Reserve power source with power failure detection apparatus
First Claim
1. An apparatus for detecting a power failure in an alternating current power signal, said apparatus comprising:
- clock means for providing a clock signal in correspondence with a zero-crossing of said power signal, said clock signal having cycles including a first state, existing for a first time, and a second state, existing for a second time, wherein said first and second times define the period of a cycle of said clock signal and wherein at least a portion of said second time defines a trip window portion of each cycle of said clock signal;
pulse generating means for generating a single control pulse commencing in response to a voltage level of said power signal detected prior to the zero-crossing of said power signal and terminating if a voltage level of said power signal is detected after the zero-crossing of said power signal; and
means, responsive to said clock signal and said control pulse, for detecting any part of said control pulse existing at the same time as any part of said trip window portion of said clock signal, which defines the existence of a power outage condition, and for generating a signal indicating a power outage in response to a detected power outage condition.
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Accused Products
Abstract
A reserve power source, switchably connected to a network between a primary power supply and a load, provides an auxiliary power signal to the load when a power failure condition is detected in the signal from the primary power supply. The reserve power source includes a circuit for instantaneously detecting and switching upon the occurrence of a power outage. An overvoltage/noise detector circuit is included to detect when either a sustained overvoltage condition or a high, short duration overvoltage condition occurs. A low voltage detector circuit is included for detecting a low voltage, or brown-out, condition. When an overvoltage or low voltage condition is detected, a preferred embodiment of the invention switches the load to the auxiliary power signal within one-half cycle of, but in zero-crossing synchronization with, the primary power signal.
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Citations
18 Claims
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1. An apparatus for detecting a power failure in an alternating current power signal, said apparatus comprising:
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clock means for providing a clock signal in correspondence with a zero-crossing of said power signal, said clock signal having cycles including a first state, existing for a first time, and a second state, existing for a second time, wherein said first and second times define the period of a cycle of said clock signal and wherein at least a portion of said second time defines a trip window portion of each cycle of said clock signal; pulse generating means for generating a single control pulse commencing in response to a voltage level of said power signal detected prior to the zero-crossing of said power signal and terminating if a voltage level of said power signal is detected after the zero-crossing of said power signal; and means, responsive to said clock signal and said control pulse, for detecting any part of said control pulse existing at the same time as any part of said trip window portion of said clock signal, which defines the existence of a power outage condition, and for generating a signal indicating a power outage in response to a detected power outage condition. - View Dependent Claims (2, 4, 5)
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3. An apparatus for instantaneously detecting a power failure in an alternating current power signal, said apparatus comprising:
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clock means for providing a clock signal in correspondence with a zero-crossing of said power signal, said clock signal having cycles including a first state, existing for a first predetermined time, and a second state, existing for a second predetermined time, wherein said first and second predetermined times define the period of a cycle of said clock signal; pulse generating means for generating a control pulse commencing when a predetermined voltage level of said power signal is detected, said pulse generating means including a zero-crossing detector integrated circuit means, having input means for receiving said power signal, for providing said control pulse; and power outage determining means, responsive to at least a portion of said control pulse existing during at least part of the second state of at least one of the cycles of said clock signal, for instantaneously providing a power failure indicating signal when said control pulse and said second state first coincide, said power failure determining means including; light-emitting means for providing an actuation signal in response to said control pulse, said light-emitting means including a diode; and photo-responsive means, having said clock signal and said actuation signal provided thereto, for generating said power failure indicating signal when at least a portion of said actuation signal exists simultaneously with at least a portion of said second state of said clock signal, said photo-responsive means including; a first transistor optically coupled to said diode; a second transistor having a first terminal connected to said first transistor and a second terminal connected to said clock means; and a third transistor having a first terminal connected to said first terminal of said second transistor and having a second terminal through which said power failure indicating signal is provided.
