Light emitting diodes are commonly used as indicator lights, which are installed on the panels, panels, tables, and cabinets of high and low voltage distribution devices, as well as on the panels of certain low-voltage electrical equipment and instruments, or in other prominent positions. The indicator light that reflects the working status of the equipment is usually red to indicate that it is in operating mode, green to indicate that it is in shutdown mode, and milky white to indicate that it is in testing mode; An indicator light that reflects the status of the device's position, usually indicating that the device is powered on and off, indicating that the device is powered off; An indicator light that reflects the working status of a circuit. Usually, a red light indicates power, while a green light indicates no power. To avoid misjudgment, it is necessary to regularly or regularly check the integrity of light bulbs or light-emitting diodes during operation.