competence 7.2

66問 • 1年前

ERNO ENRIQUE JOMENTO

通報

問題一覧

62. What is used in most for starting three-phase induction motors of five (5) horsepower or less ?

across-the-line starters

63. Periodic testing of circuit breakers is necessary to assure that a correct rated and properly installed unit

will continue to provide the original degree of protection

64. You are testing the insulation in an AC generator with with a megohmeter. the resistance value of a dry, clean winding will_

continue to rise as the test potential is maintained, becoming fairly steady as the leakage current stabilizes

65. Which of the following data is required to draw the circle diagram for an induction motor?

Bolck rotor test, no load test and stator resistance test

66. The removal of paint from electrical equipment such as generators, should be cautiously undertaken because

the paint dust is composed of abrasive and semi-conducting materials which impair insulation

67. A reversible electric motor with worm gear that is connected to the flywheel to position engine parts is the

turning gear

68. If a small electric motor is immersed in salt water it should be I. washed in fresh water II. dried in an oven III. blow air until it dries

I only.

69. To carry out an insulation resistance test, one terminal of the megohmmeter should be connected to the winding, with the other terminal being connected to the

frame of the machine

70. Before working on an electric motor starter panel located on the main deck, what should you do FIRST?

Open the circuit breaker and tag out

71. A fuse the blows often should be replaced only with a fuse of __.

the recommended current and voltage rating

72. Electrical Insulating rubber gloves should be dielectrically tested every how many months?

6 months

73. It is a type of temperature sensor that has the characteristic of being very accurate, linear and has a good long term stability.

RTD'S

74. A self-excited DC generator fails to come up to its normal 440 volts. What could be the probable cause?

low armature speed

75. A common type of protective covering used on electrical conductors is,

Fibrous braid

76. The air gap provided in induction motors should be checked periodically with a feeler gage to detect an unequal air gap and

Mechanical damage to rotor

77. A temperature instrumentation system for an accomodation reefer room consists of a resistance temperature detector (RTD), a measuring bridge circuit and a meter or alarm circuit. Which of the following is true concering the measuring bridge circuit ?

The ressistance bridge is said to be balanced when its output voltage is zero

78. Electrically operated safety devices on auxiliary diesel engines functions to stop the engine by

shutting off fuel supply

79. A molded-case circuit breaker provides protection against short circuits by using alan ?

electromagnet

80. The proper way to apply plastic electrical tape to an electric cable splice is to

wind the tape so that each turn overlaps the turn before it

81. The division of kilowatt load between two paralleled alternators is determined by the ?.

load-speed characteristics of the governors

82. What is the result if the solenoid coil burns on a cargo winch with an electrical brake?

The brake will be set by spring force.

83. The air gap provided an induction motor should be checked periodically with a feeler gage to detect

any increase in rotor bearing wear

84. Encrusted dirt accumulated inside a motor should be removed with a

Fiber scraper

85. A temperature instrumentation system to an engine room console consists of a resistance temperature detector (RTD), a measuring bridge circuit , and a meter (or alarm circuit). Which of the following statements is true concerning the measuring bridge circuit?

The resistance bridge is said to be balanced when its output voltage is zero

86. When a replacing a fuse with one of a higher rating than the original, which of the following is true?

It endangers the apparatus it is supposed to protect

87. The purpose of a motor under voltage protection device is to

prevent high armature current when power is restored

88. The power scale of circle diagram of an induction motor can be found from

short-circuit test only.

89. What electrical apparatus can test insulating efficiency in an electric installation?

Megger tester

90. When reading electrical motor controller diagrams, it helps to know that

current paths in the power circuit are drawn as heavy lines and in control circuit as lighter lines

91. What devices is fitted to prevent the generator windings from absorbing moisture while at standstill?

Space heater

92. Any electric motor can be constructed to be?

explosion proof

93. A common type of protective covering used on electrical conductors is

rubber or plastic

94. Which of the following statements concerning the maintenance of solid-silver Contacts in relay and auxiliary control circuits is correct?

They should be filed with a fine-cut file when projections extend beyond the contact surface

95. What can you do if the generator is exposed to rain or any water?

Make a megger test

96. What is the cause when an alternator failed to produce line voltage?

exciter generator failure

97. Moisture as a result of condensation occurring inside of the cargo winch master switches, can be reduced by?

using strip heaters inside the switch box

98. Regulations require each motor controller to have a wiring diagram located

on the inside of the controller door

99. A device which can be used to check the calibration of a circuit breaker is a

portable low voltage high current testing unit

100. Which of the following statements concerning analog and digital devices are correct?

The variables in digital systems are fixed quantities and the variables in analog systems are continuous quantities.

101. When a megohmmeter is being used to test insulation resistance, current leakage along the surface of the insulation is indicated by the megohmmeter's pointer ?

kicking slightly down scale as voltage is applied

102. In using the Rheostat, what do you call the circuit of the motor to adjust the speed?

Induction motor with wound-rotor

103. How can you restore the charge of a lead-acid battery?

passing a direct electric current through the cell

104. In an impressed current cathodic protection system, what is anode

insulated from the hull and does not waste away,

105. Complete maintenance of electrical motors should include periodic checks for machine

vibration

106. The automatic voltage regulators provide on switch boards has function to

vary the field excitation to the generators

107. If a delicate component must be soldered into a circuit the component may be protected from the heat of the soldering process by.

Using a thermal shunt

108. What maximum voltage can Class 00 electrical insulating rubber gloves can be used?

500 volts

109. Which of the following statements represents the FIRST step in seating new brushes on slip rings?

Lay sandpaper between the brush and the slip ring and slide the sandpaper back and forth under the brush.

110. Which of the following statements is true concerning the cleaning of electrical contacts?

Delicate parts should be cleaned with a brush and an approved safety solvent.

111. What indicates the third color band on a resistor?

number of zeros following the first two significant figures in the resistance value

112. What would indicate ground in a particular phase 3 - phase low voltage distribution system?

dark or dim switchboard ground detecting light

113. While trouble shooting a circuit in an engine room central control console, a resistor is suspected of being faulty. Which of the following precautions must be observed if an ohm meter is to be use to check its value?

Resistor circuit must be de-energized and at least one end of the component isolated

114. Which of the following statements best describes the material known as varnished cambric?

Cotton cloth coated with insulating varnish.

115. What is the first step to properly use a hook-on-type voltammeter in checking current flow?

hook the jaws of the instrument around the insulated conductor

116. Upon failure of the normal power supply, the emergency generator is placed on the line by the

automatic bus transfer devise

117. 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. What does this element consist of?

second bimetal element

118. Which of the listed precautions should be observed before spraying liquid solvent on the insulation of an electric motor?

Disconnect the motor from the power source.

119. The electrolyte in a lead-acid storage battery consists of distilled water and ?

sulfuric acid

120. The insulation resistance of electric equipment and machinery should be tested for lowest normal insulation valves

immediately after shutting down of the machine

121. How much is the typical resistance of the body from hand to foot when dry?

500 ohms

122. How will you remove a tubular fuse from a fuse panel with ?.

fuse pullers

123. Which device that commonly utilizes the principle of electromagnetic induction?

transformer

124. When a lead-acid battery begins gassing freely while receiving a normal charge, what should you do when charging?

be decreased

125. In the circle diagram for induction motor, the diameter of the circle represents

rotor current

126. What is a three-layer bidirectional device used primarily as a trggering device with junctions heavily and equally doped?

Diac

127. Two contributors of electronic console failures are heat and vibration. To combine some of their effect, preventive maintenance procedures should include

periodic changing or cleaning of console ventilation and control room air conditioning filters

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