A New Medium Power UPS using Transistor Conversion

This paper describes a new line of utility frequency UPS designed for modern data communications and processing applications. Emphasis has been given to high reliability by the use of a simple new power switching circuit which is discussed. Very high efficiency is achieved by the use of new high voltage transistor switches which are illustrated. Problems and solutions using these switches in this application are discussed. A packaging plan which conforms with international safety standards for dead front, open door operation is shown including provision for easy front only service access. A 3Ø system with static bypass and 5th generation step PWM technology is presented with high performance characteristics. Provision for handling nonlinear loads with low distortion output is illustrated. Integration of computerized "over the telephone" diagnosis for operation and maintenance providing waveforms and an audit trail to service personnel is shown.