Trusted Low Voltage Switchgear Manufacturer

What Is A Low-voltage Switchgear?

A low-voltage switchgear generally refers to distribution equipment used in power systems with AC voltages up to 1000V. Its main function is to transfer electrical energy from a transformer to various end-use devices, such as lighting fixtures, motors, and control systems.In China’s commonly used 50Hz AC distribution systems, the rated voltage of low-voltage distribution cabinets is typically 380V, with rated currents reaching up to several thousand amperes.

To put it simply, if the entire power system is compared to the human blood circulation system, then a power plant is the heart, high-voltage transmission lines are the arteries, and low-voltage distribution cabinets are the capillaries reaching every end user. They are responsible for distributing the stepped‑down power reasonably to each electrical unit, ensuring that various electrical equipment – lighting, motors, etc. – can receive the required electrical energy safely and stably.Our switchgears meet the relevant national and international standards IEC 61439 and GB/T 7251 .

What are the Main Functions and Roles ？

The core functions of a low-voltage distribution cabinet can be summarized as three tasks: receiving, distributing, and protecting.

First, it receives electrical energy from the upstream power grid (for example, the low‑voltage side of a transformer) through the incoming cabinet (receiving cabinet). Then, it distributes the energy to branch circuits via the main busbar (copper bar system), and through the outgoing cabinets delivers it to equipment such as motors and lighting systems. Throughout this process, protection devices – circuit breakers, fuses, disconnectors, etc. – continuously monitor the circuit status. In the event of overload, short circuit, or leakage, they can quickly disconnect the faulty circuit, effectively protecting both equipment and personnel.

In addition, low‑voltage distribution cabinets also serve reactive power compensation. Capacitor banks (compensation cabinets) improve the power factor of the grid by automatically switching capacitor banks, reducing line losses and increasing energy efficiency.

Common Types and Models Of Low-voltage Switchgears

Based on their mounting methods, low-voltage switchgear is generally divided into two structural types: fixed-type low-voltage switchgear and drawout-type low-voltage switchgear.

Fixed-type switchgear, such as the GGD switchgear, features a fixed-panel structure with all electrical components permanently mounted in place. It is characterized by a robust structure, lower cost, and easy maintenance. It is suitable for distribution systems in power plants, substations, and industrial and mining enterprises with rated currents up to 3150A. The enclosure uses natural ventilation for heat dissipation, with ventilation slots at the top and bottom forming a natural airflow path.

Drawout-type switchgear (also called drawer-type switchgear) is represented by models such as GCK, GCS, and MNS. Its distinctive feature is that each outgoing unit is designed as an independent drawer. Drawout switchgear is more space-saving, easier to maintain, and provides more outgoing circuits, although it is generally more expensive. When a fault occurs in one circuit, only the corresponding drawer needs to be pulled out for repair, and a spare unit can be replaced without interrupting the power supply, leaving other circuits unaffected. The MNS low-voltage switchgear is manufactured based on technology transferred from ABB (Switzerland) and offers advantages such as compact design, strong structural versatility, and a high degree of modularity.

What Are the Internal Core Components in Low-voltage Switchgear?

A complete low-voltage switchgear system usually includes the following components:

Enclosure:

The enclosure is usually made of high-quality cold-rolled steel plate or stainless steel, formed through bending, welding, and powder coating. It provides mechanical support and protection.

Busbar System:

The busbar system of the low-voltage switchgear includes main busbars and branch busbars. The main busbar runs through the entire low-voltage distribution panel and is responsible for collecting and distributing the total current, while the branch busbars supply power to each output unit.

Switchgear:

The core internal components of this product include circuit breakers, disconnect switches, contactors, etc., used for control and protection. The circuit breaker is the core component, combining circuit switching and fault protection functions.

Protection Devices:

The protection devices in the cabinet usually include thermal overload relays, fuses, and residual current devices, providing multiple protections against overload, short circuit, and leakage.

Measuring and Indicating Devices:

The measuring compartments include ammeters, voltmeters, power factor controllers, indicator lights, etc., for real-time monitoring of system status.

Compensation Equipment:

These components generally include capacitor banks and their switching control units, which are used for reactive power compensation.

The technical parameters

How to Choose the suitable low-voltage switchgear?

We call the selection method the “five-step” selection method:

Step 1: Define the core electrical parameters

The basis of selection for the low-voltage switchgear is to confirm the technical parameters that the switchboard must meet according to the client's technical requirements. First, confirm the system’s rated voltage (typically AC 380V/400V, 50Hz) and rated current. The rated current should be calculated based on the total load of all electrical equipment, with a 15%–20% margin reserved for future expansion. Second, the short-circuit withstand capability is  also a critical safety indicator.The switchboard’s rated short-time withstand current (Icw) and rated peak withstand current (Ipk) must be greater than the maximum prospective short-circuit current that may occur in the system; otherwise, an explosion or fire could happen under fault conditions.

Step 2: Analyze the service environment

Environmental conditions directly affect the protection requirements and service life of the low-voltage switchgears,we need to adapt different protection grade based on the operating environment of the low-voltage switchgears.

Step 3: Match load types and functional requirements

Different loads require low-voltage switchgear to have different control and protection functions. For inductive loads such as motors (e.g., fans and pumps in factories), the starting current can reach 5–7 times the rated value. Circuits should be selected with overload, phase loss, and locked‑rotor protection, along with suitable contactors and thermal relays. For resistive loads like lighting, fixed‑type low-voltage switchgears with a simple structure and high cost‑performance are appropriate. For data centers, hospitals, and other places with extremely high requirements for power supply continuity, hot‑swappable drawout (withdrawable) low-voltage switchgear should be used, equipped with automatic transfer switches (ATS) and redundant design. Smart buildings or modern factories are better served by intelligent switchgears that support smart meters and remote monitoring and control, enabling connection to power management systems.

Step 4: Evaluate future operation, maintenance and expansion

The selection should leave sufficient room for long-term operation and future retrofits. If the ability to replace modules quickly without power interruption during a fault is desired, withdrawable (drawout) low-voltage switchgear should be preferred, as their drawer units can be independently plugged in and out. At the same time, it is advisable to reserve about 20% spare outgoing circuits based on the total number of circuits, to accommodate future equipment additions. If the budget permits and on‑site space is tight, the withdrawable type low-voltage switchgear is also a better choice. For applications requiring remote data acquisition, fault prediction, and condition‑based maintenance, intelligent drawout switchgears with communication gateways and monitoring software should be configured. Furthermore, the availability of spare parts and the after‑sales service response capability of the supplier must be considered.

Step 5: Balance the life‑cycle cost

The selection decision should not look only at the initial purchase price, but should evaluate the life‑cycle cost (LCC), including procurement, installation, operation, maintenance, downtime losses, and energy costs. Domestic brands (e.g., Chint, Delixi, Changshu Switchgear) have strong price competitiveness – the cost of key components is often 1/2 to 1/5 of that of international brands – and offer fast service response, making them suitable for projects where cost‑performance is paramount. International brands (ABB, Schneider Electric, Siemens) lead in technical specifications, have longer mean time between failures, and possess mature digital ecosystems, making them ideal for critical projects with very high reliability requirements. Blindly pursuing low prices may lead to the use of inferior sheet metal, reduced short‑circuit capacity, or simplified protection functions, resulting in frequent faults later and ultimately greater economic losses. Therefore, the optimal cost‑effective solution should be chosen while meeting safety and performance requirements.