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 achieve switching, control, protection, detection, transformation, and regulation of circuits or non-electrical objects. Frequency converters, centrifugal fans, and speed reducers are all low-voltage electrical appliances. Specific installation and usage precautions for them are as follows:
1. Low-voltage electrical appliances should be installed in locations free from severe vibration and at an appropriate height from the ground. Power cords for knife switches, load switches, etc., must be connected to fixed contacts; it is strictly forbidden to hang power cords on knife switches.
2. Low-voltage electrical appliances should be installed vertically, especially oil-immersed reduced-voltage starters. To prevent insulating oil from overflowing the tank, the tilt should not exceed 5 degrees; they should be bolted to a support, not welded; the installation location should be convenient for operation, and the handle should be kept a certain distance from surrounding buildings to prevent damage.
3. The metal casing or metal bracket of low-voltage electrical appliances must be grounded (or connected to neutral). Exposed parts of electrical appliances should be covered with protective covers. The open position of double-throw knife switches should have a device to prevent them from closing on their own.
4. In factories with flammable or explosive gases or dust, electrical appliances should be installed outdoors in a sealed manner and with rain protection measures. Explosion-proof electrical appliances must be used in places with explosion hazards.
5. Single-pole switches must be connected to the phase line. For low-voltage electrical appliances installed on the ground, the bottom should be 100mm above the ground. The name of the installed equipment and its circuit number or circuit designation should be clearly marked on the panel where the low-voltage electrical appliance is installed.
6. Before use, remove the protective oil layer from all contact surfaces. Before putting it into operation, operate it several times to check its operation. The stationary contacts of low-voltage electrical appliances should be connected to the power supply, and the moving contacts should be connected to the load.
7. During use, the surfaces of the electrical contacts should be kept clean and smooth, ensuring good contact. The contacts should have sufficient pressure, and the action of each phase contact should be consistent. The arc-extinguishing device should be kept intact.
