Medium Voltage Switchgear

1. Introduction to Medium Voltage Switchgear

Medium voltage switchgear is a crucial electrical device in industrial electrical construction projects. It is used to switch and protect medium voltage power supply lines. Currently, medium voltage switchgear is designed and manufactured following strict quality management processes, ensuring high stability and safety during operation.

2. Operating Principle of Medium Voltage Switchgear

Let’s study a basic schematic of medium voltage switchgear as shown below:

The MV power source diagram is commonly found in many buildings or factories. At this point, electricity is supplied from the 22kV power grid. Typically, power is drawn from the grid through a series of Ring Main Unit (RMU) switchgears. However, this article will bypass that part and direct the power into branch 1 down to the factory and then distribute it to subsequent branches.

In theory, electricity is transmitted via conductors, but in practice, it is arranged in a series of cabinets. This means you have to connect these enclosures instead of using regular cables. For this, we should use copper partitions and attach them to the cabinet frame to enhance control capabilities, ensuring stable separation and better control of events. One important component of the cabinet is the busbar, a horizontal bar, with each branch being vertical busbars.

3. Functions of Medium Voltage Switchgear

Medium voltage switchgear is used to switch and protect medium voltage power supply lines. It is widely used in power stations, power distribution stations of power companies, industrial zones, residential areas, and commercial and residential factories.

4. Structure of Medium Voltage Switchgear

Currently, medium voltage switchgear is made from high-standard materials, applying the most stringent standards of customers.

Medium voltage switchgear can be designed simply and compactly and conveniently. Depending on usage needs, the size of the cabinet should be chosen appropriately to meet requirements while ensuring aesthetic appeal and maximizing space savings in densely populated areas and installation costs.

To ensure the safety and efficiency of the entire system, medium voltage switchgear is made from the best materials and meets strict technical criteria. The structure of medium voltage switchgear includes many components, each performing specific tasks.

4.1. Medium Voltage Cabinet Shell

The shell is made of about 2mm thick sheet metal, with a highly safe and robust insulation coating.

4.2. Switching Devices

The electrical switching devices are placed independently, logically, and protected by an inner door of the cabinet.

The cabinet includes devices such as electrical panels up to 24KV, used in the power industry or in industrial plants, and commercial buildings. For medium voltage switchgear in power stations, components include: busbar chambers, circuit breaker chambers, cable termination chambers, low voltage chambers, etc.

Note: A minimum medium voltage switchgear must contain a main circuit breaker with on/off buttons, with a capacity equivalent to or greater than three times the total sub-loads below. And a 220V socket for use during cabinet maintenance.

5. The Role of Medium Voltage Switchgear in the Electrical System

Used for medium voltage motors, transformers, and capacitor banks.
Divided into separate compartments to ensure continuous operation of each compartment.
Machine operation is only performed when the cabinet door is closed to ensure proper procedure and user safety.
Can be combined with fuses to increase the level of protection.
Modular and standardized, making installation and maintenance convenient.
Capable of remote monitoring and control.

6. Types of Medium Voltage Switchgear

To suit various purposes and terrains, this type of electrical equipment is classified into several types of medium voltage switchgear, including:

Medium Voltage Cabinets: VCB, LBS, DS.
RMU Cabinets.
Medium Voltage ATS Cabinets.
Medium Voltage Capacitor Banks.
Secondary Cabinets.

7. General Installation Process of Medium Voltage Switchgear

When installing medium voltage switchgear, you need to understand the diagram and principles of the medium voltage RMU system to be installed.

Carefully read the medium voltage switchgear schematic to understand the secondary wiring diagram and the necessary protective and measuring devices for installation.
Studying the installation and operation manual from the manufacturer is also a crucial step to grasp the manufacturer’s concept.
Before installation, prepare all necessary accessories for the cabinet such as cable connectors, power cables, backup power sources, supporting devices, and appropriate hand tools.
During installation, follow the steps in the installation and operation manual. Use appropriate hand tools for the type of medium voltage switchgear being installed.

8. Some Notes When Installing Medium Voltage Switchgear

To install a medium voltage switchgear system, the following tasks are needed:

First, create an accurate block diagram.
Survey the market to understand material prices, find materials meeting the block’s requirements, ensuring correct sizes and positions on the panel.
Prepare all necessary auxiliary materials for the switchgear, such as electrical terminals, timers, number rings, iron bars for mounting electrical devices, etc.
Proceed with installation as needed, you can prepare a plywood, fiberglass, or iron panel, and mount the components on the panel.
Review the system: check the electrical safety of the panel with the components installed on it. It must strictly follow the initial design process.
Test the system by connecting it in series with a 300W bulb. Then re-test with another load and install all other components in the cabinet.
Pull wires from the motors to the medium voltage switchgear, pull the grid power, and make the frame for the cabinet legs. Choose the grounding wire appropriately, meeting standards and safety. The cabinet’s grounding wire must be of the same type, flexible, flat, and braided.

9. Testing Medium Voltage Switchgear

Testing medium voltage switchgear during the production process is a mandatory step, following stringent requirements in current electrical testing regulations, and is a standard process implemented by Vintec Group for all products before they are shipped to customers. Medium voltage switchgear is a very important part of the industrial electrical system. Therefore, it must be thoroughly and strictly tested before being put into operation. This is an indispensable step because if the machine fails or malfunctions, the entire electrical system will be severely affected. Vintec Group has invested in a transformer testing laboratory with a synchronized modern equipment system from HAEFELY, Switzerland, ensuring absolute accuracy in testing.

10. Where to Buy Quality Medium Voltage Switchboard?

Currently, the market has many suppliers of medium voltage switchboard from various brands. However, to ensure safety for projects and human life, product quality must be the top priority. Therefore, customers need to find reputable and quality medium voltage switchgear suppliers. If you are unsure where to buy genuine medium voltage switchgear at a reasonable price, come to Vintec Group. With many years of experience in manufacturing medium voltage switchgear, low voltage switchgear, substations, and transformers, we are committed to providing customers with quality products at reasonable prices.

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