Abb Automation Gmbh

Charles J Dubats

Donald J Truettner

Kari A Tikkanen

A man machine interface for an A-C motor bypass has a membrane keypad with a multiplicity of pushbuttons connected to a micro-controller. The micro-controller controls the flow of current to the coil of each of the drive and bypass contactors to thereby open or close those contactors depending on if the motor is to be driven and how it is to be driven. The micro-controller includes code that simulates a first state machine that determines the operating condition of the drive and bypass contactors and if it is desired to open that one of the two contactors which is presently open and close that one of the two contactors when is presently open. The micro-controller includes code which simulates a second state machine which is active only when the inverter contactor is open. This state machine determines if the motor is to run or stop and closes or opens the bypass contactor accordingly. The micro-controller includes a non-volatile memory that is used to store the last operating mode of the bypass operating condition if that mode was either automatic operation of the motor, that is, the motor is connected to an A-C source through the inverter in the bypass, or off.

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New Berlin, WI, United States of America

Charles J Dubats