Power distribution operation test questions (volume B) - Solutions - Huaqiang Electronic Network

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First, the true or false questions:
1. It is strictly prohibited for staff to move or remove the fence, grounding wire, and signboard during work. ( )
2. It is not allowed to directly pull the arrester with the isolating switch during rain and snow. ( )
3. In case of an electric shock, fire, or critical equipment failure, the duty officer has the right to handle it first and then report to the dispatcher. ( )
4. In a 6–10 kV ungrounded system, when a single-phase ground fault occurs, the phase voltage of the non-fault phase will decrease simultaneously. ( )
5. The impact closing test on a newly commissioned transformer checks whether the main circuit breaker on each side can withstand operating overvoltage. ( )
6. Before measuring insulation resistance, the device under test must be discharged to ground, and others are prohibited from approaching during measurement. ( )
7. When power-off maintenance is performed, the operating power of the open circuit breaker and disconnector should be removed, and the isolation switch operation handle must be locked. ( )
8. The transformer oil level gauge is used to indicate the oil level in the oil pillow. ( )
9. During a switching operation task, personnel can be changed in case of special circumstances. ( )
10. The isolating switch can directly pull 110 kV and 10 kV no-load lines. ( )
11. The magnetic field of the induced current is always opposite to the original magnetic field. ( )
12. The fluctuation range of DC bus voltage should not exceed ±5%. ( )
13. The current transformer separates high voltage from secondary equipment such as instruments and protection devices, ensuring safety for operators and equipment. ( )
14. The operating sequence for horizontally or triangularly arranged high-voltage fuses is: first the two sides, then the middle. ( )
15. Internal overvoltage includes operating overvoltage, resonant overvoltage, and power frequency overvoltage. ( ) Second, multiple-choice questions:
1. In a DC circuit, inductance is equivalent to ( ).
A. Open circuit B. Short circuit C. No presence D. Closed circuit
2. The operation items on the operation ticket must include the check item, which should be filled with a double name, i.e., the device ( ).
A. Location and number B. Name and location C. Name and meter D. Name and number
3. The temperature of the battery room is generally required to remain in ( ).
A. 5–8°C or less B. Not exceeding 20°C C. 10–30°C
4. When the isolating switch is misoperated, the handling method should be ( ).
A. Immediately open B. Immediately close C. Do not open again if mismatched, and close before the arc breaks
5. The vent of the SF₆ power distribution room should be set at ( ).
A. Indoor bottom B. Indoor top C. Indoor center
6. If the transformer nameplate indicates rated voltage Ue±2×2.5%, the transformer ( ).
A. Three-stage voltage regulation B. Five-stage voltage regulation C. On-load voltage regulation
7. When a short-circuit fault occurs in the power system, the voltage usually ( ).
A. Rises sharply B. Drops sharply C. Becomes more stable D. Is unaffected
8. If the transformer neutral point is grounded, the transformer casing ( ).
A. Must still be grounded B. Can no longer be re-grounded C. Depends on the grounding location
9. When oiling the transformer, the oil level should be raised to the position corresponding to ( ).
A. Ambient temperature B. Oil temperature C. Winding temperature
10. The differential protection range of the transformer covers ( ).
A. Low-voltage side B. Medium-voltage side C. Equipment between current transformers on both sides of the transformer
11. If gas is present in the transformer gas relay ( ).
A. Indicates a fault inside B. Not necessarily a fault C. Indicates a major fault D. No fault
12. Before inputting the transformer differential protection ( ), measure the phase and voltage.
A. No load B. With load C. Not necessarily D. A little load
13. The minimum safe distance between the normal working area and live equipment in a 10 kV power distribution room is ( ).
A. 0.35 m B. 0.40 m C. 0.50 m
14. To reduce the rising speed of the recovery voltage between the contacts and prevent oscillating overvoltage, a ( ) is sometimes installed between the circuit breaker contacts.
A. Voltage equalizing capacitor B. Series capacitor C. Voltage equalizing belt
15. If one phase of the low-voltage side of the voltage transformer shows zero voltage, and the other two phases remain unchanged, while the line voltage is reduced by two, it indicates ( ).
A. Two-phase fuse break on the low-voltage side B. One-phase lead wire break on the low-voltage side
C. One-phase lead wire break on the high-voltage side D. Two-phase lead wire break on the high-voltage side Third, fill in the blanks:
1. The power safety work regulations stipulate that the organizational measures to ensure safety include the ________ system, the work permit system, the ________ system, and the ________ system.
2. When operating the switch, the guardian must __________, and the operator must __________, and the check must be correct. After the guardian issues the order, the operator may proceed.
3. When checking for electricity, use an electroscope of the appropriate voltage level to check the power on each side of the access line of the maintenance equipment. Before testing, perform a test on __________ to confirm the electroscope is in good condition.
4. The maintenance equipment and the circuit breaker (switch) and disconnector (knife switch) on the incoming side should have their __________ and __________ disconnected, and the operation handle of the isolating switch (knife gate) should be locked to prevent accidental power supply.
5. Personnel who have been approved by company leaders to independently inspect high-voltage equipment shall not perform other tasks during patrols and must not be blocked by __________ or __________.
6. The operating status of substation equipment is divided into four states: operation, __________, __________, and __________.
7. The structure of the isolating switch is characterized by __________, and lacks __________, so it cannot cut or close __________ circuits.
8. The input of a no-load transformer will produce __________.
9. For fire fighting of live equipment, dry powder extinguishers, carbon dioxide extinguishers, etc., should be used. __________ should not be used for fire fighting.
10. The secondary side of the transformer must be __________ to ensure the safety of personnel and equipment. Fourth, calculation problem:
A three-phase SZL—31500/38.5 kV transformer has a rated capacity of 31500 kVA, with a primary rated voltage of U1e = 110 kV and a secondary rated voltage of U2e = 38.5 kV. Calculate the rated currents on the primary and secondary sides.