Abstract: A method and arrangement for soft start up of a pump system, that includes a pump (401) for generating a liquid flow, an electrical drive (402, 403, 404) disposed to actuate the pump, and a pressure sensor (408) disposed to measure a liquid pressure at a flow output of the pump. The objectives of the invention are achieved with a solution in which a rate of change of rotation speed of the pump during a start up phase is made to be dependent on a rate of change of measured liquid pressure speed is a descending function of the rate of change of the measured liquid pressure.

Abstract: Method and arrangement for measuring a liquid flow in connection with a pump system, where the pump is driven by an alternating-current motor, whose rotating speed is controlled by a control unit. The flow is determined without any direct flow measurement by utilizing characteristic data of the pump and parameters that can be easily and reliably measured. Such parameters include the rotation speed of the pump, the liquid pressure and/or the motor power. Both the motor power and the rotation speed can be measured at the frequency converter. The static liquid pressure can be measured by a straightforward and reliable pressure sensor, which can be integrated in the pump system. In implementing the invention, two characteristic curves of the pump can be advantageously used; flow as a function of power and flow as a function of pressure. This achieves high accuracy of measurement both with low and high flow values.

Abstract: A method and an arrangement for controlling a pump station includes measurement of the surface level of a liquid (465) by means of a sensor (452) and controlling the electric drive (401, 420, 430) of the pump (440) to a predetermined speed of rotation when a specific surface level value has been reached. This predetermined rotation speed value is preferably the rotation speed at which the ratio of the flow rate to the consumed power, i.e. the efficiency, is optimal. The measurement of the surface level and the related data processing for control of the pump are performed in a frequency converter (420) in conjunction with the control.

Abstract: An industrial robot having a first part and a second part that are arranged to be movable with respect to each other where at least one cable extends from the first part to the second part via an internal cavity. An excess of cable extends freely through the internal cavity from the first part to the second part. At least one cable is connected to at least one of the parts via a releasable contact point that is located inside the internal cavity.