US4696785A — Testable voted logic power circuit and method of …

Claim 1

Independent Claim 226 words

A testable two out of three voted power circuit for the protection system of a complex process control system comprising: a load; a voltage source; three pairs of switches connected in three groups of two switches each with the two switches in each group associated with a different pair of switches and being connected in parallel, and with the three groups of switches being connected in series with each other, and with the load across the voltage source; means for generating three independent actuating signals; means for applying a different one of said actuating signals independently to one of said pairs of switches to actuate the same, and thereby actuate the load device only if at least two out of the three actuating signals are generated; a resistor shunting each group of switches to provide a leakage path between the voltage source and the load device; and a current detector for measuring the current drawn from the voltage source, the impedance of said resistors being several magnitudes larger than the impedance of a closed switch such that the current through the leakage path is insufficient to energize the load but sufficient for the current measuring means to detect whether a switch is actuated, whereby the operation of the switches can be tested without actuating the load device by separately generating one actuating signal at a time.

Claim 2

Dependent Claim 226 words

A testable two out of three voted power circuit for the protection system of a complex process control system comprising: a load; a voltage source; three pairs of switches connected in three groups of two switches each with the two switches in each group associated with a different pair of switches and being connected in parallel, and with the three groups of switches being connected in series with each other, and with the load across the voltage source; means for generating three independent actuating signals; means for applying a different one of said actuating signals independently to one of said pairs of switches to actuate the same, and thereby actuate the load device only if at least two out of the three actuating signals are generated; a resistor shunting each group of switches to provide a leakage path between the voltage source and the load device; and a current detector for measuring the current drawn from the voltage source, the impedance of said resistors being several magnitudes larger than the impedance of a closed switch such that the current through the leakage path is insufficient to energize the load but sufficient for the current measuring means to detect whether a switch is actuated, whereby the operation of the switches can be tested without actuating the load device by separately generating one actuating signal at a time.

Claim 3

Dependent Claim 54 words

The power circuit of claim 1 wherein said load is a normally energized device and wherein the switches are normally closed devices which are open when actuated by the associated actuation signal, such that the load is normally energized and is deenergized by the generation of at least two out of three actuation signals.

Claim 4

Dependent Claim 46 words

The power circuit of claim 1 wherein said switches are normally open devices which are closed when actuated by the associated actuation signal, such that the load is normally deenergized but is energized by the generation of at least two out of the three actuation signals.

Claim 5

Dependent Claim 243 words

A protection system for a nuclear reactor comprising: redundant sets of detectors for monitoring preselected reactor parameters and operating conditions and for generating redundant partial actuation signals in response to preselected values and conditions; three independent logic trains, to each of which each redundant partial actuation signal is applied, said logic trains each generating an actuation signal in response to a preselected number of the redundant partial actuation signals; a load; a voltage source; three pairs of switches connected in three groups of two switches each with the two switches in each group associated with a different pair of switches and being connected in parallel, and with the three groups of switches being connected in series with each other and with the load across the voltage source; means for applying a different one of said actuating signals independently to each of said pairs of switches to actuate the same, and thereby actuate the load when at least two out of the three actuation signals are generated; a resistor shunting each group of switches to provide a leakage path between the voltage source and the load device; and a current detector for measuring the current drawn from the voltage source, the impedance of said resistors being several magnitudes larger than the impedance of a closed switch, such that the current through the leakage path is insufficient to energize the load, but sufficient for the current measuring means to detect whether a switch is actuated.

Claim 6

Dependent Claim 243 words

A protection system for a nuclear reactor comprising: redundant sets of detectors for monitoring preselected reactor parameters and operating conditions and for generating redundant partial actuation signals in response to preselected values and conditions; three independent logic trains, to each of which each redundant partial actuation signal is applied, said logic trains each generating an actuation signal in response to a preselected number of the redundant partial actuation signals; a load; a voltage source; three pairs of switches connected in three groups of two switches each with the two switches in each group associated with a different pair of switches and being connected in parallel, and with the three groups of switches being connected in series with each other and with the load across the voltage source; means for applying a different one of said actuating signals independently to each of said pairs of switches to actuate the same, and thereby actuate the load when at least two out of the three actuation signals are generated; a resistor shunting each group of switches to provide a leakage path between the voltage source and the load device; and a current detector for measuring the current drawn from the voltage source, the impedance of said resistors being several magnitudes larger than the impedance of a closed switch, such that the current through the leakage path is insufficient to energize the load, but sufficient for the current measuring means to detect whether a switch is actuated.

Claim 7

Dependent Claim 29 words

The system of claim 4 wherein the load is a normally deenergized device and the switches are normally open and are closed when actuated by the associated actuation signal.

