US 6,297,569 B1Granted

Power switching system

AssigneeHoneywell International Inc.

InventorsJames I. Bartels, Robert D. Juntunen, Paul B. Patton, Richard M. Solosky

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Abstract

A power controller has upstream and downstream switches in series connection to provide redundant switching for power supplied from a power source to a load. A switch operating system closes the switch closer to the load first (downstream) and then the switch closer to the source (upstream). The operating system conditions closing the downstream switch on absence of power voltage on an upstream power terminal of the downstream switch. A preferred embodiment of the operating system performs a number of real time status checks during the connection process to assure that power voltage is properly absent and present at switch terminals during the stages of the connection process. This operating system guards against supplying power to the load if either the upstream or downstream switch's pair of contacts are welded at the time the connection process starts.

Claims21

Dependent claims

In a power connection system for supplying power to a load during a demand interval defined by a predetermined value of a demand signal, said connection system having i) a first electrically controlled switch having first and second power terminals, and a first control terminal for receiving a first connect signal, and responsive thereto establishing electrical contact between the first switch's first and second power terminals, and ii) a second electrically controlled switch having first and second power terminals, and a second control terminal for receiving a second connect signal, and responsive thereto establishing electrical contact between the second switch's first and second power terminals, said first switch's first power terminal for connection to a power source, said first switch's second power terminal and said second switch's first power terminal in electrical connection, and said second switch's second power terminal for connection to the load, a switch operating system comprising:

a) a first voltage sensor having a sensor terminal connected to the first switch's second power terminal, and providing at a signal terminal a first power signal having a first value responsive to power voltage present at the sensor terminal and having a second value otherwise;
b) a switch status detector receiving the first power signal and the demand signal, and responsive to the start of the demand interval and the second value of the first power signal, providing a first status signal having a second value, and a first value otherwise;
and
c) a switch controller receiving the first status signal and responsive to the second value thereof, providing the second connect signal to the second control terminal and after a first preselected interval, providing the first connect signal to the first control terminal.

1 more element

A method for ensuring fail-safe control of electric current supplied to a load from a source through first and second switches connected in series between the source and the load, the first and second switches each having first and second power terminals of which the first power terminal of the first switch is connected to the source, the second power terminal of the first switch and the first power terminal of the second switch are connected together, and the second power terminal of the second switch is connected to the load, the first and second switches each normally responsive to closing and opening commands to respectively (i) establish electrical continuity between its first and second power terminals and (ii) break electrical continuity between its first and second power terminals, the method, upon desired energization of the load, comprising the steps of:

performing a first check of voltages at the second power terminals of the first and second switches;
if voltages no greater than a reference voltage are found during the first check, providing a first closing command to the first switch;
performing a second check of voltages at the second power terminals of the first and second switches;
if a voltage greater than the reference voltage is found at the second power terminal of the first switch and a voltage no greater than the reference voltage is found at the second power terminal of the second switch during the second check, providing a first opening command to the first switch;
performing a third check of voltages at the second power terminals of the first and second switches;
if voltages no greater than the reference voltage are found during the third check, providing a first closing command to the second switch;
and
after providing the first closing command to the second switch, providing a second closing command to the first switch.

5 more elements

Dependencies are inferred from the claim text.