1. [Single-choice question] The secondary wiring diagram of relay protection composed of discrete components, according to its use, can be divided into schematic wiring diagram and ( ). (C) A. Expanded diagram B. Logic block diagram C. Installation wiring diagram 2. [Single-choice question] For the undervoltage protection that operates when the voltage drops during a fault, to ensure the protection operates, the sensitivity coefficient must be ( ). (A) A. Greater than 1 B. Less than 1 C. Equal to 1 3. [Single-choice question] The sensitivity of the overcurrent protection with undervoltage starting for transformers is ( ) compared to that of the definite-time overcurrent protection. (B) A. Lower B. Higher C. Unchanged 4. [Single-choice question] In transformer protection, ( ) serves as the backup protection for ground faults in the transformer and adjacent components. (B) A. Overcurrent protection B. Zero-sequence current protection C. Instantaneous overcurrent protection
5. [Single-choice question] The magnetizing inrush current of a transformer contains a significant ( ) component, causing the waveform to shift to one side of the time axis. (B) A. Periodic B. Non-periodic C. Rectangular wave D. Fundamental wave 6. [Single-choice question] After a transformer fault occurs, it should be ( ). (D) A. Strengthen monitoring B. Continue running C. Run until it cannot operate and then disconnect D. Immediately remove the transformer from the system 7. [Single-choice question] The main component of transformer gas protection is ( ). (C) A. Current relay B. Voltage relay C. Gas relay D. Intermediate relay 8. [Single-choice question] The main component of transformer gas protection is the gas relay, also known as ( ). (B) A. Current relay B. Buchholz relay C. Voltage relay D. Intermediate relay
9. [Single-choice question] Inter-turn short circuit in one phase winding and ( ), etc. (B) A. Phase-to-phase fault on the lead wire B. Phase-to-phase fault between windings C. Bushing flashover fault on the lead wire D. Single-phase ground fault caused by bushing breakage through the shell 10. [Single-choice question] The intermediate relay in the transformer Buchholz protection wiring has the function of ( ) to prevent unstable contact due to unstable gas flow and oil flow during operation. (B) A. Reclosing B. Self-holding C. Time delay D. Automatic transfer switching 11. [Single-choice question] The operating current of the transformer instantaneous overcurrent protection is set according to the maximum short-circuit current flowing through the protection when a short circuit occurs on the load-side busbar of the transformer, and also to avoid ( ). (B) A. The maximum short-circuit current flowing through the protection when a short circuit occurs on the power supply-side busbar of the transformer B. The magnetizing inrush current when the transformer is energized with no load C. Maximum load current D. Minimum load current 12. [Single-choice question] The sensitivity check of the transformer instantaneous overcurrent protection requires, according to regulations, ( ). (A) A. >2 B. >4
C. <2 D. <4 13. [Single-choice question] The operating current of the current element of the transformer overcurrent protection is set according to the maximum ( ) that the transformer may experience. (C) A. Three-phase short-circuit current B. Minimum two-phase short-circuit current C. Load current D. Magnetizing inrush current 14. [Single-choice question] The transformer overload protection is generally connected to ( ), and when overload occurs, it sends a signal after a time delay. (A) A. One-phase current B. Two-phase current C. Three-phase current 15. [Single-choice question] The transformer zero-sequence overvoltage protection consists of ( ) and a time element. (B) A. Current element B. Zero-sequence voltage element C. Power element 16. [Single-choice question] According to the system structure, substation automation systems can be divided into centralized, ( ), and distributed types. (C) A. On-site type B. Microcomputer type C. Distributed type
D. Master-slave type 17. [Single-choice question] The one-time wiring scheme for automatic transfer switching equipment can be divided into ( ) and dark standby mode according to the standby mode. (B) A. Line standby B. Explicit standby C. Transformer standby D. Busbar 18. [Single-choice question] The automatic transfer switching device should ensure that ( ) can be put into operation only after the working power supply is disconnected. (A) A. Standby power supply B. Working busbar C. Working line 19. [Single-choice question] In the differential protection of a transformer during an external fault, the current flowing into the differential relay is ( ). (C) A. High-voltage side current B. Low-voltage side current C. Unbalanced current D. Fault current 20. [Single-choice question] The installation wiring diagram includes the panel layout diagram, ( ), and terminal block diagram. (B) A. Schematic wiring diagram B. Rear panel wiring diagram
C. Flowchart D. Logic block diagram 21. [Single-choice question] For a radial power grid with a single-side power supply, the farther the short-circuit point is from the system power source, the ( ) the short-circuit current. (A) A. Smaller B. Larger C. Equal regardless of distance 22. [Single-choice question] For motors with a capacity less than 2MW and where the instantaneous overcurrent protection cannot meet the sensitivity requirements, ( ) is adopted. (C) A. Undervoltage protection B. Starting time overlong protection C. Longitudinal differential protection 23. [Single-choice question] Microcomputer protection refers to the protection constructed with microcomputers, microcontrollers, etc., as the core components. (B) A. Low-voltage switchgear B. Relay protection C. High-voltage switchgear D. Simulation line 24. [Single-choice question] When a circuit breaker trips due to a fault, a buzzer sound signal is emitted, which is called ( ). (A) A. Accident signal B. Warning signal C. Position signal
D. Contact signal 25. [Single-choice question] In the circuit breaker position signal, when the circuit breaker is in the open position, ( ). (A) A. Green light is on B. Red light is on C. Yellow light is on D. Red light flashes 26. [Single-choice question] In the circuit breaker control circuit, when the operating power supply voltage is ( ), it is called weak-current control. (A) A. 48V and below B. 110V or 220V C. 380V D. 10kV 27. [Single-choice question] The intermediate link in the power system that connects ( ) and users is called the power grid. (C) A. Transmission lines B. Transformers C. Power plants 28. [Single-choice question] The positive-sequence overcurrent protection of a motor can serve as the motor's ( ). (C) A. Stalled rotor protection B. Starting time overlong protection C. Symmetrical overload protection
C. Avoid the minimum starting current of the motor 30. [Single-choice question] When an external two-phase short circuit occurs in a motor, the negative-sequence current of the motor is ( ) the positive-sequence current. (A)
C. Equal to 31. [Single-choice question] In the longitudinal differential protection wiring of a motor, one side of the current transformer is connected to the motor terminal, and the other side is connected to ( ). (C) A. The motor winding
C. The corresponding phases on the neutral point side 32. [Single-choice question] The longitudinal differential protection wiring of a motor adopts the ratio braking characteristic, which should ensure to avoid the unbalanced current in the differential circuit during full-voltage starting, normal operation, and ( ) of the motor. (A)
C. Internal two-phase short circuit 33. [Single-choice question] When the voltage transformer primary or secondary circuit breaks during motor operation, the undervoltage protection ( ). (C)
