Electricity: motive power systems – Induction motor systems – Primary circuit control
Reexamination Certificate
2005-08-29
2008-03-18
Donovan, Lincoln (Department: 2837)
Electricity: motive power systems
Induction motor systems
Primary circuit control
C318S778000, C318S727000, C318S809000, C323S901000, C323S238000, C323S321000
Reexamination Certificate
active
07345449
ABSTRACT:
A polyphase AC induction motor is connected to a power supply through a soft starter having three sets of inverse parallel connected silicon controlled rectifiers with each set corresponding to one particular phase. Low speed starting and operation of the motor can be accomplished through triggering circuits controlling the phases of the triggering pulses in relation to the phases of the supply. The low motor speeds are developed by a gating sequence that generates a low frequency waveform that is less than the main supply frequency to the motor. This low frequency waveform is current and voltage controlled by the gating sequence to permit the AC motor to smoothly operate at speeds less than 100% of rated while developing net positive torque at the low controlled operating frequency.
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Barie Walter G.
Hagerty Harold D.
Vines Ronald E.
Benshaw, Inc.
Colon Eduardo
Donovan Lincoln
Friedman Barry I.
Metz Lewis LLC
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