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Basic knowledge of distribution cabinet and distribution box

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Incoming cabinet: it refers to the switch cabinet that introduces power from the outside. Generally, 10kV power is introduced from the power supply network. 10kV power supplies send electric energy to 10kV bus through the switch cabinet. This switch cabinet is the incoming cabinet

Composition: vacuum circuit breaker, disconnector, three groups of three coil current transformers, lightning arrester, live display, voltage transformer, conductor and other components

Incoming cabinet

Function: the main function is to distribute electricity. The incoming cabinet is generally equipped with vacuum circuit breaker for disconnection. The vacuum circuit breaker has short circuit, anti overcurrent and other protection functions. At the same time, it is equipped with disconnector for maintenance and protection of maintenance personnel. In addition, the incoming cabinet is also equipped with current transformer, voltage transformer and measuring current and voltage value. Therefore, the incoming cabinet has protection, metering, monitoring and other functions, which can realize more comprehensive functions.

Incoming cabinet

Relevant protective devices of incoming cabinet

Protection of power incoming terminal:

1. Standby automatic switching device, i.e. automatic switching device of standby power supply.

2. Lightning protection device

3. Overvoltage and undervoltage protection

4. Inrush current protection: when the circuit breaker is closed with load, the trunk line generates an inrush current far greater than the working current of the circuit breaker, resulting in the switch can not be closed reliably with load. Inrush current protection device is to prevent false tripping caused by inrush current at the moment of closing and ensure reliable tripping of short circuit breaker with load.

5. Quick break protection and overcurrent protection

6. Zero sequence protection and grounding protection

8. Reclosing device

9. Low cycle protection (low frequency load shedding protection)

Metering cabinet

Main components: current transformer, fuse, voltage transformer with VV connection and live display

Function: it is a kind of electric energy metering device, which adopts the mode of high supply and high meter to reflect the power consumption of load through current transformer, voltage transformer, electric energy meter and other metering devices. The metering device installed at the user shall be protected and sealed by the user, and the device itself shall not be damaged or lost.

Metering cabinet

PT cabinet

Main components: voltage transformer, isolation knife, fuse and lightning arrester

PT cabinet

Function: 1. Voltage measurement, providing the voltage circuit of the measuring meter

2. Operation box operation power supply can be provided

3. Installation of overvoltage protector for each section of bus

4. Relay protection requirements, such as bus insulation, overvoltage, undervoltage and standby automatic switching conditions

Wiring mode: VV wiring, y, yn wiring, YN, yn wiring

Outgoing cabinet

Outgoing cabinet: it is the switch cabinet that distributes electric energy from the bus to the power transformer. This switch cabinet is one of the 10kV outgoing cabinets

Outgoing cabinet

Composition: three groups of three coil current transformers, disconnectors, circuit breakers, knife switches and live display devices

Function: it is mainly used to distribute energy, distribute the main power supply to each power branch switch, and connect and disconnect the branch power supply to each branch overcurrent overload protection box.

Contact cabinet

The contact cabinet is also called bus section cabinet, which is used to connect two sections of bus. The bus contact cabinet is often used in single bus section and double bus system to meet the requirements of users to select different operation modes or ensure selective load removal in case of fault.

Contact cabinet

Composition: disconnector, circuit breaker, current transformer and live display device

Function: it generally acts as a connecting bus. When two power supplies are powered on at the same time, the connection is disconnected from the middle (two different power supplies usually cannot overlap). When a certain section of power supply is powered off or powered off due to an accident, the contact cabinet will be automatically connected to ensure the power consumption of users. When the end of the original power failure is restored to be powered on, the contact cabinet will be automatically disconnected, In the original standby state.

Isolation cabinet

Composition: circuit breaker disconnector grounding switch current transformer voltage transformer arrester live display device

Isolation cabinet

Function: it is used to isolate buses at both ends or to isolate power receiving equipment and power supply equipment. It can provide a visible end point for operators to facilitate overhaul and maintenance

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