OBJECTIVE
Q- The main purpose of the commutator & brushes on a DC generator is to
a) transfer generated DC voltage from the armature to the line
b) convert the alternating voltage generated withtin the armature to a direct voltage
c) provide a sliding contact method to excite the field
d) reduece sparking between the armature and the carbon brushes
Answer-B
Q- In diesel generator, increasing the fuel due to drop in load , which will --------------------save machine from damage
A.Limiting load switch
B.Limiting shredded switch
C.Limiting sensor
D.Limiting
Answer-A
Q- Which of the following statements represents an application of a silicon controlled rectifier?
A. To provide DC power for a main propulsion motor.
B. For use as a voltage reference diode.
C. For sensing flame in an automated burner.
D. To eliminate power supply hum.
Answer-A
Q- AC circuits possess characteristics of resistance, inductance, and capacitance.The capacitive reactance of acircuit is expressed in
A.ohms
B.mhos
C.henrys
D.farads
Answer-A
Q- A low voltage protection circuit is used in electric motor starting equipment to
A.Trip circuit contractor when the motor overspeed due to low voltage
B. Trip circuit contractor when the motor develops short circuit due to low voltage
C.Allows the motor to restart automatically on restoration of voltage without manual resetting
D.prevent motor from restarting automatically
Answer-D
Q- If an intrinsic semiconductor is doped with a very small amount of boron then the extrinsic semiconductor set formed, the no. of electrons and holes will
A.both Dec.
B.increase and decrease
C.Both increase
D.Decrease and increase
Answer-D
Q- In what range of voltages is the transistor in the linear region of its operation?
A. 0 < VCE < 0.7 V
B. 0.7 < VCE < 1.4 V
C. 0.7 < VCE < VCE(max)
D. 0 < VCE < VCE(max)
Answer-C
Q- The greatest detrimental effect on idle electrical equipment, such as cargo pump motors,is the
A. Loss of residualmagnetism.
B. Absorption of moisture in the insulation.
C. Insulation varnish flaking.
D. Dirt collecting on the windings.
Answer-B
Q- Arrange the following in Increasing Order of their Doping Strength.
A. Collector, Emitter, Base
B. Base, Emitter, Collector
C. Emitter, Base, Collector
D. Emitter, Collector, Collector Base, Collector, Base
Q- In an N-Type Semiconductor, the minority current Carriers are ___________.
Answer-HOLES
Q- The winding resistance of a coil can be increased by _______ the number of turns or using a ______ wire.
A. increasing, thicker
B. decreasing, thicker
C. increasing, thinner
D. decreasing, thinner
Multiple Choice Question
Q- A poly-phase motor driving an engine room pump fails to start. When trying to identify the cause of failure, which of the following steps are applicable?
A. Visually examine motor for open circuit faults.
B. Visually examine starter for open circuit faults.
C. Reverse the direction of electrical supply to check if it works.
D. Perform the infinite resistance test
Answer-A,B and D
Q- The induced voltage across a stationary conductor in a steady magnetic field is zero.
True
False
Answer-True
Multiple Choice Question
Q- When paralleling an AC generator with live bus bars, which of the following precautions are applicable?
A.Generator frequency should be slightly lower than bus bar frequency
B.Generator frequency should be slightly higher than bus bar frequency
C.Generator voltage should be in phase with bus bar voltage
D.Generator voltage should be out of phase with bus bar voltage
Answer-B and C
Multiple Choice Question
Q- The current in a semiconductor is produced by:
A. Electrons
B. Neutrons
C. Protons
D. Holes
Answer-A and D
Q- Open loop function of a sys has zero with positive real value is called _____________ phase function.
Answer-Non Minimum
Q- The direction of magnetic flux changes when the direction of current is reversed.
True
False
Answer-True
Q- Which of the listed devices may be installed on a large turbo-electric alternating current propulsion generator?
