Diagnostic system to determine the in-service life of dry vacuum pumps

A diagnostic system for dry pumps is proposed. It predicts future pump moto r current fi om time-series in-situ measurements. The prediction system has been constructed using a data acquisition system with an online system ide ntification software algorithm. A field test on a low pressure chemical vap our deposition (LPCVD) system for the silicon nitride process predicted lar ge values of motor current, some of which correlated well with actual motel currents as the pump became clogged. The combined use of the predicted mot or current and the stability criteria shows promise in predicting the actua l service life of a dry pump.