A device is provided for pumping fluid from a wellbore up to surface. The device includes a stator unit, a rotor unit run within the stator unit on a rod string, the rotor unit and the stator unit engaging with one another to form an annular space therebetween for passage of fluid. An upstream check valve on the rod string uphole of the rotor unit is moveable from an open position in which fluid is passable through the annular space, and a closed position in which fluid passage through the annular space is prevented. A hollow rod section extends through the rod string in fluid communication with the annular space both downstream and upstream of the upstream check valve, for entry of fluid into a downhole end of the hollow rod section, passage of fluid upstream therefrom and exit of fluids from an uphole end of the hollow rod section, back into the annular space. A method is further provided for pumping fluid from a wellbore after shutdown.

A method for controlling a permanent magnet (PM) synchronous motor in an ESP application is provided. A load angle of the PM motor is estimated. A voltage adjustment value is determined for the PM motor based at least on the estimated load angle of the PM motor. A voltage to be applied to the PM motor is determined based on the voltage adjustment value.

A method for controlling a permanent magnet (PM) synchronous motor in an ESP application is provided. A load angle of the PM motor is estimated. A voltage adjustment value is determined for the PM motor based at least on the estimated load angle of the PM motor. A voltage to be applied to the PM motor is determined based on the voltage adjustment value.

Systems and methods for a compressor system are provided for selectively operating the compressor system with reduced power consumption. An output demand level of the compressor system can be monitored over time to identify a demand profile. A pressure setpoint for the compressor system can be selectively adjusted based on the demand profile, including to selectively transition between an operational pressure setpoint for an active demand profile and a reduced pressure setpoint for an inactive demand profile.

Systems and methods for a compressor system are provided for selectively operating the compressor system with reduced power consumption. An output demand level of the compressor system can be monitored over time to identify a demand profile. A pressure setpoint for the compressor system can be selectively adjusted based on the demand profile, including to selectively transition between an operational pressure setpoint for an active demand profile and a reduced pressure setpoint for an inactive demand profile.

A fault-rectification method for an eccentric screw pump of a conveying apparatus for conveying viscous construction materials, comprising the steps of monitoring a start of a conveying operation of the eccentric screw pump by way of a characteristic-variable-monitoring program of a control device of the conveying apparatus, wherein a working-free program is executed by the control device of the eccentric screw pump if, for one or more characteristic variables. The characteristic-variable-monitoring program acquires characteristic-variable values which are stored, alone or in combination with one another, as fault values that indicate jamming of a rotor/stator unit of the eccentric screw pump, and wherein otherwise a conveying operation is begun. The eccentric screw pump is operated in the working-free program in such a way that an electric motor of a drive unit of the conveying apparatus is multiply alternately switched on and switched off.

A fault-rectification method for an eccentric screw pump of a conveying apparatus for conveying viscous construction materials, comprising the steps of monitoring a start of a conveying operation of the eccentric screw pump by way of a characteristic-variable-monitoring program of a control device of the conveying apparatus, wherein a working-free program is executed by the control device of the eccentric screw pump if, for one or more characteristic variables. The characteristic-variable-monitoring program acquires characteristic-variable values which are stored, alone or in combination with one another, as fault values that indicate jamming of a rotor/stator unit of the eccentric screw pump, and wherein otherwise a conveying operation is begun. The eccentric screw pump is operated in the working-free program in such a way that an electric motor of a drive unit of the conveying apparatus is multiply alternately switched on and switched off.

A vane pump (101) for an automatic transmission includes a suction-side behind-vane pressure duct (112) and a pressure-side behind-vane pressure duct (111). The suction-side behind-vane pressure duct (112) is connected to the pressure side (116) of the vane pump (1). A valve device (113, 114) is connected to the pressure-side behind-vane pressure duct (111). During operation of the vane pump (101), a pressure-side behind-vane pressure (p DH) can be set in the pressure-side behind-vane pressure duct (111) with the valve device (113, 114).

A vane pump (101) for an automatic transmission includes a suction-side behind-vane pressure duct (112) and a pressure-side behind-vane pressure duct (111). The suction-side behind-vane pressure duct (112) is connected to the pressure side (116) of the vane pump (1). A valve device (113, 114) is connected to the pressure-side behind-vane pressure duct (111). During operation of the vane pump (101), a pressure-side behind-vane pressure (p DH) can be set in the pressure-side behind-vane pressure duct (111) with the valve device (113, 114).

A priming pump may include a housing; an inlet passageway inside of the housing; an outlet passageway inside of the housing; a divider, inside of the housing, separating the inlet passageway and the outlet passageway; a connecting passageway through the divider in fluid communication with the inlet passageway and the outlet passageway; a valve, disposed in the connecting passageway, configured for one-way fluid flow from the inlet passageway to the outlet passageway; a rotary pump, inside of the housing, having an inlet in fluid communication with the inlet passageway and an outlet in fluid communication with the outlet passageway; and a shaft connected to the rotary pump and extending through the housing, the shaft configured for rotation by an external driving mechanism.