A. Temperature detector coils inserted in the stator slots for measuring stator temperature.
B. A CO2 fire extinguishing system.
C. Electric space heaters to prevent condensation of moisture.
D. All of the above
Answer-D
Q- To check the setting of the overspeed trip on a diesel powered generator, you would use a
A. tachometer
B. torsion meter
C. dynamometer
D. pony brake
Answer-A
1. Which of the following statements is true concerning a poly-phase synchronous propulsion motor?
A. The motor is started as an induction motor.
B. Resistance is gradually added to the rotor circuit.
C. The starting current is held below the rated current.
D. The field winding is energized for starting purposes only.
Answer-
2. When reading electrical motor controller diagrams, it helps to know that ____________.
A. current paths in the control circuit are drawn as heavy lines and in the power circuit as lighter lines
B. current paths in the power circuit are drawn as heavy lines and in control circuit as lighter lines
C. circuits subject to 500 volts or greater are drawn as heavy lines and below 500 volts as lighter lines
D. circuits subject to 500 volts or greater are drawn as light lines and below 500 volts as heavy
Answer-
3. Alternating current circuits develop resistance, inductance and capacitance. The inductance of a coil is expressed in _____________.
A. ohms
B. mhos
C. henrys
D. farads
Answer-
4. Large cable sizes are formed as individual conductors that may be comprised of several smaller strands to __________.
A. obtain the flexibility required for easy handling
B. reduce the overall weight of the wire run
C. reduce the number of supports needed for a horizontal overhead run
D. all of the above
Answer-
5. Which of the following is having Di-Electric Constant 80?
A. Air
B. water
C. Mica
D. Caster oil
Answer-
6. Where a thermal-acting breaker is required to be used in an area of unusually high, low, or constantly fluctuating temperatures, an ambient compensating element must be used. This element consists of a ______________.
A. cylindrical spring on the contact arm
B. conical spring on the contact arm
C. second bimetal element
D. second electromagnet
Answer-
7. Which of the following precautions should you take when securing propulsion generators and motors for an extended period of time?
A. Disconnect the brush pigtails from their contacts and circulate air through the units.
B. Disconnect the brush pigtails from their contacts and discharge carbon dioxide into the units to keep them dry.
C. Lift the brushes from commutator collector rings and use the built-in heater to prevent moisture accumulation.
D. Lift the brushes from commutator collector rings and circulate cool dry air through the units.
Answer-
8. The direction of magnetic flux changes when the direction of current is reversed.
True
False
Answer-
9. In a Transistor
A. PNP and NPN are two basic types
B. Emitter,Collector and Base are the basic Elements.
C. Collector separates Base and Emitter
D. Emitter separates Base and Collector
Answer-
Q- In a P-Type Semiconductor, the majority current Carriers are ___holes________.
10. In a Control Loop System, having Zero(0) Positive Real Values are called______ PHASE CURRENT ______.
11. If a Motor is not rotating in the E/R, you will carry out the following Checks (multiple choice, 3 Questions of same type but Options were different )
A. Check for the isolation
B. Rotate the Coupling with your hand
C. Check for the Circuit breaker
D. Remove the fuses
E Look for the Overload Trip
F. Visually Inspect the motor terminals
G. Visually Inspect the Starter Terminals
H. Carry out Infinite Resistance Test
Answer-
14. Calculate the Velocity of the conductor (up to 0 decimal places), if terminal voltage is 2.2 V/m and the magnetic field strength is 0.2 T. .
15. Calculate the frequency of the motor ( up to 0 decimal places),, if the speed if 4800 Rpm and number of Poles is 2. N=120f/P => 4800*2/120 =. f = 80
16. If the resistance of any coil is 120 Ohm. Calculate the Resistance (up to 0 decimal places), when its Length is increased by 20% and its Diameter is increased by 50%. R= specific resistance * length / Area
Answer 96 R1/R2=L1/L2 * A2/A1 = 120/X= 100/120 * 150/100 =96
17. What is the power in a Resistor in Milli Watts (up to 0 decimal places), having Resistance of 12 Ohm having a Potential Difference of 3 V. P=V^2 / R multiply to get milli watts value
18. Resistance of a wire is increased if the Length is__Increased__ and Area is __decreased___. refer R= specific resistance * length / Area
