WTHD medium and high power (10-120kVA) three-input, three-output power frequency double-conversion online intelligent fully digital UPS is a sine wave online highly intelligent uninterruptible power supply product that integrates digitalization, informationization and networking. It has a powerful information collection system, signal processing system and complete protection system. It is widely used in various power environments. It has good personalized design and friendly human-computer dialogue functions. It uses advanced all-digital technology to protect computers and communications. The use of electrical equipment such as instruments, electrical facilities, and medical equipment is safe and comprehensively solves various power problems such as power outages, voltage fluctuations/sudden changes, frequency changes, electronic noise, and lightning strikes. It is mainly used in industrial application protection, power supply protection of important institutions such as transportation, electric power, medical treatment, and venues, small data computer rooms/communication network management centers, office automation/experimental instruments and equipment, and other industries.