Abstract: In a paper or board machine, the cross-direction profile of a flow channel defined between a first dewatering element (52, 53) situated inside a first forming wire loop (50) and a second dewatering element (64, 65) situated inside a second forming wire loop (60) is measured, and the location and/or the position of the blade element (64, 65) is adjusted based on the measurement result in order to regulate the thickness profile of a stock flow. The measurement can be by passing an alternating current of low frequency to a current rail situated in the second dewatering element (64, 65) and by measuring the strength of the magnetic field created by it by at least two measuring devices which have been placed either in the first dewatering element (53) or, when the first dewatering element is a forming roll (52), in the same dewatering element (64) as the current rail.

Abstract: In a paper or board machine, the cross-direction profile of a flow channel defined between a first dewatering element (52, 53) situated inside a first forming wire loop (50) and a second dewatering element (64, 65) situated inside a second forming wire loop (60) is measured, and the location and/or the position of the blade element (64, 65) is adjusted based on the measurement result in order to regulate the thickness profile of a stock flow. The measurement can be by passing an alternating current of low frequency to a current rail situated in the second dewatering element (64, 65) and by measuring the strength of the magnetic field created by it by at least two measuring devices which have been placed either in the first dewatering element (53) or, when the first dewatering element is a forming roll (52), in the same dewatering element (64) as the current rail.

Abstract: The invention relates to an actuator comprising a motor (4) by which the shafts (1, 5, 7) of the actuator are driven. At least one magnet (20 is arranged in conjunction with the shaft (1, 5, 7). The actuator further comprises at least one Hall sensor (3), which generates pulses as the magnet (2) on the shaft (1, 5, 7) passes the Hall sensor (3) as the shaft (1, 5, 7) rotates. The pulses are used to define the position of the actuator in the linear direction.

Abstract: The invention relates to a method and an apparatus for defining the position of an actuator. The position of the actuator (1) is measured by a measuring signal (3) proportional to the rotation of a shaft (6) of the actuator (1). The measuring signal (3) comprises successive pulses. The intervals between the pulses are divided into parts, and the position of the actuator (1) between the pulses is defined utilizing the parts of the divided pulse intervals.

Abstract: The invention relates to a method for positioning an actuator. In the method, the actuator is controlled by a continuous control pulse (2a) toward a desired value (1), and the position of the actuator is measured. Further, a pulsing range limit located before the desired value (1) is defined, and when the position of the actuator is past the pulsing range limit (3), the motion of the actuator is stopped. The pulsing range limit (3) is defined to be so far from the desired value (1) that the actuator stops before its position is substantially past the desired value (1). The position of the actuator is then measured, and if necessary, a corrective run is performed.