Q- the apparent power in a purely inductive circuit is known as
1. true power
2. lead power
3 inductive power
4. reactive power
Answer-4
19. Arrange the following in Increasing Order of their Doping Strength. Answer is-Base, collector, emitter
A. Collector, Emitter, Base
B. Base, Emitter, Collector
C. Emitter, Base, Collector
D. Emitter, Collector, Collector Base, Collector, Base
Answer-
20. Which of the listed precautions should be taken when cleaning the internals of a motor with compressed air?
A. Open the machine on both ends so as to allow the air and dust to escape.
B. Be certain that the circuit breaker is opened and tagged on the feeder panel.
C. Be certain that the air is clean and as dry as possible.
D. All of the above
Answer-
Q- In three phase electrical equipment, the immediate action in the event of fuse blowing in one of the phases would be
a. to replace with a fuse of correct rating
b. to replace fuses on all three phases
c. to try to repair the fuse
d. to investigate the fault that led to blowing the fuse
Answer-D
1. Which of the following statements is true concerning a poly-phase synchronous propulsion motor?
A. The motor is started as an induction motor.
B. Resistance is gradually added to the rotor circuit.
C. The starting current is held below the rated current.
D. The field winding is energized for starting purposes only.
Answer-
2. When reading electrical motor controller diagrams, it helps to know that ____________.
A. current paths in the control circuit are drawn as heavy lines and in the power circuit as lighter lines
B. current paths in the power circuit are drawn as heavy lines and in control circuit as lighter lines
C. circuits subject to 500 volts or greater are drawn as heavy lines and below 500 volts as lighter lines
D. circuits subject to 500 volts or greater are drawn as light lines and below 500 volts as heavy
Answer-
3. Alternating current circuits develop resistance, inductance and capacitance. The inductance of a coil is expressed in _____________.
A. ohms
B. mhos
C. henrys
D. farads
Answer-
4. Large cable sizes are formed as individual conductors that may be comprised of several smaller strands to __________.
A. obtain the flexibility required for easy handling
B. reduce the overall weight of the wire run
C. reduce the number of supports needed for a horizontal overhead run
D. all of the above
Answer-
5. Which of the following is having Di-Electric Constant 80?
A. Air
B. water
C. Mica
D. Caster oil
Answer-
6. Where a thermal-acting breaker is required to be used in an area of unusually high, low, or constantly fluctuating temperatures, an ambient compensating element must be used. This element consists of a ______________.
A. cylindrical spring on the contact arm
B. conical spring on the contact arm
C. second bimetal element
D. second electromagnet
Answer-
7. Which of the following precautions should you take when securing propulsion generators and motors for an extended period of time?
A. Disconnect the brush pigtails from their contacts and circulate air through the units.
B. Disconnect the brush pigtails from their contacts and discharge carbon dioxide into the units to keep them dry.
C. Lift the brushes from commutator collector rings and use the built-in heater to prevent moisture accumulation.
D. Lift the brushes from commutator collector rings and circulate cool dry air through the units.
Answer-
8. The direction of magnetic flux changes when the direction of current is reversed.
True
False
Answer-
9. In a Transistor
A. PNP and NPN are two basic types
B. Emitter,Collector and Base are the basic Elements.
C. Collector separates Base and Emitter
D. Emitter separates Base and Collector
Answer-
9. 9. In a P-Type Semiconductor, the majority current Carriers are ______holes_____.
10. In a Control Loop System, having Zero(0) Positive Real Values are called____________. PHASE CURRENT
11. If a Motor is not rotating in the E/R, you will carry out the following Checks (multiple choice, 3 Questions of same type but Options were different )
A. Check for the isolation
B. Rotate the Coupling with your hand
C. Check for the Circuit breaker
D. Remove the fuses
E Look for the Overload Trip
F. Visually Inspect the motor terminals
G. Visually Inspect the Starter Terminals
H. Carry out Infinite Resistance Test
Answer-
14. Calculate the Velocity of the conductor (up to 0 decimal places), if terminal voltage is 2.2 V/m and the magnetic field strength is 0.2 T. 2.2/0.2 = 110M/S
15. Calculate the frequency of the motor ( up to 0 decimal places),, if the speed if 4800 Rpm and number of Poles is 2. .....ans. 80hz formula is N= 120f/p
16. If the resistance of any coil is 120 Ohm. Calculate the Resistance (up to 0 decimal places), when its Length is increased by 20% and its Diameter is increased by 50%. 120 ohm...resistence will remain the same
17. What is the power in a Resistor in Milli Watts (up to 0 decimal places), having Resistance of 12 Ohm having a Potential Difference of 3 V. Ans. 750 mw. Or 75w answer is not sure.. formula is p=VIcos phi
