The power supply system, an essential infrastructure for modern urban life, carries the crucial mission of safely and stably delivering high-voltage electricity to every household. Through ingenious engineering design and sophisticated equipment configuration, this system achieves multiple functions, including voltage reduction, protection, metering, and distribution, providing users with reliable and efficient power services. This article will detail the components and functions of incoming line cabinets, metering cabinets, PT cabinets, outgoing line cabinets, interconnection cabinets, and isolation cabinets.
Ⅰ. Incoming Cabinet
Incoming Cabinet: This is the switchgear that receives power from an external source. Typically, it draws 10kV power from the grid. This 10kV power source then passes through the switchgear and transmits the power to the 10kV busbar. This switchgear is called the incoming cabinet.
Components: Vacuum circuit breaker, disconnector, three sets of three-coil current transformers, lightning arrester, live indicator, voltage transformer, conductors, and other components.
Function: Its primary function is to distribute power. A line feeder cabinet is typically equipped with a vacuum circuit breaker for disconnection. This vacuum circuit breaker provides short-circuit and overcurrent protection, along with an isolating switch for maintenance personnel. The line feeder cabinet is also equipped with current and voltage transformers for current and voltage measurement. Therefore, the line feeder cabinet combines protection, metering, and monitoring functions to achieve a wide range of comprehensive functions.
Protection of power supply line:
1. Automatic backup power supply (APS), which automatically switches on the backup power supply.
2. Lightning protection device
3. Overvoltage and undervoltage protection
4. Inrush protection: When closing a circuit breaker under load, the mains generates an inrush current far greater than the circuit breaker's operating current, preventing the circuit breaker from reliably closing under load. The inrush protection device prevents false tripping caused by the instantaneous inrush current during closing, ensuring reliable tripping of the circuit breaker under load.
5. Instantaneous trip protection, overcurrent protection
6. Zero-sequence protection, ground fault protection
8. Reclosing device
9. Under-frequency protection (low-frequency load shedding protection)
Ⅱ. Metering Cabinet
Main Components: Current transformer, fuse, VV voltage transformer, and live indicator
Function: This device is a type of electric energy metering device that uses a high-supply, high-metering method to measure power consumption and reflect load power consumption through current transformers, voltage transformers, and other measuring devices. Users are responsible for protecting the seal of metering devices installed at their premises and preventing the device itself from damage or loss.
Ⅲ. PT Cabinet
Main Components: Voltage Transformer, Isolating Switch, Fuse, Lightning Arrester
Functions:
1. Voltage measurement, providing a voltage circuit for measuring meters
2. Providing power to the operating box
3. Installing overvoltage protectors for each bus section
4. Relay protection requirements, such as busbar insulation, overvoltage, undervoltage, and backup automatic switching conditions
Wiring options: Vv, Y, Yn, YN, Yn
Ⅳ. Outgoing Line Cabinet
Outgoing Line Cabinet: This is the switchgear that distributes power from the busbar to the power transformer. This switchgear is one of the 10kV outgoing line cabinets.
Components: Three sets of three-coil current transformers, disconnect switches, circuit breakers, switchgear, and live indicator.
Purpose: Primarily distributes electrical power, distributing the main power supply to the various branch circuit breakers and connecting and disconnecting branch power supplies to overcurrent and overload protection boxes.
Ⅴ. Busbar Interconnector
A busbar interconnector, also known as a busbar sectionalizer, is used to connect two busbar sections. It is often used in single-busbar sectionalizer and dual-busbar systems to accommodate user requirements for different operating modes or to ensure selective load shedding in the event of a fault.
Composition: disconnector, circuit breaker, current transformer, live display device
Function: Generally acts as a busbar. When two power sources are transmitting power at the same time, the connection is disconnected in the middle (two different power sources usually cannot overlap). When one of the power sources is cut off or out of power due to an accident, the connection cabinet will automatically connect to ensure the user's power supply. When the power is restored to the end that was originally out of power, the connection cabinet will automatically disconnect and be in the original standby state.
Ⅵ. Isolation Cabinet
Components: Circuit breaker, disconnect switch, earthing switch, current transformer, voltage transformer, lightning arrester, voltage display
Function: It is used to isolate the busbars at both ends or to isolate the powered equipment from the power supply equipment. It can provide operators with a visible endpoint to facilitate inspection and maintenance operations.
Functions of various components:
Circuit breakers: When a short circuit or overcurrent occurs, they quickly cut off power to prevent further damage. They can also function as general switches, distributing and controlling electrical energy. They are electrically operated.
Fuse: When the current rises abnormally high to a certain level and at a certain time, it melts, shutting off the current and protecting the circuit.
Isolating switches: Used to isolate the power supply, disconnecting high-voltage maintenance equipment from live equipment. They provide a clearly visible disconnect point. Isolating switches work in conjunction with circuit breakers to switch the circuits according to system operating requirements, thereby changing the system's wiring configuration.
Voltage transformers and current transformers: Convert high voltage or high current into a standard low voltage (100V) or a standard low current (5A or 1A, both rated values). This allows for standardization and miniaturization of measuring instruments, protective devices, and automatic control equipment. Transformers can also be used to isolate high-voltage systems to ensure human and equipment safety.
Lightning arrester: Through the action of parallel discharge gap or nonlinear resistor, it can cut the amplitude of intruding flow wave and reduce the overvoltage value of the protected equipment.
Summary
| Cabinet Type | Core Function | Analogy |
|---|---|---|
| Incoming Cabinet |
Main power inlet, central control, and central protection |
The main power switch in your home |
| Outgoing Cabinet |
Distributes power to various points of use |
Branch switches for lighting, outlets, and air conditioning |
| Busbar Interconnector |
Connects two power sources for improved reliability |
Valve connecting two water pipes, providing backup for each other |
| PT Cabinet |
Measures and provides system voltage signals |
The power grid's "blood pressure monitor" |
| Metering Cabinet |
Measuring power consumption for billing purposes |
The power grid's "water meter" |
| Isolation Cabinet | Safety isolation for easy maintenance | Upstream valve closed during water pipe maintenance |
These switch cabinets are connected together through busbars to form a complete power distribution system, which can safely, reliably and efficiently transmit electricity to every place where it is needed.
Contact Us
Electricity is the lifeblood of industry, and switchgear is the core hub that controls this flow. Choosing a safe, stable, and efficient switchgear is the cornerstone of ensuring your company's production and operations.
Shaanxi Huadian has been deeply involved in the electrical industry, specializing in the research, development, and manufacturing of high-end switchgear. We offer a full range of solutions, including:
High-voltage switchgear (such as the KYN28A-12): Provides reliable protection and intelligent control for your grid access.
Low-voltage switchgear (such as the MNS, GGD, and GCK): Accurately distributes every kilowatt-hour of power, safeguarding the safety of end-user equipment.
Intelligent complete equipment: Integrated intelligent monitoring systems enable remote operation and maintenance, power management, and support enterprise intelligent upgrades.
Our Core Strengths:
Craftsmanship: We strictly adhere to international standards, utilize high-quality components, and meticulously craft each cabinet to ensure exceptional quality.
Technological Leadership: We have an experienced R&D team and advanced production lines, enabling customized development tailored to customer needs.
Full-Lifecycle Service: We provide one-stop service, from solution consultation and design, production and installation, to commissioning and training, ensuring peace of mind.
We're your trusted partner!Contact us today to get a customized power distribution solution and quote!
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