the I/C breakers have tripped on no fault D)To trip the both Incomer breakers automatically if B/C breaker is switched ON
C)To close the B/C breaker automatically if one of the I/C breakers have tripped on no fault
Independent mode of the Bus-coupler breaker is generally used for A)To close the B/C breaker automatically independently of the position of any I/C breaker B)To parallel both I/C breakers & B/C breaker in Independent mode C)To switch on either I/C breaker or B/C breaker to charge dead bus D)All of these
C)To switch on either I/C breaker or B/C breaker to charge dead bus
Which of the following is used as a harmonic reduction technique in inverters? A)Amplitude modulation B)Cycloconverter control C)Transformer connection D)Series connection of two inverters
C)Transformer connection
The power factor of an alternator depends on A)Core Losses B)Speed of Motor C)Type of Load D)Armature losses
C)Type of Load
Which statement is true when motor is accelerated from standstill to full speed by a VFD? A)VFD increases O/P voltage gradually keeping frequency constant B)VFD increases O/P frequency gradually keeping voltage constant C)VFD increases both O/P voltage & frequency together gradually D)VFD does not change O/P voltage or frequency
C)VFD increases both O/P voltage & frequency together gradually
The ANSI code 51V corresponds to A)Differential B)Loss of field C)Voltage dependent O/C D)Over frequency
C)Voltage dependent O/C
Line PT measurements: R-Ph 232V, Y-Ph 0V, B-Ph 233V. Bus PT measurements for same section: R-Ph 232V, Y-Ph 234V, B-Ph 233V. What could be the problem? A)Y-Phase phase open at transformer end B)Y-Phase pole of Breaker open C)Y-Phase fuse of Line PT secondary blown D)Any of these
C)Y-Phase fuse of Line PT secondary blown
The negative pole of a dry cell is made of A)Carbon B)Copper C)Zinc D)Mercury
C)Zinc
EX nA are designed to use in A)Zone 0 B)Zone1 C)Zone 2 D)Zone 3
C)Zone 2
Which zone has explosive atmosphere less than 10hrs/year? A)Zone 0 B)Zone1 C)Zone 2 D)Zone 3
C)Zone 2
The forward voltage drop across a diode is about A)2.5V B)3V C)10V D)0.7V
D)0.7V
A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor e.m.f. will be A)200 Hz B)50 Hz C)0.2 Hz D)2 Hz
D)2 Hz
The zone of protection (surrounding area that a lightning protection system protects) is approximately ____ times the height of building protected A)4 times B)3 times C)5 times D)2 times
D)2 times
EX d are designed to use in A)Zone 0 B)Zone1 C)Zone 2 D)2&3
D)2&3
EX e are designed to use in A)Zone 0 B)Zone1 C)Zone 2 D)2&3
D)2&3
EX p are designed to use in A)Zone 0 B)Zone1 C)Zone 2 D)2&3
D)2&3
The full-load copper loss of a transformer is 1600 W. At half-load, the copper loss will be A)6400 W B)1600 W C)800 W D)400 W
D)400 W
Distribution transformers are generally designed for maximum efficiency around A)90% load B)Zero load C)25% load D)50% load
D)50% load
A battery consists of A)A cell B)A circuit C)A generator D)A number of cells
D)A number of cells
An efficient and well-designed protective relay should have A)Good selectivity and reliability B)Economy and simplicity C)High speed and selectivity D)All of the above
D)All of the above
In large synchronous generator or alternator, the protection provide for external fault is A)Inter-turn fault protection B)Sensitive earth Fault protection C)Biased differential protection D)All of the above
D)All of the above
Nickel-Cadmium batteries are preferred more than Lead-Acid batteries in many applications because——- A)Can be easily charged and discharged B)Discharge rate is higher C)Delivers large amount of power D)All of the above
D)All of the above
The 3-phase unbalanced stator current in an alternator or synchronous machine cause A)Heating of rotor B)Vibration C)Double frequency current in the rotor D)All of the above
D)All of the above
The function of damper winding in an alternator is A)Damp oscillation B)Provide stability C)Eliminate Haunting D)All of the above
D)All of the above
The insulating material for a cable should have A)Low cost B)High dielectric strength C)High mechanical strength D)All of the above
D)All of the above
The insulating material used in cable should have A)Low permittivity B)High resistivity C)High dielectric strength D)All of the above
D)All of the above
The method of reducing the harmonic in an alternator are A)Well distributed winding B)Using short pitch winding C)Slots are skewed D)All of the above
D)All of the above
A SCADA system will include A)Signal hardware (input and output)controllers B)Networks C)User interface (HMI) D)All of the mentioned
D)All of the mentioned
Before planning an alarm system within the SCADA one should consider A)What conditions triggers the alarm? B)How operators will be notified of those alarms? C)What actions will occur in response to those alarms? D)All of the mentioned
D)All of the mentioned
Mechanically air gaps in induction motor are kept very low to avoid A)Lower power factor B)Lagging nature C)Magnetizing current D)All of the mentioned
D)All of the mentioned
Relatively a squirrel-cage induction motor is advantageous over wound rotor type induction motor of identical rating due to A)Less conductor material used B)Lower leakage flux C)Ruggedness D)All of the mentioned
D)All of the mentioned
