| 摘要 |
PURPOSE:To enable quick circuit breaking to be performed through the early detection of commutation failure even in high-speed range by providing a voltage relay for detecting the 0-value of commutating circuit output voltage. CONSTITUTION:An induction motor 1 is driven through the change-over of a power rectifier 3 and a power inverter 4, the outputs of the converters 3 and 4 are commutated by a commutating circuit 5, and the output of the circuit 5 is supervised by a voltage relay 7. When 0-value is detected, contactors 52M and 52G are cut off. The voltage on the DC side of the converter 4 which shows such a cut waveform as denoted by (a) in the drawing comes to show such a waveform having position crests as denoted by (b) when commutated and such a wave form as denoted by (c) on either of high and low speeds when smoothed. Commutation failure if any is detected immediately since 0-value appears in the waveform denoted by (c). Circuit breaking can be performed quickly through the early detection of commutation failure even in high-speed range. |
