| 摘要 |
<p>PURPOSE:To shorten an operation time for speed detection by providing two rotating speed detectors or more and selecting only one output of a sound detector according as each detector is out of order or not. CONSTITUTION:In a system for collectively controlling three units of three-phase induction motor by one variable voltage and variable frequency inverter, second and third shafts are provided with motor rotating speed detection pulse generators PG1, PG2. Then, output pulses of said pulse generators PG1, PG2 are compared with each other. If one pulse generator PG1 or PG2 is out of order, the output of another sound pulse generator PG2 or PG1 is selected. An output of pulse generator PG1 or PG2 equipped with a shaft hard to slip or skid is selected, if both pulse generators PG1, PG2 are sound. This enables shortening an operation time for speed detection.</p> |
