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Title:
FIRE DETECTION AND PREVENTION SYSTEM AND METHOD
Document Type and Number:
WIPO Patent Application WO/2019/017797
Kind Code:
A1
Abstract:
A fire detection and prevention system (1) and method comprising a processor (11), a switch (13) controlled by the processor (11), and a power supply (14) configured to be connected to a mains sub-circuit (100) protected with a residual-current device (RCD) (110), wherein the power supply (14) provides power to the processor (11), wherein; the switch (13) is connected between a live phase (101, 102) and an earth wire (103) of the mains sub-circuit (100), and is in a normal open position, and wherein the processor (11) is configured to simulate a time-limited earth failure by operating the switch (13) and providing a time-limited connection between the live phase (101, 102) and the earth wire (103) when a fire alarm signal is received from the wireless fire detection sensor (3).

Inventors:
IVERSEN, Reidar August (Myrdalsvegen 8B, 5131 NYBORG, 5131, NO)
Application Number:
NO2018/050194
Publication Date:
January 24, 2019
Filing Date:
July 18, 2018
Export Citation:
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Assignee:
PRAESIDIO TOTALIS AS (Hagellia 6, 5914 ISDALSTØ, 5914, NO)
International Classes:
G08B17/00; G08B17/10; H02H3/16; H02H5/04
Domestic Patent References:
WO2014204488A12014-12-24
WO2007143576A22007-12-13
Foreign References:
US8450879B22013-05-28
US20150077243A12015-03-19
EP3035472A12016-06-22
Attorney, Agent or Firm:
ZACCO NORWAY AS (P.O.Box 2003 Vika, 0125 OSLO, 0125, NO)
Download PDF:
Claims:
CLAIMS

1. A fire detection and prevention system (1) comprising;

a controller (10) comprising;

- a processor (11),

- a switch (13) controlled by the processor (11), and

- a power supply (14) configured to be connected to a mains sub-circuit (100) protected with a residual-current device (RCD) (110), wherein the power supply (14) provides power to the processor (11), wherein;

the switch (13) is connected between a live phase (101, 102) and an earth wire (103) of the mains sub-circuit (100), and is in a normal open position, and wherein the processor (11) is configured to simulate a time-limited earth failure by operating the switch (13) and providing a time-limited connection between the live phase (101, 102) and the earth wire (103) when a fire alarm signal is received from the wireless fire detection sensor (3).

2. The fire detection and prevention system (1) according to claim 1, comprising a wireless interface (12), wherein the power supply (11) provides power to the wireless interface (12), and a wireless fire detection sensor (3) configured to detect a fire and send a fire alarm signal via the wireless interface (12) to the processor (11),

3. The fire detection and prevention system (1) according to claim 1, comprising a wired interface (17), and a wired fire detection sensor (31) configured to detect a fire and send a fire alarm signal via the wired interface (17) to the processor (11),

4. The fire detection and prevention system (1) according to any of the claims above, wherein the controller (10) is arranged in a housing (2) configured to be arranged in a mains electric outlet box (120).

5. The fire detection and prevention system (1) according to any of the claims above, wherein the controller (10) comprises a temperature sensor (15) arranged to measure a temperature in the surrounding of the housing (2), wherein the temperature sensor (15) is connected to the processor (11) and wherein the processor (11) is configured to simulate the time-limited earth failure when the temperature exceeds a pre-defined temperature.

6. The fire detection and prevention system (1) according to any of the claims above, wherein the current through the time limited connection is limited by a resistor (16) connected in series with the switch (13).

7. The fire detection and prevention system (1) according to claim 6, wherein the current through the time limited connection is limited to 20, 30, 40, 50 or 100 mA.

8. The fire detection and prevention system (1) according to any of the claims above, wherein the time limited connection is below 10, 5, 3, 2 or 1 seconds.

9. The fire detection and prevention system (1) according to any of the claims above, wherein the processor (11) is configured to repeatedly simulate the time-limited earth failure according to pre-defined time intervals to test the RCD.

10. The fire detection and prevention system (1) according to any of the claims above, where the controller (10) comprises;

- an alarm output interface (18) and

- a voltage sensor (19) connected to the mains sub-circuit (100), wherein

the processor (11) is configured to detect the voltage from the voltage sensor (19) after the time-limited earth failure has been simulated and to activate the alarm output interface (18) if the mains voltage is still above a pre-defined value.

