Bidirectional zero speed switch

Claim 2

In a control circuit for a reversible polyphase a.c. induction motor having supply lines for providing polyphase voltage to the motor, the combination comprising a plurality of sensing means for sensing the voltage on the motor supply lines resulting from the applied voltage and the generator action of the motor and in response thereto emitting a plurality of output signals, logic means for comparing the relative phase of the plurality of output signals thereby to determine the presence and direction of motor rotation, and interlocking means responsive to the logic circuitry for selectively interrupting the motor control circuit thereby to allow voltage to cause either direction of rotation to be applied to the motor while at rest, but to allow voltage to be applied to the motor while coasting only if that voltage will cause the motor to continue in its direction of coast.

Claim 3

In a control circuit for a reversible three phase a.c. induction motor having supply lines for providing three phase voltage to the motor, the combination comprising first and second amplifier means for sensing the voltage on the motor supply lines resulting from the applied voltage and the generator action of the motor and in response thereto emitting respectively first and second output signals, logic circuitry means for comparing the relative phase of the first and second output signals and in response thereto assuming one of three distinct states corresponding to (a) clockwise motor rotation (b) counterclockwise motor rotation or (c) no motor rotation, and interlocking means responsive to the logic circuitry for selectively interrupting the control circuit so that voltage may be applied to the motor to cause rotation in either clockwise or counterclockwise direction when the logic circuitry is in the ''''no motor rotation'''' condition, while voltage may be applied to the motor when the logic circuitry is in either of its other two conditions only if that voltage will cause the motor to continue in its direction of rotation.

Claim 4

In a control circuit for a reversible three phase a.c. induction motor having supply lines for providing three phase voltage to the motor, the combination comprising first and second amplifier means for sensing the voltage on the motor supply lines resulting from the applied voltage and the generator action of the motor and in response thereto emitting respectively first and second output signals, logic circuitry means for comparing the relative phase of the first and second output signals and in response thereto assuming one of three distinct states corresponding to (a) clockwise motor rotation (b) counterclockwise motor rotation or (c) no motor rotation, and interlocking means responsive to the logic circuitry for selectively interrupting the control circuit so that voltage may be applied to the motor to cause rotation in either clockwise or counterclockwise direction when the logic circuitry is in the ''''no motor rotation'''' condition, while voltage may be applied to the motor when the logic circuitry is in either of its other two conditions only if that voltage will cause the motor to continue in its direction of rotation.

Claim 5

In a control circuit for a reversible three phase a.c. induction motor having supply lines for providing three phase voltage to the motor, the combination comprising first and second amplifier means for sensing the voltage on the motor supply lines resulting from the applied voltage and the generator action of the motor and in response to the presence of a voltage emitting respectively first and second output signals, logic circuitry including first and second bi-stable elements responsive respectively to the first and second output signals, each of the bi-stable elements driven into its first stable state in response to the simultaneous absence of the first and second output signals, and driven into its second stable state in response To the presence of its associated output signal, the bi-stable elements cross-associated so that when one of the bi-stable elements is in its second stable state the other bi-stable element is prevented from responding to its associated output signal, and interlocking means responsive to the logic circuitry for selectively interrupting the control circuit thereby to allow voltage to cause either direction of motor rotor to be applied to the motor while at rest, but to allow voltage to be applied to the motor while coasting only if that voltage will cause the motor to continue in its direction of coast.

Claim 6

In a control circuit for a reversible three phase a.c. induction motor having supply lines for providing three phase voltage to the motor, the combination comprising first and second amplifier means for sensing the voltage on the motor supply lines resulting from the applied voltage and the generator action of the motor and in response to the presence of a voltage emitting respectively first and second output signals, logic circuitry including first and second bi-stable elements responsive respectively to the first and second output signals, each of the bi-stable elements driven into its first stable state in response to the simultaneous absence of the first and second output signals, and driven into its second stable state in response To the presence of its associated output signal, the bi-stable elements cross-associated so that when one of the bi-stable elements is in its second stable state the other bi-stable element is prevented from responding to its associated output signal, and interlocking means responsive to the logic circuitry for selectively interrupting the control circuit thereby to allow voltage to cause either direction of motor rotor to be applied to the motor while at rest, but to allow voltage to be applied to the motor while coasting only if that voltage will cause the motor to continue in its direction of coast.

Claim 7

In a control circuit for a reversible three phase a.c. induction motor having supply lines for providing three phase voltage to the motor, the combination comprising first and second means for sensing the voltage on the motor supply lines resulting from the applied voltage and the generator action of the motor and in response to the presence of a voltage emitting respectively first and second output signals, logic circuitry including first and second bi-stable elements responsive respectively to the first and second output signals, each of the bi-stable elements driven into its first stable state in response to the simultaneous absence of the first and second output signals and driven into its second stable state in response to the presence of its associated output signal, the bi-stable elements cross-associated so that when one of the bi-stable elements is in its first state the other bi-stable element is prevented from responding to its associated output signal, the logic circuitry also including first gating circuit responsive to the first bi-stable element and the second output signal and second gating circuit responsive to the second bi-stable element and the first output signal, and first and second interlocking means responsive respectively to first and second gating circuits for selectively interrupting the control circuit thereby to allow voltage to cause either direction of motor rotor to be applied to the motor while at rest, but to allow voltage to be applied to the motor while coasting only if that voltage will cause the motor to continue in its direction of coast.

