The gate-turn-off thyristor: a breakthrough for the retrofit of existing induction motors from fixed to adjustable speed

Gate-turn-off (GTO) technology, application considerations, and new inverter design features are presented, and an example of drive economics is provided. Motor stresses for a retrofitted induction motor such as thermal heating, voltage stress, electrical resonance, and torsional problems are discussed. Drive control, diagnostic capability, and fiber optic gate control are given as examples of drive equipment features. One of the major advantages of GTO technology is a nearly sinusoidal output waveform for the motor. Since this new product is directed for use with existing induction motors, downtime and expense for conversion on-site to adjustable speed can be greatly reduced