1. A power control apparatus comprising:
a transducer operable to detect a predefined parameter and generate an activation signal in response to said detection;
a switching device comprising an electrical input for connecting to an electrical supply, an electrical output for connecting to one or more electrical appliances, a switch connected between said electrical input and said electrical output, and fault sensing means arranged to actuate the switch to disconnect the electrical input from the electrical output when a fault is detected in the electrical supply drawn from the switching device by said appliance(s) from said electrical output; and
fault simulation means, remote from said transducer, arranged to simulate a fault in the supply drawn from said electrical output of said switching device in response to receiving said activation signal from said transducer, so as to actuate the switch to disconnect the electrical input from the electrical output.
2. A power control apparatus as claimed in claim 1, in which said transducer is a switch and wherein activation of said switch causes the generation of said activation signal.
3. A power control apparatus as claimed in claim 1, in which said predefined parameter is selected from the group including heat, smoke, carbon monoxide, and carbon dioxide.
4. A power control apparatus as claimed in claim 3, in which said activation signal is an acoustic signal and wherein said fault simulation means further comprises a sensor operable to detect said acoustic signal, wherein said fault simulation means is arranged to simulate said fault in said supply in response to said sensor detecting said acoustic signal.
5. A power control apparatus as claimed in claim 1, in which the switching device further comprises a mains circuit breaker arranged to disconnect the electrical input from the electrical output.
6. A power control apparatus as claimed in claim 1, in which the switching device further comprises a residual current device arranged to disconnect the electrical input from the electrical output when an imbalance is detected in the current flowing along a pair of wires across which the or each appliance is connected.
7. A power control apparatus as claimed in claim 1, in which the electrical input of the switching device comprises first and second input terminals respectively connected to first and second output terminals of the electrical output, said switch being disposed between the first input terminal and the first output terminal, and wherein said fault simulation means is arranged to connect a load between the first output terminal and the second input terminal or between the second output terminal and the first input terminal.
8. A power control apparatus as claimed in claim 7, in which the first and second input terminals are respectively arranged for connecting to the live and neutral of a mains supply.
9. A power control apparatus as claimed in claim 1, in which the transducer is arranged to produce an audible output signal when operated.
10. A power control apparatus as claimed in claim 1, in which said fault simulation means is arranged to simulate a fault in the supply drawn from said electrical output of said switching device, the fault occurring a predetermined time period after said transducer activation signal is detected.
11. A power control apparatus as claimed in claim 10, comprising means for setting the time period.
12. A power control apparatus as claimed in claim 11, wherein said means for setting the time period comprises a device selected from the group including a clock, a timer switch, and a daylight sensor.
13. A power control apparatus as claimed in claim 1, in which the switching device and the fault simulation means are separate and are mounted inside a unit arranged to distribute an electrical supply to one or more appliance circuits via respective switching devices.
14. A power control apparatus as claimed in claim 13, comprising a plurality of switching devices mounted inside said unit feeding respective appliance circuits, said fault simulation means being arranged to simulate a fault in the supply drawn from the electrical output of at least one of said switching devices.
15. A power control apparatus as claimed in claim 14, in which said fault simulation means is arranged to simulate a plurality of faults in the supply drawn from the respective electrical outputs of each switching device, the plurality of faults occurring at different predetermined time periods after said transducer is operated.
16. A power control apparatus as claimed in claim 14, in which said fault simulation means comprises a plurality of fault simulation devices controlling respective switching devices.
17. (canceled)
18. A power control apparatus as claimed in claim 1, in which the transducer is arranged to transmit said activation signal to said fault simulation means via a signaling interface comprising one of a signal cable, a modulated signal on the mains wiring, a wireless data link, and an audio signal.
19. A power control apparatus as claimed in claim 1, in which said fault simulation means is arranged to simulate a fault in the supply drawn from said electrical output of said switching device upon receipt of an activation signal from said transducer or from a control unit to which said transducer is connected.
20. A power control apparatus as claimed in claim 19, in which said fault simulation means is addressable and is arranged to simulate a fault in the supply drawn from said electrical output of said switching device upon receipt of an addressed control signal from said transducer or from a control unit to which said transducer is connected, via a signaling interface comprising one of a signal cable, a modulated signal on the mains wiring, and a wireless data link.
21. A power control apparatus as claimed in claim 1, in which one or more gas control valves are connected to the electrical output(s) of said switching device, where said one or more gas control valves are operable to shut off gas supply to said one or more electrical appliances when said switching device disconnects the electrical input from the electrical output.
22. A power control apparatus as claimed in claim 1, wherein said fault simulation means further comprises control means operable to receive an external control signal wherein, in response to receiving said external control signal, said fault simulation means is arranged to either:
disregard the activation signal from said transducer if it is not already receiving said activation signal, such that it does not simulate a fault in the supply if it subsequently receives said activation signal; or
cease to simulate a fault on the supply if it is already receiving the activation signal.
23. A power control apparatus as claimed in claim 22, wherein said external control signal contains a unique address or otherwise and is received via a signaling interface comprising one of a signal cable, a modulated signal on the mains wiring, and a wireless RF link.
24. A fault simulation device arranged to control a switching device having fault sensing means for disconnecting a supply from an electrical output thereof when a fault is detected in the supply drawn by an appliance from said electrical output, wherein the fault simulation device comprises an input for receiving or detecting an alarm signal and means for simulating a fault in the supply drawn from the electrical output of the switching device when said alarm signal is received or detected.