Claim 8

In a control circuit for a reversible three phase a.c. induction motor having supply lines for providing three phase voltage to the motor, the combination comprising first and second means for sensing the voltage on the motor supply lines resulting from the applied voltage and the generator action of the motor and in response to the presence of a voltage emitting respectively first and second output signals, logic circuitry including first and second bi-stable elements responsive respectively to the first and second output signals, each of the bi-stable elements driven into its first stable state in response to the simultaneous absence of the first and second output signals and driven into its second stable state in response to the presence of its associated output signal, the bi-stable elements cross-associated so that when one of the bi-stable elements is in its first state the other bi-stable element is prevented from responding to its associated output signal, the logic circuitry also including first gating circuit responsive to the first bi-stable element and the second output signal and second gating circuit responsive to the second bi-stable element and the first output signal, and first and second interlocking means responsive respectively to first and second gating circuits for selectively interrupting the control circuit thereby to allow voltage to cause either direction of motor rotor to be applied to the motor while at rest, but to allow voltage to be applied to the motor while coasting only if that voltage will cause the motor to continue in its direction of coast.

Claim 9

In a control circuit for a reversible three phase a.c. induction motor having supply lines for providing three phase voltage to the motor, the combination comprising first and second amplifier means for sensing the voltage on the motor supply lines resulting from the applied voltage and the generator action of the motor and in response to the presence of a voltage emitting respectively first and second output signals, logic circuitry including first and second bistable elements responsive respectively to the first and second output signals, each of the bi-stable elements driven into its first stable state in response to the simultaneous absence of the first and second output signals and driven into its second stable state in response to the presence of its associated output signal, the bi-stable elements cross-associated so that when one of the bi-stable elements is in its first stable state the other bi-stable element is prevented from responding to its associated output signal, and interlocking circuitry responsive to the logic circuitry the interlocking circuitry including interlocking relays whose contacts are so disposed in the motor control circuit as to allow voltage to cause either direction of motor rotation to be applied to the motor while at rest, but to allow voltage to be applied to the motor while coasting only if that voltage will cause the motor to continue in its direction of coast.

Claim 10

In a control circuit for a reversible three phase a.c. induction motor having supply lines for providing three phase voltage to the motor, the combination comprising first and second amplifier means for sensing the voltage on the motor supply lines resulting from the applied voltage and the generator action of the motor and in response to the presence of a voltage emitting respectively first and second output signals, logic circuitry including first and second bistable elements responsive respectively to the first and second output signals, each of the bi-stable elements driven into its first stable state in response to the simultaneous absence of the first and second output signals and driven into its second stable state in response to the presence of its associated output signal, the bi-stable elements cross-associated so that when one of the bi-stable elements is in its first stable state the other bi-stable element is prevented from responding to its associated output signal, and interlocking circuitry responsive to the logic circuitry the interlocking circuitry including interlocking relays whose contacts are so disposed in the motor control circuit as to allow voltage to cause either direction of motor rotation to be applied to the motor while at rest, but to allow voltage to be applied to the motor while coasting only if that voltage will cause the motor to continue in its direction of coast.

Claim 11

In a control circuit for a reversible three phase a.c. induction motor having supply lines for providing three phase voltage to the motor, the combination comprising first and second amplifier means for sensing the voltages on the motor supply lines resulting from the applied voltage and the generator action of the motor and in response thereto emitting first and second output signals said Output signals being out of phase in response to the phase relationship of the voltages on the motor supply lines the phase relationship being indicative of the direction of motor rotation, logic circuitry including first and second bi-stable elements responsive to the phase relationships of the output signals both of said bi-stable elements normally maintained in their first stable state, the first bi-stable element driven into its second stable state in response to one direction of motor rotation, the second bi-stable element driven into its second stable state in response to the opposite direction of motor rotation, and interlocking means responsive to the logic circuitry for selectively interrupting the control circuit thereby to allow voltage to cause either direction of motor rotor to be applied to the motor while at rest, but to allow voltage to be applied to the motor while coasting only if that voltage will cause the motor to continue in its direction of coast.

Claim 12

In a control circuit for a reversible three phase a.c. induction motor having supply lines for providing three phase voltage to the motor, the combination comprising first and second amplifier means for sensing the voltages on the motor supply lines resulting from the applied voltage and the generator action of the motor and in response thereto emitting first and second output signals said Output signals being out of phase in response to the phase relationship of the voltages on the motor supply lines the phase relationship being indicative of the direction of motor rotation, logic circuitry including first and second bi-stable elements responsive to the phase relationships of the output signals both of said bi-stable elements normally maintained in their first stable state, the first bi-stable element driven into its second stable state in response to one direction of motor rotation, the second bi-stable element driven into its second stable state in response to the opposite direction of motor rotation, and interlocking means responsive to the logic circuitry for selectively interrupting the control circuit thereby to allow voltage to cause either direction of motor rotor to be applied to the motor while at rest, but to allow voltage to be applied to the motor while coasting only if that voltage will cause the motor to continue in its direction of coast.