Phase correction method and apparatus
First Claim
1. A method of determining whether a 3 phase motor is rotating in the proper direction, comprising the steps of:
- energizing the motor to operate in one direction for a first preselected period of time;
measuring the current flow to the motor during said first period of time and recording the first measurement;
energizing the motor to run in the other direction for a second preselected period of time;
measuring the current flow to the motor during said second period of time and recording the second measurement;
comparing said first and second measurements to determine which is greater and therefore in proper phase relationship.
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Accused Products
Abstract
In a transport refrigeration system which is susceptible to having its drive motors connected to a power source in reverse phase relationship to thereby operate the drive motors in reverse, provision is made to measure the current flow to the motors during operation in each direction and for comparing those current flows to determine which is greater and therefore representative of operation in the proper direction. A backup method is also provided for sensing the ambient temperature of the air downstream of the condenser coil, both before and during motor operation to determine whether the temperature during motor operation is greater than that prior to operation to thereby indicate a proper connection.
7 Citations
14 Claims
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1. A method of determining whether a 3 phase motor is rotating in the proper direction, comprising the steps of:
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energizing the motor to operate in one direction for a first preselected period of time;
measuring the current flow to the motor during said first period of time and recording the first measurement;
energizing the motor to run in the other direction for a second preselected period of time;
measuring the current flow to the motor during said second period of time and recording the second measurement;
comparing said first and second measurements to determine which is greater and therefore in proper phase relationship. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An improved transport refrigeration system of the type having a plurality of three-phase motors which are periodically connected to different power sources so as to be susceptible to being connected in a phase relationship such that the motors are caused to operate in reverse comprising:
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at least one current measuring device for measuring the current flow to at least one of said motors when operating in one direction and for subsequently measuring the current flow to said at least one motor when operating in the other direction; and
a comparator for comparing the two measured current flows to determine which is greater and therefore in proper phase relationship. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification