Switch cabinet and corresponding electrical components knowledge
The switchgear is a complete set of power distribution devices that are used to assemble and protect the line and equipment according to a certain line plan. The internal components include: busbars (busbars) and circuit breakers. , conventional relays, integrated relay protection devices, measuring instruments, isolation knives, indicator lights, grounding knives, etc. Power Hacksaw,Junior Hacksaw,Electric Hacksaw,Mini Hacksaw ZHOUSHAN CHUNLEI HACKSAW CO.,LTD , https://www.bailei.com
The switchgear cabinet is a complete set of power distribution devices that are used to control the line and equipment according to a certain line scheme. The switchgear is divided into fixed and handcart type, and the input and exit line voltage. The grades can be divided into high-voltage switchgear (fixed and handcart) and low-voltage switchgear (fixed and drawer). The structure of the switchgear is generally similar, and is mainly divided into a busbar room, a circuit breaker room, a secondary control room (instrument room), and a feeder room, and steel plates are generally isolated between the rooms.
Internal components include: busbars (busbars), circuit breakers, conventional relays, integrated relay protection devices, metering instruments, isolation knives, indicator lights, grounding knives, etc.
Divided from the perspective of application:
(1) Incoming cabinet: Also known as the receiving cabinet, it is used to receive electrical energy from the grid (from the incoming line to the busbar), generally equipped with circuit breakers, CT, PT, isolation knives and other components.
(2) Outlet cabinet: also called feeder cabinet or power distribution cabinet, is the equipment used to distribute electric energy (from busbar to each outlet), and is generally equipped with circuit breaker, CT, PT, isolation knife and other components.
(3) Busbar connection cabinet: also called busbar branching cabinet, which is used to connect two busbars (from busbar to busbar). In single busbar section and double busbar system, busbar connection is often used to meet user choice. The requirements for different operating modes or guaranteed removal loads are available in the event of a fault.
(4) PT cabinet: The voltage transformer cabinet is generally installed directly on the busbar to detect the bus voltage and realize the protection function. Mainly installed voltage transformer PT, isolation knife, fuse and lightning arrester.
(5) Isolation cabinet: It is used to isolate the busbars at both ends or to isolate the power receiving equipment from the power supply equipment. It can provide the operator with a visible end point for maintenance and repair work. Since the isolation cabinet does not have the ability to break and switch the load current, the handrail of the isolation cabinet cannot be pushed and pulled in the case that the circuit breaker with which it is fitted is closed. In general applications, it is necessary to set the interlock between the auxiliary contact of the circuit breaker and the isolated handcart to prevent the operator from misoperation.
(6) Capacitor cabinet: also called compensation cabinet, used to improve the power factor of the power grid, or reactive power compensation, the main components are grouped capacitor banks, switching control loops and fuses connected in parallel Protective appliances such as devices. Generally installed side by side with the incoming line cabinet, one or more capacitor cabinets can be operated side by side. After the capacitor cabinet is disconnected from the grid, since the capacitor bank needs a period of time to complete the discharge process, it is not possible to directly touch the components in the cabinet, especially the capacitor bank; within a certain period of time after the power is cut off (according to the capacitor bank) Depending on the size of the capacity, such as: 1 minute), re-closing is not allowed to avoid overvoltage damage to the capacitor. When making automatic control functions, it is also necessary to pay attention to the reasonable number of switching times of each group of capacitor banks, so as to avoid a group of capacitors being damaged, while other groups are rarely switched.
(7) Metering cabinet: mainly used for metering electric energy (kWh), and also has high voltage and low voltage. Generally, it is equipped with isolation switch, fuse, CT, PT, active energy meter (traditional meter or digital meter). ), reactive energy meters, relays, and some other auxiliary secondary equipment (such as load monitors, etc.).
(8) GIS cabinet: also called closed combination electric cabinet, which is a closed combination of circuit breaker, disconnector, grounding switch, CT, PT, lightning arrester, busbar, etc. in the metal casing, and then has good insulation performance and arc extinguishing performance. The gas (usually SF6) is used as an insulation measure between phases and ground. It is suitable for power distribution and control in high-voltage and high-capacity power grids.
(9) Circuit breaker: Under normal working conditions, the circuit breaker is in the closed state (except for special applications), and the circuit is turned on. When the automatic control or protection control operation is performed, the circuit breaker can perform the breaking or closing operation of the circuit under the control of the integrated protection device. The circuit breaker not only can cut off the normal load current, but also can withstand the short-circuit current (multiple times or even several times of the normal working current) for a certain period of time, and can break the short-circuit current and cut off the faulty line and equipment. Therefore, the main function of the circuit breaker is to break and close the circuit (including breaking and turning on the normal current, breaking the short-circuit current).
Due to the inevitable arcing between the moving and stationary contacts of the circuit breaker during the breaking and closing of the circuit. In order to protect the contacts, reduce the loss of the contact material and reliably break the circuit, measures must be taken to extinguish the arc as soon as possible, one of which is to fill the moving and static contacts of the circuit breaker with different arc extinguishing media. According to the different circuit breakers of arc extinguishing medium, it can be divided into: oil circuit breaker (multi-oil, less oil), sulfur hexafluoride (SF6) circuit breaker, vacuum circuit breaker, air circuit breaker and so on. The main primary equipment in the high and low voltage switchgear that we often encounter in engineering is the circuit breaker.
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