| 摘要 |
<P>PROBLEM TO BE SOLVED: To efficiently exhaust gas, by restraining electric power consumption in the most upstream side sub-pump in a vacuum pump device whose sub-pump exists on the upstream side of a main pump in an exhaust passage. Ž<P>SOLUTION: The inside of a load lock chamber 36 is put in a desired low pressure state (a vacuum state) by operation of a booster pump 27 (the sub-pump) and the main pump 10. An inverter 38 is electrically connected to an electric motor M1 of the main pump 10, and an inverter 39 is electrically connected to an electric motor M2 of the booster pump 27 via an electromagnetic circuit breaker 40. A rotating speed detector 43 is connected to a control device 41 by a signal. The rotating speed detector 43 detects a rotating speed of the electric motor M2 of the booster pump 27. When the rotating speed of the electric motor M2 becomes a reference rotating speed No or less, the control device 41 temporarily cuts off the electromagnetic circuit breaker 40. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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