25. A fault simulation device as claimed in claim 24, in which the switching device comprises a residual current device arranged to disconnect the electrical output when an imbalance is detected in the current flowing through first and second terminals of said electrical output across which the appliance is connected, wherein said fault simulation means is arranged to connect a load device to said first terminal which creates a current flow path to a point remote from said second output terminal.
26. A fault simulation device as claimed in claim 25, in which the load device comprises a resistor.
27. A fault simulation device as claimed in claim 25, in which the load device is only connected for a predetermined time to create said current flow path to said point remote from said second output terminal.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A float switch system for limiting to desirable levels current and energy entering a tank of combustible liquid, said system comprising:
a float switch disposed within said tank;
an interface circuit external to said tank and coupled through wiring to said float switch;
a passive transient suppression circuit coupled to said wiring external and in proximity to said tank, and operative to limit current and energy entering said tank over said wiring to the desirable levels; and
a control circuit coupled to said float switch through said transient suppression circuit and to said interface circuit, said control circuit operative to monitor the status of said float switch with current within the desirable current level and to energize said interface circuit based on said switch status.
2. The system of claim 1 wherein the interface circuit is rendered energized with current greater than the desirable current level.
3. The system of claim 1 wherein the interface circuit is disposed a substantial distance from the transient suppression circuit over wiring that is exposed to potential short duration and sustained threats; and wherein the transient suppression circuit is operative to maintain current and energy to the tank over the wiring to within the desirable levels notwithstanding a coupling of any one of said threats to the exposed wiring.
4. The system of claim 3 wherein the control circuit is disposed in proximity to the transient suppression circuit.
5. The system of claim 4 wherein the control circuit comprises a first circuit coupled to the float switch through the transient suppression circuit for monitoring the status of the float switch with current limited by an impedance of the transient suppression circuit; and a second circuit including a switch circuit controlled by the first circuit to energize the interface circuit based on said monitored status.
6. The system of claim 5 wherein the first circuit comprises a pair of current mirror circuits for monitoring the status of the float switch.
7. The system of claim 5 wherein the second circuit comprises both a high side drive connection and a low side drive connection.
8. The system of claim 5 wherein the switch circuit comprises a solid-state switch driven by the first circuit.
9. The system of claim 5 wherein the passive transient suppression circuit comprises a resistor network; and wherein the first circuit is coupled to a ground connection through the resistor network and float switch.
10. The system of claim 9 wherein the passive transient suppression circuit comprises capacitance coupled from said resistor network to the ground connection.
11. The system of claim 3 wherein the control circuit is disposed in proximity to the interface circuit and coupled to the passive transient suppression circuit over the exposed wiring.
12. The system of claim 11 wherein the control circuit comprises an electro-mechanical device coupled to the float switch through the exposed wiring and transient suppression circuit, said electromechanical device including a contact responsive to the status of the float switch for energizing the interface circuit.
13. The system of claim 12 wherein the contact rendering an electrical isolation between the exposed wiring and the interface circuit.
14. The system of claim 13 wherein the electro-mechanical device comprises a relay responsive to the status of the float switch and energized by a current within the desirable current level.
15. The system of claim 14 wherein the energization current of the relay is limited by an impedance of the transient suppression circuit; and wherein the relay is operative notwithstanding a voltage drop across the transient suppression circuit resulting from the energization current.
16. The system of claim 11 wherein the control circuit comprises a first circuit coupled to the float switch through the exposed wiring and transient suppression circuit for monitoring the status of the float switch with current limited by an impedance of the transient suppression circuit; and a second circuit including a switch circuit controlled by the first circuit to energize the interface circuit based on said monitored status.
17. The system of claim 16 wherein the first circuit comprises a pair of current mirror circuits for monitoring the status of the float switch.
18. The system of claim 16 wherein the switch circuit comprises a solid-state switch driven by the first circuit.
19. The system of claim 16 wherein the passive transient suppression circuit comprises a resistor network; and wherein the first circuit is coupled to a ground connection through the exposed wiring, resistor network and float switch.
20. The system of claim 19 wherein the passive transient suppression circuit comprises capacitance coupled from said resistor network to the ground connection.
21. The system of claim 1 wherein the control circuit comprises a voltage limiting circuit for protecting the circuitry of the control circuit from short duration threats.
22. The system of claim 21 wherein the voltage limiting circuit comprises voltage transient suppression and capacitive elements.
23. The system of claim 1 wherein the float switch system is disposed on an aircraft for limiting to desirable levels the current and energy entering a fuel tank of said aircraft.
24. The system of claim 23 wherein the interface circuit comprises any one of the group consisting of a fuel control valve, a fuel transfer valve, a relay, a solenoid, and a fuel level indicator.
25. The system of claim 23 wherein the interface circuit is disposed a substantial distance from the transient suppression circuit over wiring that is exposed to potential short duration and sustained threats; and wherein the transient suppression circuit is operative to maintain current and energy to the fuel tank over the exposed wiring to within the desirable levels notwithstanding a coupling of any one of said threats to the exposed wiring.
26. The system of claim 25 wherein the control circuit is disposed in proximity to the interface circuit and coupled to the passive transient suppression circuit at the fuel tank over existing aircraft wiring.
27. The system of claim 26 wherein the passive transient suppression circuit comprises a resistor network; and wherein the control circuit is coupled to a ground connection at the fuel tank through the exposed wiring, the passive transient suppression circuit and float switch.