Circuit for controlling multiple rated motors

A circuit for controlling a multi-rated motor, comprising:

• a high torque contactor for connecting electrical power to the windings of a multi-rated motor such that the windings are first connected in a .DELTA.-delta configuration;
• (b) a first timer means electrically connected to the high torque contactor and a low torque contactor for de-energizing the high torque contactor and energizing the low torque contactor to change the connection of electrical power to the windings such that the windings are connected to a .gamma.-wye configuration after a predetermined time interval;
• (c) a low torque overload means connected to the low torque contactor and the .gamma.-wye connected windings for causing the low torque contactor to de-energize and energize a medium torque contactor to change the connection of electrical power to the windings such that the windings are connected in a .gamma.-.DELTA.-partial wye, partial delta configuration if the current in the windings exceed a predetermined current level;
• (d) a medium torque monitoring means for causing the windings to be switched back to a wye configuration after operating a predetermined time in the partial wye, partial delta configuration;
• (e) a medium torque overload means connected to the medium torque contactor and the .gamma.-.DELTA. partial wye, partial delta, windings for de-energizing the medium torque contactor and energizing the high torque contactor to change the connection of electrical power to the windings such that the windings are connected in a .DELTA.-delta configuration if the current in the windings exceed a predetermined current level;
• (f) a high torque monitoring means for causing the windings to be switched back to (a partial wye, partial delta) configuration after operating a predetermined time in the delta configuration;
• and
• (g) high torque overload means connected to the high torque contactor and the .DELTA.-delta connected windings for causing the disconnection of electrical power to the windings if the current in the windings exceed a predetermined current level.