Circuit breaker static trip unit having automatic circuit trimming
First Claim
1. A static trip circuit interrupter comprising:
- separable contacts within a protected power distribution circuit;
sensing means within said system for determining magnitudes of current through said contacts;
interrupter means within said system for opening said contacts upon predetermined conditions of said current magnitudes and of time;
trip unit means, including electrically active and passive circuit components, for determining the occurrence of said predetermined conditions of current and time and for actuating said interruption means to open said contacts, said trip unit means further including electrically alterable memory means and a digital processor for providing calibration and correction facility to selected ones of said active and passive components.
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Accused Products
Abstract
An analog signal processor used within a static trip unit is provided with an A/D converter, a digital processor and an electrically alterable non-volatile memory (EAROM) for providing trimming and calibration facility to the trip unit. The EAROM provides the ability to store parameters calculated by the user during the manufacturing process of the trip unit. Key measured or environmental variables are created and a correction algorithm is generated and stored along with data. The trip unit is then capable of self-calibration by applying the correction factor to compensate for variations in the component sensitivity. In one application, the current sensing transformer is precalibrated and provided with a correction factor and a correction algorithm. In another application, the thick film resistors within the long term trip mode network, the short term trip mode network and the power supply voltage regulator are "trimmed" by means of stored correction values.
143 Citations
21 Claims
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1. A static trip circuit interrupter comprising:
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separable contacts within a protected power distribution circuit; sensing means within said system for determining magnitudes of current through said contacts; interrupter means within said system for opening said contacts upon predetermined conditions of said current magnitudes and of time; trip unit means, including electrically active and passive circuit components, for determining the occurrence of said predetermined conditions of current and time and for actuating said interruption means to open said contacts, said trip unit means further including electrically alterable memory means and a digital processor for providing calibration and correction facility to selected ones of said active and passive components. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for providing calibration and automatic correction facility to static trip circuit interrupters comprising the steps of:
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storing a correction program within memory means associated with a digital processor within a static trip unit; providing a constant current to a current transformer connected with said trip unit for generating a voltage value across a burden resistor in circuit with said static trip unit; and storing a correction factor obtained from said voltage value within said memory means.
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20. A method for providing calibration and automatic correction facility to a static trip circuit interrupter comprising the steps of:
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storing a correction program within electrically alterable memory means associated with a digital processor within a static trip unit; providing a predetermined current to electrically active circuit components contained within said static trip unit; translating said predetermined current to corresponding digital data through an A/D converter to said digital processor; translating feedback data from said digital processor through a D/A converter to an amplifier in circuit with said electrically active components; and adjusting said electrically alterable memory means in correspondence with said feedback data to provide a correction factor within said electrically alterable memory means for said electrically active circuit components. - View Dependent Claims (21)
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Specification