18. Resistance of a wire is increased if the Length is _____increased_____ and Area is ____decreased________.
19. Arrange the following in Increasing Order of their Doping Strength.
A. Collector, Emitter, Base
B. Base, Emitter, Collector
C. Emitter, Base, Collector
D. Emitter, Collector, Collector Base, Collector, Base
Answer-
20. Which of the listed precautions should be taken when cleaning the internals of a motor with compressed air?
A. Open the machine on both ends so as to allow the air and dust to escape.
B. Be certain that the circuit breaker is opened and tagged on the feeder panel.
C. Be certain that the air is clean and as dry as possible.
D. All of the above
Answer-
2. What is the maximum allowable primary current of a 2 KVA step-down transformer with a four to one turns ratio if the primary is connected across a 440 volt line? P=vi.-? we get I1 , then N1/N2=I2/I1
A 1.1 amps
B 4.5 amps
C 18.1 amps
D 27.7 amps
Answer-
1. Time delayed or delayed action-type fuses are designed to _____________.
(A) prevent grounds in branch circuits
(B) prevent opens in motor circuits
(C) permit momentary overloads without melting
(D) guard lighting and electronic circuits Briefly justify your answer
Answer-
2. Silicon diodes designed for a specific reverse breakdown voltage, become useful as an electronic power supply voltage regulator, called _____________.
(A) tunnel diodes
(B) hot-carrier diodes
(C) compensating diodes
(D) Zener diodes Briefly justify your answer
Answer-
3. Which of the following statements best describes the material known as varnished cambric?
(A) Felted asbestos sealed with varnish.
(B) Cotton cloth coated with insulating varnish.
(C) Rubber insulation coated with a layer of tin.
(D) Paper impregnated with mineral oil, specially wrapped with nonmetallic tape, and coated with varnish. Briefly justify your answer
Answer-
4. A synchronous motor maintains synchronism with the rotating field because _____________.
(A) field strength varies directly with rotors lIp
(B) DC current applied to the rotor coils causes the rotor magnets to lock in with the rotating flux of the stator
(C) the stator poles are dragged around due to the flux created by the excitation current
(D) the stator flux rotates in the opposite direction Briefly justify your answer
Answer-
6. The part of a fuse that melts and opens the circuit is made of _____________.
(A) Copper and antimony
(B) Steel and Babbitt
(C) Aluminum or beryllium alloy
(D) Zinc or an alloy of tin and lead
Answer-
Briefly justify your answer
1 the appereant powerin inductive circuit
a truepower
b lead
c inductive
d reactive
Answer-
2 delayed action of fuse is meet ffrequency
a lightining
b motor
c radar
d none of above
3 the inductive loop of rotor simple two pole single phase generator rotates 400rps calculate frequency of induceed out put voltage N=120f/P
4 poly phase motor fails what cause for failure what should be check
a isolate motor
b remove fuse
c post cautions signs
d ensure starter motor terminals live
Answer-
5 instrinsic semi conductor is dooped with small amount of boron in the extrinsic semi conductor formed the no of electron hole will precauton to take cleaning the motor with compressed air......... uscg refer
6 when reading electrical motor controller dealing its helps data logger for refregeration systems ... dnt know potions
8 break down diode____zener diode ___ and___avalanche diode____(reverse biasing)
9 basic measuring of inductance
a columb
b ohm
c faraday
d henry
10 open loop function system having one zero positiva real valueof __________ phase function
11 semmi conductor failed to over curent reason___low breakdown voltage___ and_________
12 sum 700w 36dayslike tht question 700xdays 36 x one day 24/ 1000
13 three resistor 40,50,60 connected in series input 30v calculate voltage drop across 60 resistor
If a Motor is not rotating in the E/R, you will carry out the following Checks (multiple choice, 3 Questions of same type but Options were different)
A. Check for the isolation
B. Rotate the Coupling with your hand
C. Check for the Circuit breaker
D. Remove the fuses
E Look for the Overload Trip
F. Visually inspect the motor terminals
G. Visually Inspect the Starter Terminals
H. Carry out Infinite Resistance Test
Answer-All Checks that was Given Above
ACB trips at what condition
1 reverse current
2 short circuit
3overload
4 low voltage fault
Answer-2
For leading power factor circuits, which of the following can be used?
