Definition of Low-Voltage Switchgear

Low-voltage electrical equipment generally refers to electrical devices operating in circuits with an alternating voltage of 1000V or less, or a direct current of 1500V or less. Low-voltage electrical equipment is widely used in power generation, transmission, distribution, and electrical drive and automation control systems. It plays a role in the conversion, control, protection, and regulation of electrical energy production, transmission, distribution, and application.

Classification and Uses of Low-Voltage Electrical Equipment

Distribution Electrical Equipment

1.Circuit Breakers

Main Types:Air circuit breaker; Molded Case Circuit breaker; Current-limiting circuit breaker; DC fast circuit breaker; Magnetic blowout circuit breaker; Residual current protective circuit breaker

Uses: Used for overload, short circuit, or voltage protection in AC and DC circuits. It prevents frequent opening or closing of circuits. For example, magnetic circuit breakers protect generator excitation circuits, and residual current breakers are used for personal electric shock protection.

2.Fuses

Main Types: Fuse with filler in a sealed tube; Fuse for semiconductor protection; Fuse without filler in a sealed tube; Self-resetting fuse

Uses: Used for short-circuit and overload protection in AC and DC circuits and equipment.

3.Disconnect Switches

Main Types: Fused Disconnect switch;High-current Disconnect switch; Load switch

Uses: Used to isolate circuits and connect or disconnect circuits under rated current.

4.Changeover Switches

Main Types: Combination switch; Reversing switch

Uses: Used for switching between two or more power sources or loads and controlling the on/off state of circuits.

Control Electrical Equipment

1.Contactors

Main Types: AC contactor; DC contactor; Vacuum contactor; Semiconductor contactor

Uses: Used for remotely and frequently starting or controlling AC and DC motors and connecting/disconnecting the main circuit and control circuit under normal working conditions.

2.Relays

Main Types: Current relay; Voltage relay; Time relay; Intermediate relay; Thermal overload relay; Temperature relay

Uses: Used in control systems to control other electrical devices or provide protection for the main circuit.

3.Starters

Main Types: Electromagnetic starter; Manual starter; Agricultural starter; Autotransformer starter

Uses: Used for starting or controlling the forward and reverse rotation of AC motors.

4.Controllers

Main Types: Cam controller; Plain controller

Uses: Used in electrical control systems to switch circuits or excitation circuits for motor starting, reversing, and speed control.

5.Main Switches

Main Types: Button; Limit switch; Micro switch; Universal changeover switch

Uses: Used to connect or disconnect control circuits and issue commands or used for program control.

6.Resistors

Main Types: Iron-based alloy resistors

Uses: Used to change circuit parameters or convert electrical energy into heat energy.

7.Rheostats

Main Types: Excitation rheostat; Starting rheostat; Frequency-sensitive rheostat

Uses: Used for voltage regulation of generators and smooth starting and speed control of motors.

8.Electromagnets

Main Types: Lifting electromagnets; Traction electromagnets; Braking electromagnets

Uses: Used in lifting operations or for mechanical traction.