The XL-21 series low-voltage power distribution cabinet is suitable for power distribution and lighting distribution in industrial and civil buildings for three-phase four wire power systems with AC frequency of 50HZ, voltage of 500V and below. Suitable for making various motor starter cabinets, including full voltage direct starter cabinets, fully digital control soft starter cabinets, autotransformer step-down starter cabinets, star delta starter cabinets, multi speed motor starter cabinets, etc. There are dozens of primary line scheme numbers or derived scheme numbers for selection and use, with a wide range of applications.