Assessment Test

Warning: mysql_connect(): Access denied for user 'lorque_wrdp1'@'localhost' (using password: YES) in /home/tmc2018/ on line 15

1. What is "the voltage per millimeter of insulation thickness that the insulation can withstand without breaking down" called?


2. What happens to the life expectancy of insulation for each 10o C rise in operating temperature?


3. What is the approximate discharge voltage produced by one cell of a wet type nickel- cadmium battery at 75% of charge?


4. What material are the plates of a wet cell NiCad storage battery made of?


5. What is the most reliable and preferred method for determining the state of charge of a wet-cell NiCad battery?


6. What will be the impact of reduced voltage applied to a motor during the starting period?


7. What is he most practical method of controlling the RPM of a multi-speed AC motor operating at a constant frequency?


8. Regarding an induction motor, what does the power developed by the rotor automatically adjust itself to?


9. Which type of AC single-phase motor will also operate on direct current?


10. What is the main function in the use of a capacitor for starting a single phase motor?


11. What is the main purpose of the auxiliary winding on a split-phase, single-phase motor?


12. What type of rotor is most commonly used in the split-phase family of single-phase motors?


13. Which statement is true concerning a split-phase induction motor?


14. A shaded-pole motor is a specific type of motor included in what class of motor?


15. Which of the listed motors will operate at the highest RPM, assuming that each operates at the same frequency?


16. How is the difference between the synchronous speed of a three phase induction motor and its operating speed correctly expressed?


17. In a three-phase, squirrel-cage type, induction motor, how is the primary rotating magnetic field established?


18. What is the characteristic of a wound-rotor induction motor, with a high resistance inserted in series with the rotor winding at startup?


19. What type of AC motor would use a rheostat in the rotor circuit to vary the speed of the motor?


20. A degree of control over the speed of a slip ring induction motor can be obtained by what means?


21. Which of the following physical characteristics does a three-phase wound-rotor induction motor possess that a squirrel cage induction motor does not?


22. By what means is a synchronous motor started and brought nearly to synchronous speed?


23. Concerning the operating characteristics of a synchronous motor, what statement is true?


24. Assuming that a three phase synchronous motor is separately excited, what statement is true concerning power supplies?


25. Occasionally a synchronous motor is configured without an external shaft to drive a load. In this case, the sole purpose of the synchronous motor is improving overall power factor of an electrical distribution system. What is the name of the synchronous motor so constructed?


26. Not only can a synchronous motor drive a load with greater efficiency than an induction motor, a fringe benefit of the synchronous motor is the ability for power factor correction. What statement is true?


27. In terms of voltage potential and current sources, how are shunt wound, series wound, and compound wound DC motors designed to operate?


28. How can the direction of rotation of a DC motor be reversed?


29. From the instant of start-up, through the acceleration period, and until the motor reaches rated speed, when is the counter EMF produced in the windings of a DC motor 'zero'?


30. Which of the following statements describes what will happen when both the polarity of the field poles, and the direction of current to the brushes of a DC motor are reversed?


31. If a DC motor has its armature and field connected across a resistor when the motor is disconnected from its power supply, what statement is true?


32. What is an advantage of DC motors over AC motors?


33. The torque produced by a DC motor armature is the multiplication product of two factors, one being the density of the magnetic flux which is dependent upon the field current. What is the other multiplication factor?


34. Which of the following types of DC motors is considered to produce the highest starting torque?


35. In a series wound motor, the current passing through the field windings also passes through what component?


36. How is the speed of a series wound winch motor controlled?


37. What type of DC motor is never connected to a belt driven load?


38. What type of DC motor has extremely high starting torque, but has poor inherent speed regulation? What type of DC motor has extremely high starting torque, but has poor inherent speed regulation?


39. What type of DC motor has relatively low starting torque, but has excellent inherent speed regulation?


40. In a shunt wound DC motor, how is the shunt field connected?


41. What are the characteristics of the field winding of a shunt wound motor?


42. What statement is true concerning speed control of a shunt wound DC motor?


43. Which of the listed DC compound motor connection schemes is the most commonly used?


44. When a compound wound DC motor is cumulatively compounded, what does this mean?


45. When a compound wound DC motor is differentially compounded, what does this mean?


46. Assuming that a cumulatively compounded DC motor is fitted with interpoles and compensating windings, normally how is the direction of rotation in such a DC motor reversed?


47. What is the purpose of an electro-magnetic relay?


48. Which of the following statements represents the main difference between a relay and a contactor?


49. What is the functional name of an electrical device which prevents simultaneous energization of loads thereby preventing damage or injury?


50. What is one function of the movable cams in a drum-type winch motor controller?


51. What is the name of the type of motor control circuit that will not permit automatic restarting after power is restored, following a power failure?


52. With what kind of starting equipment are most three-phase induction motors of five horsepower or less started?


53. Auto-transformer starters, sometimes called starting compensators, are sometimes used with larger polyphase induction motors. What function do they perform?


