The composition and function of incoming cabinet, outgoing cabinet, metering cabinet, PT cabinet, contact cabinet and isolation cabinet

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The power supply system is used to bring high voltage through transformer step-down to the required voltage level of the user and is equipped with protection, metering and distribution of the indoor integrated system.

Composition: incoming cabinet, metering cabinet, PT cabinet, outgoing cabinet, contact cabinet, isolation cabinet



1. Incoming cabinet

Incoming cabinet: is the switchgear introduced from the external power supply, generally from the power supply network into 10kV power supply, 10kV power supply through the switchgear to 10kV bus, the switchgear is the wire cabinet

Components: vacuum circuit breaker, isolation switch, three groups of three-coil current transformer, lightning arrester, live display, voltage transformer, wire and other components

Function: The main function is to distribute electricity. The inlet cabinet is generally equipped with a vacuum circuit breaker for breaking. The vacuum circuit breaker has the protection functions of short circuit and overcurrent prevention, etc. At the same time, it is equipped with an isolation switch for maintenance and protection of maintenance personnel. So the line cabinet has protection, measurement, monitoring and so on can achieve more comprehensive functions.

Protection of power incoming terminal:

1. Standby automatic input device, that is, automatic input device of standby power supply.

2. Lightning protection devices

3. Overvoltage and undervoltage protection

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

5. Quick break protection, over current protection

6. Zero sequence protection, grounding protection

8. Reclosing device,

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



2. Metering cabinet

Main components: current transformer, fuse, Vv connection voltage transformer, live display

Function: It is a kind of electric energy measuring device, which adopts the way of high supply and high meter, and reflects the electricity consumption of load through the measuring devices such as current transformer, voltage transformer and electricity meter. The user shall be responsible for protecting the seal of the metering device installed at the user's place from damage or loss.



3. PT cabinet

Major component: voltage transformer, isolator, fuse, arrester



1. Voltage measurement, providing the voltage loop of the meter

2, can provide operation box operation power supply

3. Installation of overvoltage protector for each bus

4, the need for relay protection, such as bus insulation, over voltage, under voltage, standby conditions

Wiring: Vv wiring, Y,yn wiring, YN,yn wiring



4. Outgoing cabinet

Outgoing cabinet: It is the switch cabinet where the bus distributes power to the power transformer. This switch cabinet is one of the 10kV outgoing cabinets.

Composition: three sets of three-COIL CURRENT transformer, isolation switch, circuit breaker, knife gate, live display device

Function: It mainly distributes electric energy, distributes the main power supply to each branch switch, and connects and disconnects the branch power supply to each branch passing by the overload protection box.



5. Contact cabinet

Contact cabinet, also known as bus segment cabinet, is used to connect two sections of bus equipment, in the single bus segment, double bus system is often used in the bus contact cabinet, to meet the requirements of users to choose different operation mode or to ensure the selection of load removal in case of failure.

Composition: isolation switch, circuit breaker, current transformer, live display device

Function: Generally plays the role of contact bus, when the two power supplies are sent at the same time, the contact will be interrupted in the middle (two different power supplies, usually can not coincide), when one of the power supply due to an accident or power failure, the contact cabinet will be automatically connected, to ensure that the user electricity, and when the original power failure end is restored, the contact cabinet will be automatically disconnected. In the original standby state.



6. Isolation cabinet

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

Function: IT is used to isolate both ends of the bus or to isolate the power device and the power supply device. It can provide a visible end point for the operator to facilitate repair and maintenance operations

The function of each component

Circuit breaker: when the circuit short-circuit or over-current fault can quickly cut off the power, to prevent the expansion of the fault, but also can be used as a general switch, to achieve the distribution and control of power, using electric operation.

Fuse: when the current rises abnormally to a certain height and a certain time, its own fuse cuts off the current, so as to play the role of protecting the safe operation of the circuit.

Isolation switch: used to isolate the power supply, disconnect the high-voltage maintenance equipment from the live equipment, is the flagship has a clearly visible disconnection point; The disconnector and the circuit breaker cooperate to reverse the switch according to the system operation mode, so as to change the system operation wiring mode.

Voltage transformer and current transformer: THE high voltage or large current is converted into standard low voltage (100V) or standard small current (5A or 1A, both refer to the rated value) according to the ratio, so as to realize the standardization and miniaturization of measuring instruments, protection equipment and automatic control equipment. At the same time, the transformer can also be used to separate the high voltage system to ensure the safety of life and equipment.

Arrester: through the action of parallel discharge gap or nonlinear resistance, the invading flow wave is cut to reduce the overvoltage value of the protected equipment


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