Detection of electric motor short circuits
AssigneeRockwell Automation Technologies, Inc.
InventorsChristopher H. Bock, Christopher J. Wieloch, James J. Kinsella, Stefan T. Dziekonski
Life of this patent
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Abstract
One embodiment describes a method that includes determining a desired torque level of a motor actuated by a motor starter; determining, using a control system, a configuration of the motor starter to achieve the desired torque level, in which determining the configuration includes determining which of a plurality of switching devices in the motor starter should be opened and which should be closed; and instructing, using the control system, the motor starter to implement the determined configuration by opening or closing one or more of the plurality of switching devices.
Claims19
A method comprising:
- detecting whether a phase-to-ground short is present in a first winding of a motor by briefly connecting a first phase of electric power to the motor slightly before a voltage zero-crossing by the first phase of electric power;
- detecting whether a phase-to-ground short is present in a second winding of a motor by briefly connecting a second phase of electric power to the motor slightly before a voltage zero-crossing by the second phase of electric power;
- and
- detecting whether a phase-to-ground short is present in a third winding of a motor drive by briefly connecting a third phase of electric power to the motor slightly before a voltage zero-crossing by the third phase of electric power.
A switchgear system, comprising:
- a first switching device configured to selectively connect and disconnect a first phase of electric power to a first winding of a motor;
- a second switching device configured to selectively connect and disconnect a second phase of electric power to a second winding of the motor;
- a third switching device configured to selectively connect and disconnect a third phase of electric power to a third winding of the motor;
- and
- a control circuitry configured to:
- instruct the first switching device to briefly connect the first phase of electric power to the motor slightly before a voltage zero-crossing by the first phase to detect whether a phase-to-ground short is present in the first winding;
- instruct the second switching device to briefly connect the second phase of electric power to the motor slightly before a voltage zero-crossing by the second phase to detect whether a phase-to-ground short is present in the second winding;
- and
- instruct the third switching device to briefly connect the third phase of electric power to the motor slightly before a voltage zero-crossing by the third phase to detect whether a phase-to-ground short is present in the third winding.
A switchgear system, comprising:
- a first switching device;
- and
- a second switching device coupled in series with the first switching device, wherein the first switching device and the second switching device are configured to briefly supply a first phase of electric power to a first winding of a motor by:
- closing the first switching device at a first time;
- closing the second switching device at a second time;
- opening the first switching device at a third time;
- and
- opening the second switching device at a fourth time such that the first phase of electric power is supplied to the first winding between the second time and the third time to determine whether fault is present in the motor;
- the second time and the third time are slightly before a voltage zero-crossing by the first phase.
Dependencies are inferred from the claim text.