Patent ID: 8126583

Claim:
A method for supplying a chemical or chemical compound in a fibrous web machine during the fiber web machine operation, comprising the steps of: supplying to a common supply line the chemical or chemical compound via at least a first displacement pump having a first electric actuator and a first control drive, and a second displacement pump having a second electric actuator, and a second control drive; further supplying the chemical or chemical compound from the common supply line to an operating device of the fibrous web machine; wherein the first control drive is in controlling relation to the first electric actuator so as to control angular speed and phase angle of the first electric actuator; wherein the second control drive is in controlling relation to the second electric actuator so as to control angular speed and phase angle of the second electric actuator; measuring during the fiber web machine operation, a phase angle of the first electric actuator and a phase angle of the second electric actuator; forming a control signal based on the measured phase angle of the first electric actuator and the phase angle of the second electric actuator and transmitting the control signal to the first control drive; using the control signal during the fiber web machine operation, to control angular speed and phase angle of the first electric actuator to adjust a difference defined between the phase angles of the first electric actuator and the second electric actuator to a first selected value; and forming and transmitting an electric synchronization signal between the first control drive and the second control drive such that the first control drive and the second control drive can act on said synchronization signal to maintain the difference between the phase angles of the first electric actuator and the second electric actuator at the first selected value.