Microprocessor detection of transient voltage and abnormal line voltage
First Claim
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1. Method of protecting a metal oxide varistor (MOV) from damage comprising the steps of:
- a) placing said MOV in series with a solenoid operated switch having a first position to conduct current through said MOV to an electrical load and a second position to prevent the conducting of current through said MOV to said electrical load;
b) providing a source of voltage connected to said solenoid operated switch;
c) comparing a waveform of said source of voltage to a stored value of a perfect voltage waveform; and
d) operating said solenoid operated switch to said second position if the waveform of said source of voltage exceeds a predetermined limit.
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Abstract
A method for determining the extent of a transient'"'"'s ability to cause MOV over heating and subsequent explosion by microprocessor analysis of an AC voltage input waveform with respect to a stored perfect sine wave. The microprocessor also calculates the RMS value of the applied voltage waveform and compares it to stored limits to determine if it could cause over heating of the MOV. In either case, the microprocessor will generate an out-of-range signal to a disconnect device to take the MOV, and also the load, if desired, off line until normal line voltage is restored.
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Citations
31 Claims
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1. Method of protecting a metal oxide varistor (MOV) from damage comprising the steps of:
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a) placing said MOV in series with a solenoid operated switch having a first position to conduct current through said MOV to an electrical load and a second position to prevent the conducting of current through said MOV to said electrical load; b) providing a source of voltage connected to said solenoid operated switch; c) comparing a waveform of said source of voltage to a stored value of a perfect voltage waveform; and d) operating said solenoid operated switch to said second position if the waveform of said source of voltage exceeds a predetermined limit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An apparatus for opening a circuit between a source of AC power and an electrical load to protect an MOV in parallel with said electrical load comprising:
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a) a source of AC power; b) an analog to digital converter coupled to said source of AC power to sample an input line voltage of said source of AC power; c) a first storage device for storing a perfect sine wave; and d) a first comparing device coupled to said first storage device and said analog to digital converter for comparing the waveform of the sampled input line voltage with said perfect sine wave and providing a first signal indicative of any differences between said input line voltage waveform and said perfect sine wave. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. Method of protecting a MOV from damage comprising the steps of:
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a) placing said MOV in series with a solenoid operated switch having a first position to conduct current through said MOV and a second position to prevent the conducting of current through said MOV; b) providing a source of voltage connected by a first path to said solenoid operated switch; c) coupling an electrical load to said source of voltage by a second path in parallel with said MOV; d) comparing a waveform of said source of voltage to a stored value of a perfect waveform; and e) operating said solenoid operated switch to said second position if the waveform of said source of voltage exceeds a predetermined limit to open said first path to said MOV while leaving said second path to said load complete. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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Specification