Claim 8

Dependent Claim 29 words

The system of claim 4 wherein the load is a normally energized device and the switches are normally closed and are opened when actuated by the associated actuation signal.

Claim 9

Dependent Claim 167 words

In combination, a load, a voltage source, and a switching network connected in series with the load across the voltage source, said switching network including at least two switches both of which must be actuated to operate the load, the improvement comprising test means for testing said switches without actuating said load and comprising resistance means shunting each switch and being connected in series with the load and voltage source to provide a leakage path across the switching network; current measuring means to measure the current drawn from the voltage source, said resistance means having an impedance several magnitudes larger then the impedance of a closed one of said switches such that the leakage current is insufficient to energize the load but sufficient for the current measuring means to detect whether a switch is actuated; and means to actuate one of said switches at a time to effect a change in the current detected by the current detector when said actuated switch operates without actuating said load.

Claim 10

Dependent Claim 167 words

In combination, a load, a voltage source, and a switching network connected in series with the load across the voltage source, said switching network including at least two switches both of which must be actuated to operate the load, the improvement comprising test means for testing said switches without actuating said load and comprising resistance means shunting each switch and being connected in series with the load and voltage source to provide a leakage path across the switching network; current measuring means to measure the current drawn from the voltage source, said resistance means having an impedance several magnitudes larger then the impedance of a closed one of said switches such that the leakage current is insufficient to energize the load but sufficient for the current measuring means to detect whether a switch is actuated; and means to actuate one of said switches at a time to effect a change in the current detected by the current detector when said actuated switch operates without actuating said load.

Claim 11

Dependent Claim 121 words

The combination of claim 7 wherein said network comprises m sets of switches arranged in a plurality of groups of switches with each groups of switches connected in series with the other groups and said load across said voltage source, each said group of switches comprising a different selection of n switches connected in parallel, each from a different one of said m sets of switches, said plurality of groups of switches comprising all possible different combinations of switches from said m sets taken n at a time, such that with at least n out of said m sets of switches actuated the load is actuated, and said resistance means comprises a resistor shunting the switches in each group of switches.

Claim 12

Dependent Claim 25 words

The combination of claim 8 wherein said load is a normally deenergized device and said switches are normally open devices which are closed when actuated.

Claim 13

Dependent Claim 25 words

The combination of claim 8 wherein said load is a normally energized device and said switches are normally closed devices which are opened when actuated.

Claim 14

Independent Claim 191 words

A method of testing a power circuit for a protection system in a complex process control system without interrupting the protection function where the power circuit includes m sets of switches arranged in a plurality of groups of switches with each group of switches connected in series with the other groups and with a load across a voltage source, each group of switches comprising a different selection of n switches connected in parallel each from a different one of said m sets of switches, such that with at least n out of said m sets of switches actuated the load is actuated, said method comprising the steps of: shunting each of said groups of switches with a resistor to form a leakage path through said arrangement of switches, the resistance of said resistors being several magnitudes larger than that of a closed switch, such that the current through the leakage path is insufficient to actuate the load but sufficient to be measurably changed by actuation of a switch; actuating one of said m sets of switches; and measuring the effect such actuation has on the current drawn from the voltage source.

Claim 15

Independent Claim 191 words

A method of testing a power circuit for a protection system in a complex process control system without interrupting the protection function where the power circuit includes m sets of switches arranged in a plurality of groups of switches with each group of switches connected in series with the other groups and with a load across a voltage source, each group of switches comprising a different selection of n switches connected in parallel each from a different one of said m sets of switches, such that with at least n out of said m sets of switches actuated the load is actuated, said method comprising the steps of: shunting each of said groups of switches with a resistor to form a leakage path through said arrangement of switches, the resistance of said resistors being several magnitudes larger than that of a closed switch, such that the current through the leakage path is insufficient to actuate the load but sufficient to be measurably changed by actuation of a switch; actuating one of said m sets of switches; and measuring the effect such actuation has on the current drawn from the voltage source.

Claim 16

Dependent Claim 72 words

The method of claim 11 including determining the current drawn from the voltage source for predetermined patterns of actuation of said switches during operation of said protection system, monitoring the current drawn from the voltage source, and comparing the monitored current with the current determined for the existing pattern of actuation of said switches to determine whether all of the switches have been actuated in accordance with the existing pattern of actuation.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1990-09-28	1991-03-30	1991-09-29	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1994-09-28	1995-03-30	1995-09-29	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1998-09-28	1999-03-30	1999-09-29	$7700.00	Window Closed / Lapsed

Testable voted logic power circuit and method of testing the same

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