A. Shunt Capacitors only
B. Shunt Reactors only
C. Either Shunt Capacitors or Shunt Reactors
D. Neither Shunt Capacitors nor Shunt Reactors
Answer-B
Incandescent lamps are classified according to
-shape of bulb and type of service
-size and style of base
-operating voltage and wattage
-all of the above
Answer-D
Fuses placed in series with a thermal trip = - type circuit breaker are used for
A.Time-delay protection
B.Short-circuit protection
C.Short duration surge protection
D.Sustained overload protection
Answer-B
Why is a capacitor used in single phase motors, fluorescent tube lights and electronic circuits.*
A. To provide a 90 deg phase shift to the incoming supply necessary for starting the motor.
B. To provide boost voltage for starting, power factor correction and to minimize
radio interference.
C. For stabilizing voltage, filtration and coupling
Answer-A
What type of of rotor is used in split phase motor?
A.drum
B.salient pole
C.squirrel cage
D.wound rotor
Answer-C
In a intrinic semi-conductor doped with very small amount of boron what will effect occur on holes and electrones
A. increasing holes
B.increasing electrones
C.respectively increasing decreasing
D.respectively decreasing increasing
Answer-C
In three phase electrical equipment, the immediate action in the event of fuse blowing in one of the phases would be
a. to replace with a fuse of correct rating
b. to replace fuses on all three phases
c. to try to repair the fuse
d. to investigate the fault that led to blowing the fuse
Answer-D
THE POTENTIAL BARRIER OF A SEMICONDUCTOR IS EXCEEDED- THEN FORWARD CURRENT WILL __________
INCREASE OR DECREASE
Answer-Increase
Fwd bias voltage of semiconductor diode
a)<.1v
b) <0.4v
c)>0.7v
d)>1.4 v
Answer-C
Forward bias voltage of semi conductor diode????
1. <.1v
2.<.4v
3.< .7v
4.<.1.4 v
Answer-D
Motor stator winding badly contaminated by dirt, oil and grease should be cleaned by:
A. High pressure compressed air
B. Suction or vacuum cleaning
C. Brushing, spraying or immersion in an approved cleaning solvent
D. Immersion in fresh water followed by drying
Answer-C
The most common source of excitation for synchronous motors is a/an _____________.
(A) low voltage battery
(B) motor attenuator set
(C) DC exciter generator
(D) AC supply
Answer-C
In the illustration, if the device in figure "A" has a step-up ratio of 10 to 1, what voltage should be measured at the secondary shortly after the primary of the device is connected to 110 volts DC?
0 volts
110 volts
11 volts
1100 volts
Answer-0 Volts (Because he is Talking About DC These type of Question is Just to Confuse You)
To prevent the race of a dc series motor what arrangement should make?
A.allways start at heavy load.
B.use a strong series-weak shunt compound dc motor.
C.use a weak series- strong shunt compound dc motor.
D. All of the above.
Answer-C
The armataure resistance of a 200 V d.c. machine has 0.5 ohm. If the full load armature current is 50 A, what will be the induced e.m.f. when, the machine acts as
(i) generator (ii) motor will be
(a) 230 V, 170 V
(b) 210 v, 190 v,
(c) 225 V, 175 C
(d)202.5 V, 197.5 V
Answer-C Because(e=v+ir gen, e=v-ir motor)
the winding resistance of a coil can be increased by___________the number of turns or using a _________wire.
Answer-Increase and Thinner Wire
A FUSE WILL BLOW FOR ALL OF THE LISTED REASON EXCEPT
1. excessive vibration
2. extremely hot surrounding
3. loose fuse clips
4. low contact resistance with the fuse
Answer-4
velocity & impedence of RLC circuit was found by ---------------vector
Answer-Adding the Phase Vector
What happens to the strength of electro magnetic field when current passing through an inductor is halfed ________
a. ¼
b. ½
c. 2
d. 4
Answer-A
Fuses placed in series with a thermal trip = - type circuit breaker are used for
A.Time-delay protection
B.Short-circuit protection
C.Short duration surge protection
D.Sustained overload protection
Answer-D
Nice Post!! pretty informative..thanks for providing such a nice post.
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