Abstract: A pumping system has a motor (32) for driving a pumping mechanism (30). A variable frequency drive unit (36) has an input for receiving electrical energy of relatively high power and first, fixed frequency from a power supply, and an output coupled to an input (46) of the motor for supplying electrical energy of relatively low power and second, variable frequency to the motor. This second frequency preferably has a maximum value greater than the first frequency. A control circuit (50) is provided for selectively coupling the motor input (46) directly to the power supply for the supply of the relatively high power energy to the motor to maximize the torque that can be produced by the pumping mechanism. After a period of time the control circuit terminates the direct coupling of the motor input to the power supply for the supply of the relatively low power energy to the motor.

Abstract: The present invention provides a pumping system (60) comprising: a pumping mechanism (64); a motor (51) for driving the pumping mechanism; a drive control (50) for controlling the motor; and means (52) for monitoring at least one state within the system; wherein, to improve the performance of the system, the drive control causes the system to operate for transient periods in an overload condition which can result in said monitored state exceeding a predetermined operational limit, and when operating in said overload condition said drive control controls the power to the motor dependent on the level of said monitored state thereby avoiding said state from exceeding said operational limit.

Abstract: A vacuum pump includes a rotor assembly mounted on a driven shaft, and a motor for rotating a drive shaft in forward and reverse directions. A drive member on the drive shaft engages a driven member on the driven shaft. Each member has first and second impact surfaces. The members are configured to permit at least one quarter of a revolution of the drive member relative to the driven member in either the forward or the reverse direction before one of the impact surfaces of the drive member impacts upon a corresponding impact surface of the driven member. This enables the drive member to acquire sufficient angular momentum before it impacts the driven member such that the amount of energy transferred to the driven shaft upon impact can be sufficient to free a pump that has become locked by process deposits.

Abstract: A pumping system has a motor (32) for driving a pumping mechanism (30). A variable frequency drive unit (36) has an input for receiving electrical energy of relatively high power and first, fixed frequency from a power supply, and an output coupled to an input (46) of the motor for supplying electrical energy of relatively low power and second, variable frequency to the motor. This second frequency preferably has a maximum value greater than the first frequency. A control circuit (50) is provided for selectively coupling the motor input (46) directly to the power supply for the supply of said relatively high power energy to the motor to maximise the torque that can be produced by the pumping mechanism. After a period of time the control circuit terminates the direct coupling of the motor input to the power supply for the supply of said relatively low power energy to the motor.