Low-voltage electrical appliances are components or devices that can manually or automatically connect or disconnect circuits according to external signals and requirements, in order to switch, control, protect, detect, transform, and regulate circuits or non-electrical objects. Control electrical appliances can be divided into two main categories based on their operating voltage, with AC 1200V and DC 1500V as the dividing line: high-voltage control electrical appliances and low-voltage control electrical appliances. In general, low-voltage electrical appliances can be divided into two main categories: distribution electrical appliances and control electrical appliances, and they are the basic components of complete sets of electrical equipment. In industry, agriculture, transportation, national defense, and residential electricity consumption sectors, low-voltage power supply is widely used; therefore, the quality of electrical components directly affects the reliability of low-voltage power supply systems. Common examples include knife switches, fuses, low-voltage circuit breakers, contactors, relays, and control devices, etc.
Knife switch: also known as knife switch or disconnect switch, it is the simplest and most widely used low-voltage electrical appliance in manual electrical control.
A fuse, also known as a circuit breaker, is defined as a "fuse-link" in IEC 127. It is an electrical component installed in a circuit to ensure its safe operation. Fuses are widely used in high and low voltage power distribution and control systems, as well as electrical equipment, serving as protectors against short circuits and overcurrents, and are one of the most commonly used protective devices.
Low-voltage circuit breakers (formerly known as automatic switches) are switching devices that can connect and disconnect not only normal load current and overload current, but also short-circuit current. In addition to their control function, low-voltage circuit breakers also have certain protection functions in the circuit, such as overload, short circuit, undervoltage, and leakage protection.
Contactor: refers to an electrical device in industrial electricity that uses the magnetic field generated by the current flowing through a coil to close the contacts, thereby controlling the load.
A relay is an electrical control device. It has an interactive relationship between the control system (also known as the input circuit) and the controlled system (also known as the output circuit). It is commonly used in automated control circuits, and is essentially an "automatic switch" that uses a small current to control a large current. Therefore, it plays a role in automatic adjustment, safety protection, and circuit switching in circuits.
Control electrical appliances: These are switching electrical appliances used to connect and disconnect control circuits to issue commands or to perform programmed control of the production process.
