Cabinet Enclosure: The cabinet enclosure serves as the foundation of a complete low-voltage power distribution cabinet; typically constructed from high-quality steel, it possesses sufficient structural strength and protective capabilities. It is classified into two types: enclosed and semi-enclosed. Enclosed cabinets are suitable for harsh environments, while semi-enclosed cabinets facilitate the visual inspection of internal components.
Busbars: Busbars constitute the primary conduits for electrical energy transmission. Generally fabricated from copper or aluminum bars, they exhibit excellent electrical conductivity and mechanical strength. The specifications and cross-sectional area of the busbars are selected based on the distribution cabinet's rated current and load conditions; they are typically installed at the top or rear of the cabinet enclosure.
Circuit Breakers: Circuit breakers are critical components for circuit protection, capable of automatically interrupting a circuit in the event of overload, short circuit, or undervoltage conditions. Common types of circuit breakers include air circuit breakers and molded-case circuit breakers, which are suitable for large-capacity and small-scale power distribution systems, respectively.
Contactors: Contactors are utilized to control the switching (opening and closing) of circuits, achieving the engagement and disengagement of contacts through electromagnetic force. Primarily comprising an electromagnetic system, a contact system, and an arc-extinguishing device, they are frequently employed to control the starting, stopping, and forward/reverse operation of electric motors.
Relays: Relays control the switching of output circuits in response to changes in input signals, serving functions related to signal conversion, protection, and control. Common types include intermediate relays, time relays, and thermal relays, which are used for signal amplification, timing control, and electric motor overload protection, respectively.
Fuses: Fuses are short-circuit protection devices consisting of a fusible element (fuse link) and a fuse tube. When a short circuit occurs in the circuit, the fusible element melts and severs the circuit, thereby protecting the equipment from damage. When selecting a fuse, it is essential to consider its rated current and fusing characteristics.
Current Transformers (CTs) and Voltage Transformers (PTs): These two types of transformers are used to measure current and voltage within a circuit. They step down high voltages and large currents into lower voltages and smaller currents, facilitating measurement and enabling their use with protective devices. During operation, it is critical to ensure that the secondary side of these transformers is neither left open-circuited nor short-circuited.
