# US 2010/0169031 A1 · Apparatus, system, and method for precise early detection of ac power loss > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0169031 A1 - Document ID: US20100169031A1 - Status: Published application - Kind: A1 - Application number: 12/346,307 - Filed: 2008-12-30 - Published: 2010-07-01 - Earliest claimed: 2008-12-30 - Assignees: International Business Machines Corporation - Inventors: C. Charles Dishman; Jen-Ching Lin; Randhir S. Malik - Web page: https://patentgrep.com/patent/US20100169031A1 ## CPC - G01R 31/40: Testing power supplies (testing photovoltaic devices H02S50/10) - G06F 1/28: Supervision thereof, e.g. detecting power-supply failure by out of limits supervision - G06F 1/30: Means for acting in the event of power-supply failure or interruption, e.g. power-supply fluctuations (for resetting only G06F1/24) - G06F 1/305: {in the event of power-supply fluctuations} - G06F 11/2015: {Redundant power supplies (power supply failure G06F1/30)} - G06F 11/2038: {with a single idle spare processing component} - G06F 11/2046: {where the redundant components share persistent storage (G06F11/2043 takes precedence)} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract An apparatus, system, and method are disclosed for determining power source failure. A sampling module samples an alternating current power waveform as input to a power supply, at a sampling frequency which is a multiple of a predetermined frequency, to obtain a sampled amplitude at a known point within the predetermined period. A comparison module compares the sampled amplitude to a stored threshold amplitude to obtain a comparison result, corresponding to the known point. An accumulation module accumulates most recent comparison results. A warning module asserts an early power off warning signal if a predetermined number of the most recent comparison results each indicate that the sampled amplitude is smaller in absolute value than the stored threshold amplitude. ## Claims ### Claim 1 An apparatus for determining power source failure, the apparatus comprising: a power supply that receives an alternating current (“AC”) power waveform, the power waveform comprising a predetermined frequency and a corresponding predetermined period; a rectifier that rectifies the power waveform to yield a rectified power waveform; an analog-to-digital converter that samples the rectified power waveform, the sampling at a sampling frequency which is a multiple of the predetermined frequency, the sampling to obtain a sampled amplitude at a known point within the predetermined period; an initialization module that initializes a stored threshold amplitude corresponding to each known point within the predetermined period; a buffer module that buffers the sampled amplitude through a consecutive sequence of most recent sampled amplitudes; a comparison module that compares the sampled amplitude to the stored threshold amplitude to obtain a comparison result, the stored threshold amplitude corresponding to the known point within the predetermined period; an accumulation module that accumulates the most recent comparison results; and a warning module that asserts an early power off warning signal if a predetermined number of the most recent comparison results each indicate that the sampled amplitude is smaller in absolute value than the stored threshold amplitude. ### Claim 2 An apparatus for determining power source failure, the apparatus comprising: a sampling module that samples an alternating current (“AC”) power waveform, the power waveform comprising input to a power supply and comprising a predetermined frequency and a corresponding predetermined period, the sampling at a sampling frequency which is a multiple of the predetermined frequency, the sampling to obtain a sampled amplitude at a known point within the predetermined period; a comparison module that compares the sampled amplitude to a stored threshold amplitude to obtain a comparison result, the stored threshold amplitude corresponding to the known point within the predetermined period; an accumulation module that accumulates most recent comparison results; and a warning module that asserts an early power off warning signal if a predetermined number of the most recent comparison results each indicate that the sampled amplitude is smaller in absolute value than the stored threshold amplitude. ### Claim 3 (depends on 2) The apparatus of claim 2, further comprising an initialization module that initializes the stored threshold amplitude corresponding to each known point within the predetermined period, and calibrates the stored threshold amplitude as a predetermined percentage of the sampled amplitude at the known point within the predetermined period corresponding to the stored threshold amplitude. ### Claim 4 (depends on 2) The apparatus of claim 2, further comprising a recovery module that, in response to the early power off warning signal, performs one or more of saving data of a computer and suspending operation of the computer, the computer powered by the power supply that receives the power waveform. ### Claim 5 (depends on 2) The