Systems and methods for protecting three-phase motors
First Claim
1. A system for protecting a three-phase electric motor of a compressor, the motor receiving first, second, and third phases from a three-phase power supply, the system comprising:
- a single-phase line break protector that disconnects the motor from the first phase in response to a temperature being greater than a predetermined temperature threshold;
a first current sensor that measures a current through the single-phase line break protector; and
a control module that (i) determines a current value based on the measured current, and (ii) disconnects the motor from the second and third phases in response to the current value being less than or equal to a predetermined threshold,wherein the control module disconnects the motor from the first, second, and third phases when the current value is less than or equal to the predetermined threshold, andwherein the current value includes one of a peak of the measured current during a predetermined period and a root mean squared (RMS) of the measured current during the predetermined period.
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Accused Products
Abstract
A system for protecting a three-phase electric motor of a compressor, the motor receiving first, second, and third phases from a three-phase power supply, the system including a single-phase line break protector, a first current sensor, and a control module. The single-phase line break protector disconnects the motor from the first phase in response to a temperature being greater than a predetermined temperature threshold. The first current sensor measures a current through the single-phase line break protector. The control module determines a current value based on the measured current, and disconnects the motor from the second and third phases in response to the current value being less than or equal to a predetermined threshold.
20 Citations
16 Claims
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1. A system for protecting a three-phase electric motor of a compressor, the motor receiving first, second, and third phases from a three-phase power supply, the system comprising:
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a single-phase line break protector that disconnects the motor from the first phase in response to a temperature being greater than a predetermined temperature threshold; a first current sensor that measures a current through the single-phase line break protector; and a control module that (i) determines a current value based on the measured current, and (ii) disconnects the motor from the second and third phases in response to the current value being less than or equal to a predetermined threshold, wherein the control module disconnects the motor from the first, second, and third phases when the current value is less than or equal to the predetermined threshold, and wherein the current value includes one of a peak of the measured current during a predetermined period and a root mean squared (RMS) of the measured current during the predetermined period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for protecting a three-phase electric motor of a compressor, the motor receiving first, second, and third phases from a three-phase power supply, the system comprising:
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a single-phase line break protector that disconnects the motor from the first phase in response to a temperature being greater than a predetermined temperature threshold; a first current sensor that measures a current through the single-phase line break protector; a control module that determines a current value based on the measured current, and (ii) disconnects the motor from the second and third phases in response to the current value being less than or equal to a predetermined threshold, wherein the control module disconnects the motor from the first, second, and third phases when the current value is less than or equal to the predetermined threshold; and a second current sensor that measures a current corresponding to one of the second and third phases, wherein the control module selectively detects at least one of a phase loss and reversed phase sequence based on the measured currents, and wherein the control module disconnects the motor from the second and third phases in response to one or more of the phase loss and the reversed phase sequence being detected.
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10. A method for protecting a three-phase electric motor of a compressor, the motor receiving first, second, and third phases from a three-phase power supply, the method comprising:
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disconnecting the motor from the first phase using a single-phase line break protector in response to a temperature being greater than a predetermined temperature threshold; measuring a current through the single-phase line break protector; determining a current value based on the measured current; disconnecting the motor from the second and third phases in response to the current value being less than or equal to a predetermined threshold; and disconnecting the motor from the first, second, and third phases in response to the current value being less than or equal to the predetermined threshold, wherein the current value includes one of a peak of the measured current during a predetermined period and a root mean squared (RMS) of the measured current during the predetermined period. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method for protecting a three-phase electric motor of a compressor, the motor receiving first, second, and third phases from a three-phase power supply, the method comprising:
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disconnecting the motor from the first phase using a single-phase line break protector in response to a temperature being greater than a predetermined temperature threshold; measuring a current through the single-phase line break protector; determining a current value based on the measured current; disconnecting the motor from the second and third phases in response to the current value being less than or equal to a predetermined threshold; disconnecting the motor from the first, second, and third phases in response to the current value being less than or equal to the predetermined threshold; measuring a current corresponding to one of the second and third phases; selectively detecting at least one of a phase loss and reversed phase sequence based on the measured currents; and disconnecting the motor from the second and third phases in response to one or more of the phase loss and the reversed phase sequence being detected.
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Specification