Techniques are provided for protecting a rotary positive displacement pump, e.g., using a signal processor that receives signaling containing information about power, torque, speed, viscosity and specific gravity related to the operation of a pump; and determines whether to enter an enhanced pump protection mode for the rotary positive displacement pump based at least partly on a relationship between an actual corrected tune ratio and a tuned ratio set point (Tune Ratio SP). The signal processor may determine if the actual corrected tune ratio is less than or equal to the actual corrected tune ratio set point (Tune Ratio SP), and if so, then to enter the enhanced pump protection mode, else continues to use a basic pump protection mode, and also determines the actual corrected tune ratio based upon a ratio of an actual corrected power (PAcorr) divided by a tuned corrected power (PTcorr) at a specific operating speed.

The present disclosure describes a load/unload control method for a compressor system with a rotating compressor connected to a pressure vessel. In the method, the present operating state can be monitored on the basis of a monitored/estimated electrical quantity of the compressor system, The method comprises an identification phase and an operational phase. In the identification phase, the compressor is operated at a constant rotational speed to generate two known pressures to the pressure vessel. At least one electrical quantity is monitored, and values of the electrical quantity corresponding to the pressure limits are stored. In the operational phase, reaching of a pressure limit may then be detected by comparing the present value of the monitored electrical quantity to the stored values.

A compressor, a monitoring system and a method of monitoring a compressor that make it possible to monitor the remaining lifetime of a semiconductor element of a motor control system while the processing load is reduced are provided. A compressor (1) includes: a motor control system (10) that controls the rotation speed of a motor (2); a compressor body (3) that compresses air by being driven by the motor (2); a pressure sensor (20) that is provided on the discharge side of the compressor body (3); and a running controller (11) that performs switching between load running and no-load running on the basis of the pressure sensed by the pressure sensor (20). A motor controller (26) of the motor control system (10) calculates a relative temperature of a semiconductor element relative to a reference temperature by using a temperature of the semiconductor element sensed by a temperature sensor (27) at the time of switching from no-load running to load running, and calculates an amount of change in a remaining lifetime of the semiconductor element corresponding to the relative temperature of the semiconductor element, whereby monitoring the remaining lifetime of the semiconductor element.

A water pumping system, a motor drive, and a method of starting pumping by the motor drive. The method includes powering the electric motor with a motor drive; driving a progressive cavity pump with the electric motor; monitoring a speed difference between an electrical speed and an observed speed of a rotor of the electric motor; and performing a protective action as a function of the speed difference.

A water pumping system, a motor drive, and a method of starting pumping by the motor drive. The method includes performing repeated starting attempts to overcome stiction in a progressive cavity pump by attempting to supply power to an electrical motor at increasing power levels in each starting attempt and supplying the power at the increasing power levels if the power is available in from a power source; and after each starting attempt: reducing the power applied to the electrical motor to a reduced power level; determining a rotational speed of the electrical motor; determining if the rotational speed matches a speed corresponding to the reduced power level applied to the electrical motor; if the rotational speed does not match and a predetermined number of starting attempts has not been reached, performing a next starting attempt; and if the rotational speed does match, entering a normal mode of operation.

Systems and methods are used to control operation of a rotary compressor of a refrigeration system to improve efficiency by varying the volume ratio and the speed of the compressor in response to current operating and load conditions. The volume of the axial and/or radial discharge ports of the compressor can be varied to provide a volume ratio corresponding to operating conditions. In addition, permanent magnet motors and/or control of rotor tip speed can be employed for further efficiency gains.

A method for controlling the speed of a compressor with a controller as a function of the available gas flow. The method includes the steps of setting a desired value for the inlet pressure; determining the inlet pressure; and determining the speed. The method further includes controlling the speed of the compressor by reducing or increasing it depending on whether the inlet pressure is less than or greater than a set desired value until the inlet pressure is equal to the set desired value where the characteristic data of the compressor relating to the efficiency and/or the Specific Energy Requirement (SER) as a function of the speed and the inlet pressure is provided and the desired value of the inlet pressure is adjusted on the basis of the aforementioned characteristic data so that the efficiency of the compressor is a maximum or the SER is a minimum.

Systems and methods are used to control operation of a rotary compressor of a refrigeration system to improve efficiency by varying the volume ratio and the speed of the compressor in response to current operating and load conditions. The volume of the axial and/or radial discharge ports of the compressor can be varied to provide a volume ratio corresponding to operating conditions. In addition, permanent magnet motors and/or control of rotor tip speed can be employed for further efficiency gains.

Systems and methods are used to control operation of a rotary compressor of a refrigeration system to improve efficiency by varying the volume ratio and the speed of the compressor in response to current operating and load conditions. The volume of the axial and/or radial discharge ports of the compressor can be varied to provide a volume ratio corresponding to operating conditions. In addition, permanent magnet motors and/or control of rotor tip speed can be employed for further efficiency gains.

A compressor, a monitoring system and a method of monitoring a compressor that make it possible to monitor the remaining lifetime of a semiconductor element of a motor control system while the processing load is reduced are provided. A compressor (1) includes: a motor control system (10) that controls the rotation speed of a motor (2); a compressor body (3) that compresses air by being driven by the motor (2); a pressure sensor (20) that is provided on the discharge side of the compressor body (3); and a running controller (11) that performs switching between load running and no-load running on the basis of the pressure sensed by the pressure sensor (20). A motor controller (26) of the motor control system (10) calculates a relative temperature of a semiconductor element relative to a reference temperature by using a temperature of the semiconductor element sensed by a temperature sensor (27) at the time of switching from no-load running to load running, and calculates an amount of change in a remaining lifetime of the semiconductor element corresponding to the relative temperature of the semiconductor element, whereby monitoring the remaining lifetime of the semiconductor element.