54. In general, what type of starter would be used to connect polyphase induction motors to full line voltage at the instant of start-up?


55. By what means is the burning of controller contacts due to arcing, when opening, prevented?


56. Which of the following statements about a three-phase wye connected alternator is correct?


57. Of the listed factors that influence the amount of RMS voltage induced in the windings of an AC generator operating at a constant 60 Hz frequency, which factor is variable during generator operation?


58. If the driving torque, such as that produced by a diesel engine, creates pulsations when coupled with a synchronous generator operating in parallel, the generator rotor may be periodically pulled ahead or behind its normal position as it rotates. How can this condition called hunting be reduced?


59. How are AC and DC generators are similar?


60. A DC generator which is used to supply direct current in order to provide magnetizing current to an AC generator field is commonly known as what?


61. Which of the methods listed below is used to provide the rotational torque to cause an AC generator to turn?


62. How will the value of the output frequency change if the load is removed from a turbo generator having a governor speed droop setting of 3%?


63. Two AC generators are operating in parallel and both are equipped with automatic voltage regulators. While standing watch, one generator is noted as having a greater lagging kvar value. In order to equalize the kvars between the generators manually, what should be done?


64. When paralleling two alternators the synchronizing lamps grow dim and are totally darkened as the synchroscope pointer approaches the 0° position. What does this indicate?


65. While paralleling two (2) AC generators using synchronizing lamps only, when will both lamps will go dark?


66. Diesel generators #1 and #2 are operating in parallel at near full load capacity. Diesel generator #1 suddenly trips out mechanically due to low lube oil pressure. The reverse power relay functions properly and trips generator #1 electrically off the board. Which of the following actions should you carry out FIRST?


67. When shore power is being connected to a ship in dry dock, what must be ensured, assuming that the ship's generators are rated at 450 VAC, 60Hz with a total capacity of 5000 kW?


68. Upon failure of the normal power supply, by what means is the emergency generator placed on the line and connected to the emergency bus?


69. By what means is an AC generator prevented from becoming motorized?


70. What is the purpose of the commutator and brushes on a DC generator?


71. Why are armature cores in a DC generator made of laminated steel sheets?


72. How are the field windings of a DC shunt generator connected?


73. What two factors determine the magnitude of the generated voltage of a DC generator?


74. For the purposes of generating a DC voltage, which of the following factors is subject to vary for a particular generator installation while in operation?


75. What statement is true concerning the use of commutating poles (also known as interpoles) in DC generators?


76. What statement is true concerning the use of compensating windings in DC generators?


77. What is the purpose of the series field used in a stabilized shunt DC generator?


78. With what device is the simplest method of controlling the terminal voltage of compound-wound DC generator?


79. Prior to closing the circuit breaker when paralleling two DC generators, what must you be certain of?


80. Which of the methods listed is used to maintain equal load sharing between two compound wound DC generators operating in parallel?


81. By what means is a DC generator prevented from becoming motorized if paralleling is accomplished without an equalizer?


82. How are fuses usually rated?


83. What is the characteristic that is associated with an "instantaneous-trip" single- element type fuse?


84. Due to the operating characteristics of the system, time lag fuses (or dual-element fuses) are necessary for use in what types of circuits?


85. Fuses are sometimes placed in series with a thermal trip-type circuit breaker. What is the purpose of a fuse used in this arrangement?


86. What is the basic similarity between a circuit breaker and a fuse?


87. The arc resulting from the tripping of a circuit breaker is prevented from damaging the contacts. How is this done?


88. A thermal-magnetic circuit breaker for a 300 KW alternator is rated at 500 amperes at full continuous load. Which of the following conditions will trip the breaker?


89. Relative to the number of turns of a secondary winding of a step-up transformer, what will be the number of turns of a primary winding?


90. If the primary winding of a voltage transformer is connected to a steady DC source, self-inductance and mutual inductance is not possible. As a result, what part of the transformer will result in current overload?


91. What is the purpose of a potential transformer in an electric circuit?


92. Which of the following statements is true concerning step-down transformer operation?


93. When a transformer is used to step down voltage, what statement is true?


94. What is the primary purpose associated with the use of transformers onboard ships with AC generators?


95. An autotransformer is equipped with a 50% tap, a 65% tap, and an 80% tap. Which of the following statements is true concerning a load connected to the 50% tap?


96. Besides the fluorescent lamp itself and possibly a starter, which of the following components is included in a fluorescent lighting fixture?


97. Incandescent lamps are classified according to the shape of the bulb and the type of service, as well as the size and style of the base. How are incandescent lamps rated?


98. How is electrical conductor insulation classed? Example: insulation class H


99. Which of the following materials is a good electrical insulator?


100. Which of the following is the only known perfect dielectric for the purpose of serving as electrical insulation?


Total Rating:

click here to go to review now