VACUUM PUMPING SYSTEMS

摘要

The present invention relates to a vacuum pumping system (10) which comprises: a vacuum pumping mechanism (12) and a motor (14) for driving the vacuum pumping mechanism. Means (16) are provided for determining a cumulative load on the vacuum pumping system over time by monitoring a characteristic of the motor over that time. Means (18) are also provided for activating a maintenance activity on the system when the cumulative load exceeds a predetermined amount.