Abstract: The invention relates to a method for monitoring and controlling the operation of a pump station (1) comprising a tank (8) for storage of a liquid and at least one pump (2), the pump station (1) further comprises an outlet conduit (5) connected to the pump (2), the method comprising the steps of: determining the Geodetic head (Hgeo) of the pump station (1), determining the pumped Flow (Q) for a given pump operation duty point, determining the consumed Power (P) for the given pump operation duty point, and determining a Normalized Specific Energy (nSE) of the pump station (1) based on the determined values of Geodetic head (Hgeo), pumped Flow (Q) and consumed Power (P), by means of the formula (nSE)=(P/Q)/Hgeo.

Abstract: A treatment plant and method for controlling a treatment plant suitable for treatment of wastewater. The treatment plant includes a circulation channel housing liquid, a submersible flow generating machine arranged in the circulation channel and generating a liquid flow along the circulation channel, and a control unit that is operatively connected to the flow generating machine. The flow generating machine is driven in operation by the control unit. The method includes the steps of: driving the flow generating machine at a nominal speed, decreasing the rotational speed of the flow generating machine from the set nominal speed, detecting the rotational speed at which the torque of the flow generating machine is equal to a predetermined threshold, and determining the flow velocity of the liquid at the flow generating machine based on a predetermined relationship between the rotational speed of the flow generating machine and the flow velocity of the liquid.

Abstract: A treatment plant and method for controlling a treatment plant suitable for treatment of wastewater. The treatment plant includes a circulation channel housing liquid, a submersible flow generating machine arranged in the circulation channel and generating a liquid flow along the circulation channel, and a control unit that is operatively connected to the flow generating machine. The flow generating machine is driven in operation by the control unit. The method includes the steps of: driving the flow generating machine at a nominal speed, decreasing the rotational speed of the flow generating machine from the set nominal speed, detecting the rotational speed at which the torque of the flow generating machine is equal to a predetermined threshold, and determining the flow velocity of the liquid at the flow generating machine based on a predetermined relationship between the rotational speed of the flow generating machine and the flow velocity of the liquid.

Abstract: A pump station arrangement and a method for turning off a pump configured for pumping liquid via a conduit. The pump, before being turned off, being driven at an operational frequency (FN) by a control unit. The method is characterized by the steps of, ramping down the frequency of the pump due to a turn off instruction, the terminal frequency of the ramping down being equal to the operational frequency (FN) of the pump minus at least 10 Hz and the ramping down time being at least a reflection time (TR) for the conduit in question, and the terminal frequency of the ramping down not being less than 10 Hz, and stopping the pump after the ramping down.

Abstract: A pump station arrangement and a method for turning off a pump configured for pumping liquid via a conduit. The pump, before being turned off, being driven at an operational frequency (FN) by a control unit. The method is characterized by the steps of, ramping down the frequency of the pump due to a turn off instruction, the terminal frequency of the ramping down being equal to the operational frequency (FN) of the pump minus at least 10 Hz and the ramping down time being at least a reflection time (TR) for the conduit in question, and the terminal frequency of the ramping down not being less than 10 Hz, and stopping the pump after the ramping down.

Abstract: A sensor for determining level of liquid in a reservoir, a reservoir containing such sensor, and a method for determining level using such sensor. The sensor comprises a liquid-proof housing, at least one actuator operatively connected to the inner side of the housing and configured to generate vibrations, and at least one vibration sensor operatively connected town inner side of the housing and configured to measure vibrations. The actuator comprises an electromagnet directly or indirectly fixedly connected to the inner side of the housing, and a permanent magnet movably suspended in the housing, wherein the electromagnet and the permanent magnet are configured such that activation of the actuator creates an oscillating mutual displacement in parallel with a longitudinal center axis of the electromagnet.

Abstract: A method for controlling at least a part of a pump station including a number of speed controlled pumps, the method is arranged to minimize the specific energy consumption Espec of at least a part of the pump station and includes a sub method, which in turn includes the steps of: obtaining input data, determining the mutual relative relationships between a first value A1 of a quantity corresponding to a first pump speed V1 and a second value A2 of the quantity corresponding to a second pump speed V2, and between a first specific energy consumption Espec1 and a second specific energy consumption Espec2, and determining a third value A3 of the quantity corresponding to a third pump speed V3.

Abstract: A sensor for determining level of liquid in a reservoir, a reservoir containing such sensor, and a method for determining level using such sensor. The sensor comprises a liquid-proof housing, at least one actuator operatively connected to the inner side of the housing and configured to generate vibrations, and at least one vibration sensor operatively connected town inner side of the housing and configured to measure vibrations. The actuator comprises an electromagnet directly or indirectly fixedly connected to the inner side of the housing, and a permanent magnet movably suspended in the housing, wherein the electromagnet and the permanent magnet are configured such that activation of the actuator creates an oscillating mutual displacement in parallel with a longitudinal center axis of the electromagnet.

Abstract: A mixer assembly for generating and maintaining a motion within a volume of liquid, the mixer assembly including a motor, a drive shaft and a propeller connected to the drive shaft. When the propeller is in operation, it is driven by the motor and rotates about a propeller axis. The mixer assembly's motor comprises a stator and a hybrid type rotor. The hybrid rotor includes a rotor core comprising an annular radially outer section of asynchronous type and an annular radially inner section of synchronous type arranged radially inside the annular radially outer section.

Abstract: The present invention relates to pumps comprising variable frequency drive means and methods for operating such pumps. The inventive method for operating a pump (1) comprises the steps of obtaining values of operating parameters of the pump (1) indicating pump conditions, communicating said values of operating parameters from variable frequency drive means (2) to a control device (11), determining if a predetermined condition is fulfilled, communicating instructions from the control device (11) to the variable frequency drive means (2), based on the fulfillment of said predetermined condition. Furthermore, a computer program product loadable into a memory of a digital computer device, including software code portions for performing the inventive method, a pump (1), a pump system and a control device (11) for a pump are described.