Definition and classification of low voltage electrical appliances

China's current standards refer to electrical equipment in electrical circuits with operating voltage AC 1000V and DC 1200 V below. There are many types of low-voltage electrical appliances. According to their structural uses and controlled objects, there are different classification methods. The following three classification methods are introduced:

1. According to different purposes and control objects, low-voltage electrical appliances can be divided into power distribution appliances and control appliances.

(1) Distribution electrical appliances for low-voltage power networks

Such appliances include knife switches, transfer switches, air circuit breakers and fuses. The main technical requirements for power distribution appliances are strong current interruption capability, and the current limiting effect is accurate and reliable in the event of system failure; there is sufficient thermal stability and dynamic stability.

(2) Control appliances for electric drag and automatic control systems

Such appliances include contactors, starters, and various control relays. The main technical requirements for controlling electrical appliances are high operating frequency, long life and corresponding conversion capability.

2. According to different operation modes, low-voltage electrical appliances can be divided into automatic electrical appliances and manual electrical appliances.

(1) Automatic appliances

An electric appliance that performs operations such as turning on, breaking, starting, reversing, and stopping by electromagnetic (or compressed air) is called an automatic electric appliance. Commonly used automatic appliances include contactors, relays, and the like.

(2) Manual electrical appliances

An appliance that performs work such as turning on, breaking, starting, reversing, and stopping by manpower is called a manual electric appliance. Commonly used manual appliances include knife switches, transfer switches and main electrical appliances.

3, according to the working principle can be divided into electromagnetic appliances and non-electrical control appliances

Xiao Bian will focus on the most typical types of low-voltage electrical appliances, such as knife switches, fuses, air circuit breakers, contactors, relays, main electrical appliances, starters and so on.

In addition, low-voltage electrical appliances can be divided into general industrial electrical appliances, marine electrical appliances, chemical electrical appliances, mining electrical appliances, traction electrical appliances and aviation electrical appliances according to working conditions. Protection type, moisture resistance, corrosion resistance and resistance to different types of low-voltage electrical appliances. The requirements for performance such as impact are different.

When we use water in our daily life, we need to install different valves to control and regulate the water flow in the pipeline that transports tap water and in various water sources. In the case of transmission lines that transmit electrical energy and various types of electricity, different electrical appliances are also used to control the circuit on and off, and various parameters of the circuit are adjusted. It is just that the delivery and use of electrical energy is much more complicated than the use of tap water. The purpose of the low-voltage electrical appliance in the circuit is to automatically or manually turn on and off the circuit according to external signals or requirements, continuously or intermittently change the state of the circuit, and switch, control, protect, detect and adjust the circuit.