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6. An apparatus for instantaneously detecting a power failure in an alternating current power signal, said apparatus comprising:
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clock means for providing a clock signal in correspondence with a zero-crossing of said power signal, said clock signal having cycles including a first state, existing for a first predetermined time, and a second state, existing for a second predetermined time, wherein said first and second predetermined times define the period of a cycle of said clock signal, said clock means including; timer means for generating said clock signal so that each cycle thereof has said first and second states; and synchronizing means, responsive to a full-wave rectification of said power signal, for synchronizing the commencement of each first state of said clock signal with a respective zero-crossing of said power signal; pulse generating means for generating a control pulse commencing when a predetermined voltage level of said power signal is detected, said pulse generating means including zero-crossing detector means, responsive to said full-wave rectification of said power signal, for providing said control pulse in correspondence with the zero-crossings of said power signal; and power failure determining means, responsive to at least a portion of said control pulse existing during at least part of the second state of at least one of the cycles of said clock signal, for instantaneously providing a power failure indicating signal when said control pulse and said second state first coincide, said power failure determining means including; a light-emitting diode connected to said zero-crossing detector means; a first transistor optically responsive to said light-emitting diode; a second transistor connected to said timer means and said first transistor; and a third transistor connected to said first and second transistors and having a terminal through which said power failure indicating signal is provided.
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7. A reserve power source for switchably providing an auxiliary power signal to a load when at least one of a plurality of conditions is detected in a primary power signal provided to the load from a primary power supply, said reserve power source comprising:
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auxiliary power means for providing said auxiliary power signal; switch means for connecting said primary power supply with said load when said switch means is in a first state and for disconnecting said primary power supply from said load when said switch means is in a second state; clock means for providing a periodic clock signal synchronized with a zero-crossing of said primary power signal; means for providing a switch control signal when said primary power signal has a magnitude which exceeds a magnitude threshold level, said means including; filter means for detecting when said primary power signal includes at least one frequency component greater than a frequency threshold; threshold setting means for setting said magnitude threshold level in response to said filter means and for comparing said magnitude of said primary power signal with said magnitude threshold level; and means, responsive to said clock means and said threshold setting means, for generating said switch control signal in synchronization with a zero-crossing of said primary power signal; and switch control means for placing said switch means in said second state in response to said switch control signal, thereby disconnecting said primary power supply from said load, and for enabling said auxiliary power means to provide said auxiliary power signal to said load in synchronization with a zero-crossing of said primary power signal. - View Dependent Claims (8, 9, 10, 18)
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11. A reserve power source for switchably providing an auxiliary power signal to a load when at least one of a plurality of conditions is detected in a primary power signal provided to the load from a primary power supply, said reserve power source comprising:
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auxiliary power means, connectible to said load, for providing said auxiliary power signal; switch means for connecting said primary power supply with said load when said switch means is in a first state and for disconnecting said primary power supply from said load when said switch means is in a second state; clock means for providing a periodic clock signal synchronized with zero-crossings of said primary power signal, said clock signal having two distinguishable portions within each cycle; first detector means for instantaneously detecting a first condition wherein the magnitude of said primary power signal is reduced substantially to zero, said first detector means including; means, connectible to said primary power supply, for generating a control pulse commencing whenever a predetermined magnitude of said primary power signal occurs prior to a respective zero-crossing of said primary power signal and terminating at least whenever a predetermined magnitude of said primary power signal occurs after said respective zero-crossing; and means, responsive to said clock signal and said control pulse, for providing a first switch control signal when at least a portion of said control pulse exists during at least a part of a predetermined one of said two distinguishable portions of said clock signal; second detector means for detecting a second condition wherein said primary power signal includes a magnitude above a first threshold value, said second detector means including means for providing a second switch control signal in synchronization with said clock signal; third detector means for detecting a third condition wherein the magnitude of said primary power signal is less than a second threshold value, said third detector means including means for providing a third switch control signal in synchronization with said clock signal; and switch control means for placing said switch means in said second state and for enabling said auxiliary power means in response to at least one of said first and second switch control signals so that said auxiliary power signal is provided to said load at a switchover time and for placing said switch means in said first state in response to at least one of said second and third switch control signals so that said primary power signal is provided to said load at a switchback time. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification