Electrician Skill Qualification Assessment Question Bank

Author: Chief Editor: Shangpinyi
Publisher:
Publish Date: 2002-01-01
Features: Based on the "Occupational Skill Identification Specification (Assessment Outline) for Electricians" jointly issued by the Ministry of Labor and Social Security, it aligns with the content of "Mechanical Worker Vocational and Technical Training Textbooks (Electrical Engineering)." It is divided into three parts: (Primary Worker), (Intermediate Worker), and (Senior Worker). The test questions include knowledge requirement questions (such as true/false, multiple-choice, calculation, short-answer, and drawing questions) and skill requirement questions, as well as sample knowledge requirement assessment papers. All questions and papers come with standard answers at the end of the book. This question bank can be used by industrial and mining enterprises and various assessment departments for worker evaluation and by vocational and technical schools and technical schools for teachers to create exam papers for electrical engineering students. It is also suitable for electricians and students for self-study, self-assessment, and exam preparation.
Excerpt:
71. The boom consists of a U-shaped iron fork and a wooden rod, commonly used to erect electric poles over 9 meters tall. ()
72. Safety belts and safety harnesses are used for climbing poles, with one end tied to the top of the pole, or to the crossarm, insulator, or tensioner. ()
73. Insulated gloves can still be used if there is slight leakage. ()
74. Insulated boots can also be used as acid-base and oil-resistant boots. ()
75. Insulated gloves are generally used as auxiliary safety tools for high-voltage live operation with insulated sticks. ()
76. Insulated gloves and insulated boots undergo preventive testing every six months. ()
77. Copper has excellent electrical and thermal conductivity, high mechanical strength, but is easily oxidized at high temperatures, melts quickly, and is suitable for rapid melting protection of transistors. ()
78. Lead-tin alloy is used as slow-melting material for motor protection. ()
79. The main function of insulating materials is to isolate charged or differently polarized conductors, allowing current to flow in the specified direction. In some cases, insulating materials also serve mechanical support, conductor protection, and electric arc suppression. ()
80. Permanent magnet motors are made of soft magnetic materials. ()
81. Carbon and graphite conduct electricity well, have good thermal conductivity, and are resistant to high temperatures, making them suitable for making brushes in electrical engineering.
82. Low-melting-point metals like tin and lead, which melt slowly, are suitable for high-voltage circuit breakers.
83. The performance requirements for high-voltage contact points and low-voltage contact points are the same, and the materials used are also the same. ()
84. Soft magnetic materials have high magnetic permeability, low coercivity, and can generate high magnetic induction strength under low external magnetic fields. As the external magnetic field increases, they quickly reach saturation. When the external magnetic field is removed, the magnetism almost disappears.
85. (Constantan), (Nickel-chromium-based alloy), and (Manganin) are commonly used to manufacture potentiometers and sliding resistors. They have good corrosion resistance, smooth surfaces, small and stable contact resistance.
86. (Alnico) material used in sensors, speakers, and microwave devices is a permanent magnet material that provides a constant magnetic field in a certain space.
87. The current-carrying capacity ratio of copper and aluminum wires is 1:0.76. In practical applications, if copper wire replaces aluminum wire, the cross-sectional area can be reduced by one grade.
88. The LGJ type steel-core aluminum stranded wire has a steel core to enhance mechanical strength and aluminum strands for current transmission. This wire is used for overhead lines with voltages of 10–35kV and above.
89. When connecting aluminum wires, they cannot be spooled or twisted like copper wires, not just because aluminum wires have poor mechanical strength.
90. Overhead lines generally use multi-strand bare wires, but insulated wires are often used in factory areas for safety.
91. The cross-sectional area of low-voltage power line conductors is generally selected and verified based on heating conditions, without considering economic current density.
92. When the cross-sectional area of line conductors is fixed, the heavier the load (line current), the smaller the voltage drop, and the higher the load-side voltage.
93. The safe current-carrying capacity of conductors varies with different ambient temperatures. Higher temperatures result in higher safe current-carrying capacity.
94. When steel-core aluminum stranded wire passes through alternating current, due to the skin effect of alternating current, the actual current flows only through the aluminum strands, so its effective cross-sectional area is only that of the aluminum strands.
95. The thermal resistance coefficient of soil affects the heat dissipation of buried cables, thus influencing their safe current-carrying capacity. A higher thermal resistance coefficient results in a higher safe current-carrying capacity.
96. Insulated wires in cable trays, when the cable tray is installed on a wall or bracket, the total cross-sectional area of the wires should not exceed 20% of the effective cross-sectional area of the cable tray.
97. The wall thickness of conduit (TC) is thin, and its nominal diameter refers to its inner diameter.
98. Polyvinyl chloride semi-rigid plastic conduit and polyvinyl chloride corrugated plastic conduit have good flexibility, corrosion resistance, and flame-retardant properties, making them suitable for concealed installation in building projects.
99. Conductors installed in conduit can have splices inside the conduit.