Patent ID: 6782989
Filing Date: 2004-08-31
Classification: B66B,Y02B

Abstract:
Process for controlling a drive means of a conveyor system (10), specifically, in a form of an escalator or a passenger conveyor, which can be switched between a load and a no-load operation, the drive means including a drive motor (26) and a variable frequency converter (42), wherein the frequency converter is at least controllable in terms of an output frequency of an output voltage, the process comprising the steps of:supplying, the drive motor (26) with a line voltage with an essentially constant line frequency in the load operation; supplying the drive motor (26), with the output voltage of the variable frequency converter (42) in the no-load operation; wherein prior to a changeover from the no-load to the load operation or vice versa, essentially bringing the output frequency of the variable frequency converter (42) to the line frequency and determining that a phase of the line voltage is essentially in conformance with a phase of the output voltage of the variable frequency converter by means of a PLL device (30).