Usually _____ batteries are used in the UPS systems A)Ni-Cd B)Li-ion C)Lead acid D)All of the mentioned
D)All of the mentioned
When planning a SCADA system you should: A)Collect data B)Have an understanding of the process C)Design a database D)All of the mentioned
D)All of the mentioned
A circuit breaker is not closing electrically, what could be the possible reason? A)Lockout relay operated B)Spring is not charged C)Closing coil faulty D)All of these
D)All of these
In generator Class A tripping corresponds to A)Generator trip B)Turbine trip C)Field breaker trip D)All of these
D)All of these
The EMF generated in alternator depends on A)Frequency B)Flux per pole C)Coil span factor D)All of these
D)All of these
When a generator is operating by itself supplying the system load then real and reactive power supplied by the generator depends upon A)Prime mover RPM B)Type of Insulation C)Inter-coil Inductance D)Amount demanded by load
D)Amount demanded by load
The number of brushes in a commutator depends on A)Speed of armature B)Type of winding C)Voltage D)Amount of current to be collected
D)Amount of current to be collected
In a circuit breaker if the insulation resistance between phase terminal and earthed frame is less than the specified limit, the probable cause could be A)Moisture B)Dirty insulation surface C)Carbon or copper particles sticking to the internal surface D)Any of the above
D)Any of the above
If one of the three phases of the induction motor fails due to fault. The motor will A)Stop and do permanent damage if it was running overloaded B)Continue running but will draw more current if it was operating at rated load C)Will not be affect the operation if light loaded D)Any of the mentioned
D)Any of the mentioned
Line PT measurements: R-Ph 232V, Y-Ph 234V, B-Ph 233V. Bus PT measurements for same section-Ph 232V, Y-Ph 0V, B-Ph 233V. What could be the problem? A)Y-Phase phase open at transformer end B)Y-Phase pole of Breaker open C)Y-Phase fuse of Bus PT secondary blown D)Both 2 & 3
D)Both 2 & 3
Insulated conductor is called as A)Wire B)Conductor C)Pipe D)Cable
D)Cable
The material for commutator brushes is generally A)Mica B)Copper C)Cast iron D)Carbon
D)Carbon
What type of coils are used for winding the single phase induction motor generally? A)Rectangular coils B)Square coils C)Cruciform coils D)Circular coils
D)Circular coils
When will be the efficiency of a transformer maximum? A)Copper losses = hysteresis losses B)Hysteresis losses = eddy current losses C)Eddy current losses = copper losses D)Copper losses = iron losses
D)Copper losses = iron losses
In a cable the voltage stress is maximum at A)Sheath B)Insulator C)Surface of the conductor D)Core of the conductor
D)Core of the conductor
IDMT relays are used to protect the power transformers against A)External short-circuits B)Overloads C)Internal short-circuits D)External short-circuits and overloads
D)External short-circuits and overloads
The fault clearing time of a circuit breaker is usually A)Few minutes B)Few seconds C)One second D)Few cycles of supply voltage
D)Few cycles of supply voltage
EX d motors are A)Non sparking motors B)Increased safety motors C)Pressurized motors D)Flameproof motors
D)Flameproof motors
Which is the least expensive protection in LV circuits? A)Isolator B)MOCB C)ACB D)Fuse
D)Fuse
The 'crawling" in an induction motor is caused by A)High loads B)Low voltage supply C)Improper design of machine D)Harmonics developed in the motor
D)Harmonics developed in the motor
A short circuit is identified by A)No current flow B)Voltage drop C)Voltage rise D)Heavy current flow
D)Heavy current flow
What is applicable IEC standard for XLPE Cables? A)IEC-62271 B)IEC-60076 C)IEC-60034 D)IEC-60502
D)IEC-60502
What is applicable IS standard for XLPE Cables? A)IS-12729 B)IS-2026 C)IS-325 D)IS-7098
D)IS-7098
Sulphation in a lead acid battery occurs due to A)Trickle charging B)Heavy charging C)Overcharging D)Incomplete charging
D)Incomplete charging
The term 'cogging' is associated with A)Three phase transformers B)Compound generators C)D.C. series motors D)Induction motors
D)Induction motors
Differential relay are used to protect the equipment against A)External faults B)Over current C)Reverse current D)Internal faults
D)Internal faults
For two transformers connected in parallel, not having unequal percentage impedances, which statement is correct? A)Short-circuiting of the secondaries B)Power factor of one of the transformers is leading while that of the other lagging C)Transformers having higher copper losses will have negligible core losses D)Loading of the transformers not in proportion to their kVA ratings
D)Loading of the transformers not in proportion to their kVA ratings
A synchronous motor is running on a load with normal excitation. Now if the load on the motor is increased A)Power factor as well as armature current will decrease B)Power factor as well as armature current will increase C)Power factor will increase but armature current will decrease D)Power factor will decrease and armature current will increase
D)Power factor will decrease and armature current will increase
During open circuit test (OC) of a transformer A)Primary is supplied rated kVA B)Primary is supplied full-load current C)Primary is supplied current at reduced voltage D)Primary is supplied rated voltage
