US Patent No: 4,231,029

Number of patents in Portfolio can not be more than 2000

Automatic transfer control device and frequency monitor

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Abstract

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An automatic transfer control device for generating signals to cause associated circuit interrupters to selectively energize an electrical distribution system from either of a pair of electrical power sources. The device includes an over- and under-frequency monitoring circuit to determine if the power source frequency is within preset limits. The frequency monitoring circuit includes a zero-crossing detector which activates a clock oscillator, the output pulses of which are accumulated by a counter for one half cycle. The number of pulses occurring during the half cycle is compared with a limit value stored in a read-only memory. An alarm signal is activated if the number of pulses accumulated is out of limits. The address inputs of the read-only memory are connected to the alarm signal generator and to a flip-flop toggled by the zero-crossing detector so that any of four limit values are selectively accessed for input to the comparator: high limit, low limit, return-to-normal after high alarm, and return-to-normal after low alarm. A strobe circuit is provided to only momentarily energize the read-only memory, thereby reducing power consumption.

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Patent Owner(s)

Patent OwnerAddressTotal Patents
WESTINGHOUSE ELECTRIC CORP.PITTSBURGH, PA4652

International Classification(s)

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Inventor(s)

Inventor Name Address # of filed Patents Total Citations
Johnston, Paul M Troy, MI 7 194

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Patent Info (Count) # Cites Year
 
AMERICAN POWER CONVERSION CORPORATION (8)
7,142,950 Methods and apparatus for providing and distributing standby power 28 2004
7,446,437 Apparatus and method for preventing an electrical backfeed 10 2005
7,418,314 Methods and apparatus for providing and distributing standby power 23 2006
7,983,797 Methods and apparatus for providing and distributing standby power 3 2008
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7,786,617 System and method for allocating power to loads 7 2009
RE43177 Apparatus and method for preventing an electrical backfeed 1 2010
8,521,336 Energy reduction 0 2012
 
Sundstrand Corporation (5)
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GENERAL ELECTRIC COMPANY (2)
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ASCO POWER TECHNOLOGIES, L.P. (1)
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AT&T INTELLECTUAL PROPERTY I, L.P. (1)
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ATMEL ROUSSET S.A.S. (1)
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INTERNATIONAL BUSINESS MACHINES CORPORATION (1)
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ONAN CORPORATION (1)
4,423,336 Electromechanically controlled automatic transfer switch and bypass switch assembly 49 1982
 
Scheider Electric IT Corporation (1)
8,446,040 System and method for allocating power to loads 0 2010
 
Westinghouse Electric Corp. (1)
4,672,227 Automatic transfer switch with delay 27 1986
 
Other [Check patent profile for assignment information] (2)
4,760,278 Transfer switch 40 1987
5,142,163 High speed load transfer system 17 1987