A vacuum system comprises, as an integral assembly, a vacuum pump with drive
motor,
a purge valve, a roughing valve and an electronic control module. A cryogenic vacuum
pump and a turbomolecular vacuum pump are disclosed. The control module has a programmed
processor for controlling the motor and valves and is user programmable for establishing
specific control sequences. The integral electronic control module is removable
from the assembly and is connected to the other devices through a common connector
assembly. In the turbomolecular pump system proper introduction of a purge gas
through the purge valve is detected by detecting the current load on the pump drive
or by detecting foreline pressure. To test the purge gas status, the purge valve
may be closed and then opened as drive current or pressure is monitored. After
power failure, the controller will continue normal drive of the turbomolecular
pump so long as the speed of the pump has remained above a threshold value. Otherwise
the vent valve will have been opened, and a start-up sequence must be initiated.
During shutdown, power to the pump drive motor is discontinued and the vent valve
is opened before the roughing valve is closed.
