Introduction to the medium voltage chamber cabinet in the power system
Medium voltage inlet isolation cabinet.
In the high-voltage distribution wiring, there should be a clear disconnection point between the power switch and the power supply, which can ensure that the power supply can be seen to be disconnected during maintenance to ensure personal safety, so an isolation cabinet is often set up in front of the high-voltage incoming cabinet to ensure that the high-voltage cabinet is disconnected from the power supply.
The main components of the medium voltage inlet isolation cabinet include:
Inlet switch: The inlet switch is used to control the connection and cut-off of the medium voltage power supply. It typically has isolation and disconnect functions to isolate the power supply from the system and allow maintenance and servicing of the incoming power supply.
Instrumentation and protection devices: Incoming isolation cabinets are usually equipped with a variety of meters and protection devices to monitor and protect the power system. These include measuring instruments for current, voltage, frequency, power factor and other parameters, as well as overcurrent protection, short circuit protection, grounding protection and other devices to ensure the safe operation of the system.
Grounding switch: The grounding switch is used to connect or cut off the grounding loop of the incoming isolation cabinet. It is often used to protect personnel and equipment from electrical faults and ensure the grounding safety of the system.
Control system: The medium voltage inlet isolation cabinet may be equipped with a control system for remote control and monitoring of the operation of the equipment. These control systems can increase the degree of automation of equipment and provide real-time monitoring and fault diagnosis of system status.
2.Medium voltage inlet cabinet.
1. It mainly plays the function of circuit relay protection between the power grid and the user.
2. It is used to protect the user's power supply lines and electrical equipment, and a kind of local protection in the event of an accident on the road or equipment, which can take the accident equipment or line off the power grid in time.
3.Medium voltage metering cabinet.
The cabinet where a special meter is installed is called a metering cabinet and is generally managed by the power department. The metering cabinet is generally called the electric energy metering cabinet, including the equipment.
1.A current transformer (CT) that provides a current signal to the watt-hour meter.
2.Voltage transformer (PT), which provides a voltage signal to the watt-hour meter.
3.High-voltage fuses to provide overcurrent protection for voltage transformers.
4.Three-wire three-phase watt-hour meter to measure electrical energy.
4.Medium pressure diesel engine inlet cabinet.
The function is similar to that of the incoming cabinet, as the input cabinet of the diesel power supply, it forms a standby relationship with the mains through the electrical interlock, and has the protection function at the same time.
The main functions of the medium pressure diesel engine inlet cabinet include:
Inlet switch: The inlet switch is used to control the connection and cut-off of the diesel generator. It is usually circuit-open and isolated, and is used to safely connect or cut off power from the generator and switch it to the power system.
Protection and control devices: Diesel engine inlet cabinets are usually equipped with protection and control devices to monitor and protect generators and power systems. These include overcurrent protection, short-circuit protection, frequency protection, voltage protection and other devices to ensure the safe operation of equipment and systems.
Automatic switching device: The medium voltage diesel engine inlet cabinet usually has an automatic switching device, which is used to automatically switch the diesel generator to the backup power supply and achieve a smooth transition when the power system is interrupted or power failure.
Control system: The diesel engine inlet cabinet may be equipped with a control system for remote control and monitoring of incoming switches, generators and related equipment. The control system can improve the automation of equipment and provide real-time monitoring and fault diagnosis of system status.
5.Medium voltage bus PT cabinet.
Chinese name: voltage transformer cabinet, generally installed directly on the busbar to detect the busbar voltage and realize the protection function. What it does:
1.Voltage measurement, which provides the loop voltage of the meter.
2.Operating and control power is available.
3.The installation of overvoltage protectors for each section of bus.
4.The need for relay protection, such as bus insulation, overvoltage, undervoltage, standby self-investment conditions, etc.
6.Medium voltage feeder cabinet.
Another name: wiring cabinet, output cabinet, the so-called feeder cabinet, is the cabinet through the power distribution device to feed out (distribute) electric energy to different loads.
It is a bus that can be strong or weak current into the line and then distributed to each terminal, in enterprises, industrial and mining enterprises, shopping malls, entertainment places due to the large capacity, can be called "feeder cabinet", home places called feeder box, popular name (distribution box).
7.Lifting cabinets.
The lifting cabinet refers to the need to go from the bottom to the top of the busbar in the cabinet, and the second section of the bus bar will be led from the top to the bottom when it passes through the bus unit, so that the bus bar needs to be led from the bottom to the top, and a bus lifting cabinet is used in the design.
8.Medium voltage contact cabinet.
The contact cabinet refers to the power distribution cabinet responsible for connecting or disconnecting the two sections of bus.
Function: Realize the interconnection function of the two circuits to ensure the reliability of power supply and emergency power supply.
It usually consists of the following main components:
Busbar: A busbar is a conductive metal rod or wire used to transport medium-voltage electrical energy from a generator or transformer to various electrical load points. The busbar in the medium-voltage liaison cabinet is used to connect the power supply and load equipment and to provide power distribution.
Contact switch: The contact switch is used to control the connection and disconnection of the medium voltage power supply and the main bus of the system. It is usually a switchgear with a circuit break and isolation function, which is used to realize the contact and switching of the power supply.
9.DC screen.
It provides DC power supply for high-voltage cabinet energy storage circuits, control circuits, etc., and AC power supply for PLC cabinets. The working principle is similar to that of UPS, which contains a battery, which can ensure that the circuit breaker can be opened and closed normally in the AC power-off state.
10.Self-invested PLC control cabinet.
The standby power automatic input device can automatically switch the contact cabinet or diesel-generated power supply after the mains power failure, but the diesel-generated power supply needs to be manually switched when switching to the mains.
It usually consists of the following main components:
PLC controller: The PLC controller is the core component of the standby self-throwing control cabinet, which is used to monitor and control the power switching process. It controls the power switching device (such as circuit breaker, contactor, etc.) according to the preset logic and conditions to achieve automatic switching and priority control.
Power switching device: The power switching device is used to switch between the main power supply and the standby power supply.
Common switching devices include circuit breakers, contactors, or automatic transfer switches, which ensure that loads can be quickly and reliably connected to the backup power supply in the event of a mains power failure.