D)Primary is supplied rated voltage
When immediate tripping of the transformer from the main circuit is required? A)Local overheating B)Short-circuited core laminations C)Core-bolt insulation failure D)Puncture of bushings
D)Puncture of bushings
In squirrel cage induction motors, the rotor slots are usually given slight skew in order to A)Reduce windage losses B)Reduce eddy currents C)Reduce accumulation of dirt and dust D)Reduce magnetic hum
D)Reduce magnetic hum
The great advantage of the double squirrel-cage induction motor over single cage rotor is that its A)Efficiency is higher B)Power factor is higher C)Slip is larger D)Starting current is lower
D)Starting current is lower
A switchgear is device used for A)Interrupting an electrical circuit B)Switching an electrical circuit C)Switching and controlling an electrical circuit D)Switching, controlling and protecting the electrical circuit and equipment
D)Switching, controlling and protecting the electrical circuit and equipment
The contact resistance is least affected by A)The mechanical force applied B)The shape of the contact faces C)The amount of surface contamination D)The ambient temperature
D)The ambient temperature
In a PLC, the scan time refers to the amount of time in which A)The technician enters the program B)Timers and counters are indexed by C)One "rung" of ladder logic takes to complete D)The entire program takes to execute
D)The entire program takes to execute
On which of the following degree of mechanical vibrations produced by the laminations of a transformer depends? A)Tightness of clamping B)Gauge of laminations C)Size of laminations D)Tightness of clamping, gauge and size of laminations
D)Tightness of clamping, gauge and size of laminations
Recommended minimum IR (insulation resistance) value for an LT system is A)1 MΩ B)0.5MΩ C)0.8MΩ D)2MΩ
A)1 MΩ
Which of the following acts as a protection against high voltage surges due to lightning and switching? A)Horn gaps B)Thermal overload relays C)Breather D)Conservato
A)Horn gaps
In power outage, FCBC is in A)Float mode B)Boost mode C)Both D)None
B)Boost mode
Which battery charger is normally used? A)Float B)Boost C)Fcbc D)None
C)Fcbc
The insulating material used between the commutator segments is normally A)Graphite B)Paper C)Mica D)Insulating varnish
C)Mica
Numeric relay based transformer differential protection schemes are of typically of which type? A)High Impedance B)IDMT C)Definite Time D)Low Impedance
D)Low Impedance
In an alternator, when the load increases due to armature reaction, the terminal voltage A)Rises B)Drops C)Remains unchanged D)May drop or rise
D)May drop or rise
Localization of cable faults done by A)Short circuit tests B)Murray loop tests C)Varley loop tests D)Murray and Varley loop test
D)Murray and Varley loop test
An OR function implemented in ladder logic uses: A)Normally-closed contacts in series B)Normally-open contacts in series C)A single normally-closed contact D)Normally-open contacts in parallel
D)Normally-open contacts in parallel
A synchronous motor can be used as a synchronous capacitor when it is A)Under-loaded B)Over-loaded C)Under-excited D)Over-excited
D)Over-excited
Distance Protection Scheme is used for the protection of A)Motor B)Transformer C)Alternator D)Overhead line
D)Overhead line
What is "Arcing time" of a circuit breaker? A)Time interval from the energization of the trip coil to the instant of contact separation B)Sum of the opening time interval and the arcing time interval C)Time interval from the energization of the solenoid to the instant of making contact for current establishment during closing of circuit breaker D)Time interval from the separation of contact to the extinction of the arc
D)Time interval from the separation of contact to the extinction of the arc
Armour of a single core cable A)To be earthed at both ends of cable B)To be earthed at sending end of the cable C)To be earthed at receiving end of the cable D)To be earthed at any one end of the cable
D)To be earthed at any one end of the cable
Station transformers are generally used for A)Providing generator voltage to transmission B)Providing power to load from transmission C)Isolating DC D)To supply power section auxiliary
D)To supply power section auxiliary
For a transformer given, operating at constant load current, maximum efficiency will occur at A)0.8 leading power factor B)0.8 lagging power factor C)Zero power factor D)Unity power factor
D)Unity power factor
The drive motor used in a mixer-grinder is a A)DC motor B)Induction motor C)Synchronous motor D)Universal motor
D)Universal motor
Two alternators are running in parallel if the excitation of the one of the alternator is changed then A)Active component will change B)Vibration will occur in an alternator C)Alternator will run as the motor D)Wattless component will change
D)Wattless component will change
The difference between online and offline PLC programming is A)Whether the PLC is running or stopped B)Whether the programming PC has internet connectivity C)The type of programming cable used D)Where the edited program resides
D)Where the edited program resides
The percentage slip in case of a synchronous motor is A)0.01 B)1 C)0.005 D)Zero
D)Zero