Abstract: A method for operating a winch system, and an arrangement including at least two electric drives each configured to operate a respective winch including a winch drum to spool a spoolable medium, and an electric motor to rotate the winch drum, each of the winches having an active state, in which the winch drum is driven according to a predetermined tension set point value, and a passive state, in which the winch drum is prevented from rotating, wherein, during a mooring of a vessel, the arrangement is configured to operate the at least two winches such that, over a period of time, each of the at least two winches is operated in its active state for a portion of the period, and each of the at least two winches is operated in its passive state for a portion of the period.

Abstract: A method for operating a towing winch and an electric drive for a towing winch, the towing winch including a rotatable winch drum for spooling a spoolable medium, and an electric motor operably coupled to the winch drum to rotate the winch drum, wherein the electric drive is configured to be operably coupled to the electric motor, and configured to control, during a towing of at least one object connected to the spoolable medium, a tension of the spoolable medium between the winch drum and the at least one object to be towed to be equal to or lower than a tension limit value; and monitor, during the towing, a roll angle of the tug, and in response to the monitored roll angle of the tug being outside of a predetermined range, lower the tension limit value providing roll compensation.

Abstract: A method for operating a towing winch and an electric drive for a towing winch, the towing winch including a rotatable winch drum for spooling a spoolable medium, and an electric motor operably coupled to the winch drum to rotate the winch drum, wherein the electric drive is configured to be operably coupled to the electric motor, and configured to control, during a towing of at least one object connected to the spoolable medium, a tension of the spoolable medium between the winch drum and the at least one object to be towed to be equal to or lower than a tension limit value; and monitor, during the towing, a roll angle of the tug, and in response to the monitored roll angle of the tug being outside of a predetermined range, lower the tension limit value providing roll compensation.

Abstract: A method for operating a winch and a winch comprising a winch drum for spooling a spoolable medium for mooring a vessel, and a winch drive configured to drive the winch drum, wherein, during the driving of the winch drum, at least when a monitored tension of the spoolable medium is between a second upper tension threshold and a second lower tension threshold, an absolute value of the driving speed of the winch drum is configured to have a value that is proportional to an absolute value of a difference between the monitored tension of the spoolable medium and a predetermined tension set point.

Abstract: A method for operating a winch and an electric drive for driving a winch including a rotatable winch drum for spooling a spoolable medium and an electric motor operably coupled to the winch drum, the electric drive being configured to drive the winch drum by driving the electric motor such that a tension of the spoolable medium reaches a predetermined tension set point value or value range, and set a driving speed of the electric motor to zero, and after the setting of the driving speed of the electric motor to zero, drive the electric motor to alternate directions of rotation at predetermined driving speeds such that the direction of rotation is changed at a predetermined frequency.

Abstract: A method for operating a winch and a winch having a winch drum for spooling a spoolable medium, wherein the winch drum is rotatable about a first axis, a guiding member for guiding the spoolable medium, wherein the guiding member is movable along a second axis between two end positions, and an electric drive having a first electric motor for driving the guiding member towards one of the two end positions during spooling in or spooling out of the spoolable medium. The electric drive is configured to change the driving direction of the guiding member when a monitored torque of the first electric motor, or a quantity indicative thereof, exceeds a predetermined threshold.

Abstract: A method for operating a winch and a winch comprising a winch drum (20) for spooling a spoolable medium (10) for mooring a vessel, and a winch drive (30, 40, 41) configured to drive the winch drum (20), wherein, during the driving of the winch drum (20), at least when a monitored tension of the spoolable medium (10) is between a second upper tension threshold and a second lower tension threshold, an absolute value of the driving speed of the winch drum is configured to have a value that is proportional to an absolute value of a difference between the monitored tension of the spoolable medium and a predetermined tension set point.

Abstract: A method for operating an anchor winch and an anchor winch for a vessel (100), comprising a winch drum (20) and an electric drive (30, 40, 41) configured to raise the anchor (11) by driving the winch drum (20) with an electric motor (30), to detect a first increase in a torque produced by the electric motor (30), which is higher than a first predetermined torque threshold, a subsequent decrease in the torque produced by the electric motor (30), which lasts for at least a predetermined time threshold and during which decrease a rate of decrease is within a predetermined range, and a subsequent second increase in the torque produced by the electric motor (30), which is higher than a second predetermined torque threshold, and, in response to detecting the second increase, determine that the anchor (30) has risen above a water surface (200) of a body of water.

Abstract: A method for operating a winch and a winch having a winch drum for spooling a spoolable medium, wherein the winch drum is rotatable about a first axis, a guiding member for guiding the spoolable medium, wherein the guiding member is movable along a second axis between two end positions, and an electric drive having a first electric motor for driving the guiding member towards one of the two end positions during spooling in or spooling out of the spoolable medium. The electric drive is configured to change the driving direction of the guiding member when a monitored torque of the first electric motor, or a quantity indicative thereof, exceeds a predetermined threshold.

Abstract: A method and arrangement for soft start up of a pump system, that includes a pump for generating a liquid flow, an electrical drive disposed to actuate the pump, and a pressure sensor disposed to measure a liquid pressure at a flow output of the pump. The rate of change of rotation speed of the pump during a start up phase is dependent on a rate of change of measured liquid pressure, wherein the rate of change of the rotation speed is a descending function of the rate of change of the measured liquid pressure.