apparatus of claim 2, wherein the sampling module comprises a rectifier that rectifies the power waveform such that the sampled amplitude is in absolute value. ### Claim 6 (depends on 2) The apparatus of claim 2, further comprising a buffer module that buffers the sampled amplitude through a consecutive sequence of most recent sampled amplitudes for comparison with the stored threshold amplitude. ### Claim 7 (depends on 2) The apparatus of claim 2, further comprising: a power supply that receives the power waveform; and a computer powered by the power supply. ### Claim 8 (depends on 7) The apparatus of claim 7, further comprising a storage subsystem in which data of the computer is saved in response to the early power off warning signal. ### Claim 9 (depends on 7) The apparatus of claim 7, further comprising a backup computer that is activated in response to the early power off warning signal. ### Claim 10 (depends on 7) The apparatus of claim 7, wherein the power supply comprises a primary power supply and further comprising a backup power supply, wherein the backup power supply provides power to a load powered by the primary power supply in response to the early power off warning signal. ### Claim 11 A computer program product comprising a computer readable medium having computer usable program code executable to perform operations for determining power source failure, the operations of the computer program product comprising: sampling an alternating current (“AC”) power waveform, the power waveform comprising input to a switching power supply and comprising a predetermined frequency and a corresponding predetermined period, the sampling at a sampling frequency which is a multiple of the predetermined frequency, the sampling to obtain a sampled amplitude at a known point within the predetermined period; initializing a stored threshold amplitude corresponding to each known point within the predetermined period; buffering the sampled amplitude through a consecutive sequence of most recent sampled amplitudes; comparing the sampled amplitude to the stored threshold amplitude to obtain a comparison result, the stored threshold amplitude corresponding to the known point within the predetermined period; accumulating most recent comparison results; and asserting an early power off warning signal if a predetermined number of the most recent comparison results each indicate that the sampled amplitude is smaller in absolute value than the stored threshold amplitude. ### Claim 12 A machine-implemented method for determining power source failure, the method comprising: sampling an alternating current (“AC”) power waveform, the power waveform comprising input to a power supply and comprising a predetermined frequency and a corresponding predetermined period, the sampling at a sampling frequency which is a multiple of the predetermined frequency, the sampling to obtain a sampled amplitude at a known point within the predetermined period; comparing the sampled amplitude to a stored threshold amplitude to obtain a comparison result, the stored threshold amplitude corresponding to the known point within the predetermined period; accumulating most recent comparison results; and asserting an early power off warning signal if a predetermined number of the most recent comparison results each indicate that the sampled amplitude is smaller in absolute value than the stored threshold amplitude. ### Claim 13 (depends on 12) The method of claim 12, further comprising initializing the stored threshold amplitude corresponding to each known point within the predetermined period. ### Claim 14 (depends on 12) The method of claim 12, further comprising buffering the sampled amplitude through a consecutive sequence of most recent sampled amplitudes prior to comparing the sampled amplitude to a stored threshold amplitude. ### Claim 15 (depends on 12) The method of claim 12, further comprising calibrating the stored threshold amplitude as a predetermined percentage of the sampled amplitude at the known point within the predetermined period corresponding to the stored threshold amplitude. ### Claim 16 (depends on 15) The method of claim 15, wherein calibrating the stored threshold amplitude is performed at periodic intervals, wherein the stored threshold amplitude is stored in one of a plurality of storage areas for each successive interval. ### Claim 17 (depends on 12) The method of claim 12, further comprising saving data of a computer powered by a power supply that receives the power waveform in response to the early power off warning signal. ### Claim 18 (depends on 17) The method of claim 17, further comprising suspending operation of the computer n response to the early power off warning signal. ### Claim 19 (depends on 18) The method of claim 18, further comprising activating a backup computer in response to the early power off warning signal. ### Claim 20 (depends on 12) The method of claim 12, further comprising providing power to a load with a backup power supply in response to the early power off warning signal, the load connected to the power supply receiving the AC power waveform.