Importance

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Abstract

There is provided an electrical inching control for inching a drive system comprising a grinding mill driven by one or more three phase synchronous motors. The electric inching control includes an inching power bus and contactors or the solid state equivalent thereof. The inching bus supplies energy for the stator windings of the synchronous motors. The contactors or switches connect the positive and negative sides of a direct current power supply to the different phases of the stator windings in a sequence which provides a stepped rotating magnetic field, and the rotor field windings are excited with direct current. The interacting stator and rotor fields causes a rotation of the rotor a predetermined amount with each step causing the mill also to rotate a respective predetermined amount. The electric inching control of the present invention further includes a vibration sensor which detects vibration in the gearing driving the mill and the signal from the vibration sensor is applied to a feedback voltage magnitude control which adjusts the magnitude of voltage applied to the stator windings of the synchronous motors reducing the voltage as the signal representing vibration increases to reduce the adverse mechanical forces incurred by the mill.

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First Claim