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 electrically driven mooring winch is provided. The mooring winch includes a winding drum, an AC motor configured to drive the winding drum, a frequency conversion unit connected to the AC motor, and a control unit configured to control the frequency conversion unit on the basis of an indicator for tension of the mooring rope. The control unit is configured to set a reference value of rotational speed of the AC motor to a predetermined value, drive the AC motor in one direction for a predetermined time interval, define a first value of a torque of the AC motor, drive the AC motor in an opposite direction for the predetermined interval, define a second value of the torque of the AC motor, and compute a torque estimate using the first and second values of the torque.

Abstract: A method and arrangement are provided for operating a ship ramp driven by an electric motor between an upper end position and a lower end position. The arrangement includes means for reducing the maximum torque of the at least one electric motor when the ramp is in proximity to an end position of the ramp, and means for determining the position of the ramp on the basis of at least one of the number of rotations performed by the at least one electric motor, a quantity indicative of the number of rotations, and an elapsed time in accordance with the velocity of the ramp. The arrangement also includes means for allowing the reduction of the maximum torque of the at least one electric motor only when the determined position of the ramp is within a zone defined by predetermined limits.

Abstract: A method and arrangement for limiting an electric power required by at least two electric loads, each of which has a predetermined priority level, the arrangement comprising means (31, 32, 33) for monitoring a total electric power required by the at least two electric loads (21, 22, 23), and means (31, 32, 33) for reducing, in a priority-level-wise manner, individual electric powers required by the electric loads (21, 22, 23) having the predetermined priority levels by starting from electric load or loads having the lowest priority level and proceeding, one priority level at a time, towards the highest priority level until the monitored total electric power does not exceed a predetermined threshold value.

Abstract: An electrically driven mooring includes a winding drum (101), an alternating current motor (103) arranged to drive the winding drum, a frequency conversion unit (104) connected to the alternating current motor, and a control unit (105) arranged to control the frequency conversion unit on the basis of an indicator for tension of the mooring rope. The control unit is arranged to compute a flux space vector for modelling a stator flux of the alternating current motor, to compute a torque estimate on the basis of the flux space vector and a space vector of stator currents, and to use the torque estimate as the indicator for the tension of the mooring rope. Hence, a need for a force sensor on the mooring rope and a need for a speed/position sensor on the motor shaft can be avoided.

Abstract: An electrically driven mooring winch is provided. The mooring winch includes a winding drum, an AC motor configured to drive the winding drum, a frequency conversion unit connected to the AC motor, and a control unit configured to control the frequency conversion unit on the basis of an indicator for tension of the mooring rope. The control unit is configured to set a reference value of rotational speed of the AC motor to a predetermined value, drive the AC motor in one direction for a predetermined time interval, define a first value of a torque of the AC motor, drive the AC motor in an opposite direction for the predetermined interval, define a second value of the torque of the AC motor, and compute a torque estimate using the first and second values of the torque.

Abstract: A method and arrangement are provided for operating a ship ramp driven by an electric motor between an upper end position and a lower end position. The arrangement includes means for reducing the maximum torque of the at least one electric motor when the ramp is in proximity to an end position of the ramp, and means for determining the position of the ramp on the basis of at least one of the number of rotations performed by the at least one electric motor, a quantity indicative of the number of rotations, and an elapsed time in accordance with the velocity of the ramp. The arrangement also includes means for allowing the reduction of the maximum torque of the at least one electric motor only when the determined position of the ramp is within a zone defined by predetermined limits.

Abstract: A method and arrangement for limiting an electric power required by at least two electric loads, each of which has a predetermined priority level, the arrangement comprising means (31, 32, 33) for monitoring a total electric power required by the at least two electric loads (21, 22, 23), and means (31, 32, 33) for reducing, in a priority-level-wise manner, individual electric powers required by the electric loads (21, 22, 23) having the predetermined priority levels by starting from electric load or loads having the lowest priority level and proceeding, one priority level at a time, towards the highest priority level until the monitored total electric power does not exceed a predetermined threshold value.

Abstract: An electrically driven mooring includes a winding drum (101), an alternating current motor (103) arranged to drive the winding drum, a frequency conversion unit (104) connected to the alternating current motor, and a control unit (105) arranged to control the frequency conversion unit on the basis of an indicator for tension of the mooring rope. The control unit is arranged to compute a flux space vector for modelling a stator flux of the alternating current motor, to compute a torque estimate on the basis of the flux space vector and a space vector of stator currents, and to use the torque estimate as the indicator for the tension of the mooring rope. Hence, a need for a force sensor on the mooring rope and a need for a speed/position sensor on the motor shaft can be avoided.

Abstract: The invention relates to a method and an arrangement for measuring a liquid flow in connection with a pump system. The invention is preferably implemented in a pump system where the pump (240) is driven by an alternating-current motor (230), whose rotating speed is controlled by a control unit (220), such as a frequency converter, for instance. In accordance with the invention, 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 comprise 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 i.a. at the frequency converter (220). In addition, the static liquid pressure can be measured by means of a straightforward and reliable pressure sensor (244, 245), which can be integrated in the pump system.