Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Frequency of cyclic current or voltage
Patent
1996-08-12
2000-05-09
Larkin, Daniel S.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Frequency of cyclic current or voltage
324 7641, 324166, 324177, 340648, 340658, G01R 2315, G01P 3481, G08B 2300
Patent
active
06060879&
ABSTRACT:
A current magnitude sensing circuit for detecting a malfunction of a DC brushless fan. The current magnitude sensing circuit detects drops in the current magnitude in windings of a fan motor. Depending on the frequency of the current drops in the fan current, the current magnitude sensing circuit outputs either a high or a low voltage signal. The current magnitude sensing circuit operates by charging a capacitor beyond a certain voltage and thereby providing a high fan fail output signal when a fan is spinning too slowly for proper cooling of a device. Another capacitor is charged at a different time constant for setting the fan fail output of the current magnitude circuit low for indicating that the fan is spinning sufficiently fast.
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"Brushless DC Motor Fault Detection Circuit" IBM Technical Disclosure Bulletin, vol. 37, No. 12 Dec. 1994, pp. 281-282 XP-002060283.
Comair Rotron, Inc., "DC Fan Performance Sensor (FPS)", Product Catalogue Fans, Blowers, Accessories, pp. 58-59, Cat. No.:COM8019 10M, .COPYRGT. May 1995.
Comair Rotron, Inc., "Tachometer Output Option", Product Catalogue Fans, Blowers, Accessories, pp. 60-61, Cat. No.:COM8019 10M, .COPYRGT. May 1995.
CORE Engineering, Inc., "Schematic Fan 1 & 2 Fail Sense", Internal Circuit Schematic for Fan Current Sensing Circuit dated Oct. 27, 1993.
CORE Engineering Inc.
Larkin Daniel S.
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