1. Why is it necessary to install expansion joints on hard busbars?
Objects have thermal expansion and contraction characteristics, and the length of the busbar will change due to heating during operation. To avoid excessive stress and damage to the busbar and supporting insulators caused by thermal expansion and contraction, expansion joints should be installed on the hard busbar.
2. What is a full insulated transformer? What is a semi insulated transformer?
Semi insulation refers to the main insulation of the winding near the neutral point of a transformer, which has a lower insulation level than the end winding. In contrast, the insulation level of the first and end windings of a transformer is generally called full insulation.
3. What is the main function of transformers in the power system?
The role of transformers in power systems is to transform voltage for the purpose of facilitating power transmission. After the voltage is boosted by a step-up transformer, it can reduce line losses, improve the economy of power transmission, and achieve the goal of long-distance power transmission. And the step-down transformer can convert high voltage into the various levels of voltage required by users, meeting their needs.
4. What are the hazards of bushing cracks?
Cracks in the bushing can reduce the insulation strength and cause further damage to the insulation until complete breakdown occurs. When water freezes in the cracks, it may also cause the bushing to swell and crack. It can be seen that cracks in the bushing pose a significant threat to the safe operation of transformers.
5. What is the function of a high-voltage circuit breaker?
High voltage circuit breakers can not only cut off and connect the no-load current and load current in normal high-voltage circuits, but also cooperate with protection devices and automatic devices to quickly cut off the fault current in case of system failure, prevent accidents from expanding, and ensure the safe operation of the system.
6. What is the function of a wave blocker?
Blocker is an indispensable high-frequency communication component for carrier communication and high-frequency protection. It prevents high-frequency current from leaking to other branches and reduces high-frequency energy loss.
7. What is the function of a current transformer?
Current transformers convert large currents into small currents in a certain proportion, providing currents for various instrument use and relay protection, and isolating the secondary system from high voltage. It not only ensures the safety of personnel and equipment, but also simplifies and standardizes the manufacturing of instruments and relays, improving economic efficiency.
8. What are the wiring methods for current transformers?
The wiring method of current transformers includes using two current transformers with two-phase V-shaped wiring and two-phase current difference wiring; There are three-phase Y-shaped connections, three-phase delta connections, and zero sequence connections using three current transformers.
9. How many types of reactive power sources are there in the power system?
The reactive power sources in the power system include:
① Synchronous generators;
② Adjust the camera;
③ Parallel compensation capacitor;
④ Series compensation capacitor;
⑤ Static compensator.
10. Why install a set of ZnO lightning arresters between power capacitors and their circuit breakers?
Installing ZnO lightning arresters can prevent operational overvoltage that may occur during the pulling and closing of power capacitors, ensuring the safe operation of electrical equipment.
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