The maintenance grounding switch is located next to the isolating switch on both sides of the circuit breaker, and its main purpose is to ground the two sides of the circuit breaker during maintenance. This ensures safety for personnel working on the equipment.
The fast grounding switch, on the other hand, is installed on the line side of the outgoing disconnecting switch in the outgoing circuit. It has two primary functions:
1. It can open and close parallel overhead lines, helping to manage the capacitive current caused by electrostatic induction and electromagnetic coupling.
2. In case of internal insulation flashover or arcing inside the outer casing, the fast grounding switch quickly grounds the main circuit, allowing the circuit breaker to interrupt the fault current effectively.
The coordination between the circuit breaker and the fast grounding switch can be understood from two perspectives: tripping and reclosing.
From the tripping perspective, it's quite straightforward. When a single-phase fault occurs on the line, the switches on both sides of the faulted phase are opened. However, due to electromagnetic coupling between the healthy phase and the faulty phase, a potential supply current may appear, which hinders arc extinction. To reduce this sub-surface current, an automatic device triggers the fast grounding switch on both sides to close immediately, aiding in rapid arc extinction.
From the reclosing standpoint, the fast grounding switch plays a critical role. The process involves several steps:
1. A single-phase grounding short-circuit occurs, causing an arc.
2. The circuit breakers at both ends of the faulted phase trip, extinguishing the initial arc but potentially creating a secondary arc due to residual power.
3. The fast grounding switch in the faulted phase is activated, grounding the system and extinguishing the secondary arc.
4. After the arc is cleared, the fast grounding switch is opened.
5. Finally, the circuit breaker performs a reclosing operation to restore power.
This coordinated action helps improve system reliability and reduces the risk of prolonged outages.
Electric pole, also known as a telephone pole or telegraph pole, is a tall structure used to support overhead power lines and other utilities, such as telephone and cable lines. These poles, typically made of wood, metal or concrete, are installed along roadsides, in residential and rural areas to deliver electricity and other services to homes and businesses. The height and design of poles can vary depending on the specific requirements of the utility company and the location of the poles.
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