| 摘要 |
<p>PURPOSE:To rotate an electric motor in normal direction even if phase sequence is erringly connected by installing an automatic phase sequence correcting apparatus consisting of a reverse rotation preventing relay and an electromagnetic relay in an electric circuit for an electric motor for a vacuum pump. CONSTITUTION:An automatic phase sequence correcting apparatus 41 is installed in an electric cable 14 for an electric motor 12 in a vacuum apparatus. In the case where V, W phases of three phases are erringly connected, terminals (1)-(5) becomes 'off' and other terminals (5)-(8) become 'on', and an electric power is applied to an exciting coil 45A of an electromagnetic relay 45 and thus contacts of 46a, 47a become 'on' and V, W phases are exchanged and corrected automatically. Consequently, when a switch 16 is turned on, the electric motor 12 is rotated in normal direction. In this way, even if phase sequence of three phases are erringly connected, the phase sequence is automatically corrected and the electric motor is rotated in normal direction and correction of error connection becomes unnecessary.</p> |
