Allen-bradley Company, LLC

Li Chen

Peter J Unsworth

A method and apparatus to be used with a motor controller for determining RMS line current during a start-up period or a stalled period using electrical values known to the controller. Various equations relate RMS line current to monitored thyristor and source voltages as well as the duration of non-conducting periods in line voltages to determine the RMS line current.

Method and apparatus for RMS current measurement in induction motors

A method and apparatus to be used with a motor controller for determining if phase currents in a three phase AC motor are balanced. The phase angles between current zero crossing times for consecutive phase currents are compared to determine current balance and thyristor switches are employed to adjust phase angles and rebalance unbalanced currents.

Method and apparatus for current rebalance in induction motor

A method and/or apparatus used with a motor controller for finding RMS current and RMS terminal voltage in a three phase AC induction motor using electrical values known to the controller. An equation relates average current to RMS current as a function of the duration of a known non-conducting period. Another equation relates known voltages to RMS terminal voltage as a function of a known phase angle and the known duration of the non-conducting period in a supply line.

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Milwaukee, WI, United States of America

Li Chen