11. The fire detection and prevention system (1) according to claim 10, wherein the alarm output interface (18) is connected to an audible alarm unit (31).

12. The fire detection and prevention system (1) according to claim 10, wherein the alarm output interface (18) is connected to a visible alarm unit.

13. A method for fire detection and prevention comprising the steps of;

- detecting a fire with fire detection sensor (3),

- transmitting a fire alarm signal from the fire detection sensor (3) to a controller (10) arranged in a mains electric outlet box (120),

- simulate a time-limited earth failure by operating a switch (13), which is in a normal open position and connected between a live phase (101) and an earth wire (103) of a mains sub- circuit (100) of the mains electric outlet box (120), from the controller (10) to provide a time- limited connection between the live phase (101) and the earth wire (103).

14. The method for fire detection and prevention of claim 13, wherein the fire detection sensor (3) is wireless and the fire alarm signal from the fire detection sensor (3) to the controller (10) arranged in a mains electric outlet box (120) is transmitted wirelessly.

15. The method for fire detection and prevention of claim 13, wherein the fire detection sensor (3) is wired and the fire alarm signal from the fire detection sensor (3) to the controller (10) arranged in a mains electric outlet box (120) is transmitted over a wired connection,

16. The method for fire detection and prevention according to any of the claims 13 to 15, comprising the steps of;

- repeatedly simulating the time-limited earth failure according to pre-defined time intervals,

- detecting the voltage from the voltage sensor (19) after the time-limited earth failure has been simulated and

- activating the alarm output interface (18) if the mains voltage is still above a pre-defined value.

17. The method of fire detection and prevention according to any of the claims 13 to 16 above, wherein the time limited connection is below 10, 5, 3, 2 or 1 seconds.

Description:
FIRE DETECTION AND PREVENTION SYSTEM AND METHOD

TECHNICAL FIELD

[0001] The present invention relates to a fire detection and prevention system especially directed to fires caused by electric appliances connected to a mains sub-circuit, and systems and methods for detecting abnormal situations and shutting down the sub-circuit to extinguish or prevent escalation of the fire.

BACKGROUND

[0002] As electric appliances of different types become more and more abundant in homes and businesses, fires related to such appliances is increasing. One such cause of fire can be broken cables to chargers, the chargers themselves being faulty or failures in higher energy consumption appliances, such as stoves or heaters.

[0003] Common to all these electric failures, is that they may develop rapidly into critical fires that may lead to both huge material damages and even human casualties.

[0004] However, in the initial phase the fire is fueled by the electrical power provided from the mains. If the electric power can be shut down in the initial phase, many of these fires may simply extinguish and the damages will be limited.

[0005] International publication W09933155 discloses a method and system for protection of an electrical installation against series fault. The method comprises detection of heat development at specific points in the installation by means of individual sensor/switch units connected to the installation and interruption of the current supply to the installation when the heat development exceeds a given threshold.

[0006] Upon detection of abnormal heat development in one such specific point, the fault point will be connected to earth. This will result in an earth fault and interruption of the current supply to the installation will be effected by means of an earth leakage circuit breaker arranged between the installation and the connected current supply.

[0007] However, an earth fault in a live system has the serious negative effect that appliances may become dangerous if touched. Due to poor maintenance and lack of scheduled testing, such earth leakage circuit breakers do not always work properly, and what should have been a resolution to a potential problem, may then lead to a much more serious problem where the heat continues to develop into a fire and in addition the electric appliances become dangerous to touch.

[0008] In general, simulation of earth faults will therefore not be accepted by the authorities responsible for civil protection and utilities. [0009] There is a need for a system that solves the above mentioned problem in a way that allows easy shut-down of electric circuits related to a detected heat or fire. Preferably the system should be able to retrofit into existing infrastructure of buildings to help promote introduction of such safety systems.

SHORT SUMMARY

[00010] A goal with the present invention is to overcome the problems of prior art.

[00011] The invention solving the above mentioned problems is a fire detection and prevention system (1) comprising a controller (10) comprising;

- a processor (11),

- a switch (13) controlled by the processor (11), and

- a power supply (14) configured to be connected to a mains sub-circuit (100) protected with a residual-current device (RCD) (110), wherein the power supply (14) provides power to the processor (11), wherein;

the switch (13) is connected between a live phase (101, 102) and an earth wire (103) of the mains sub-circuit (100), and is in a normal open position, and wherein the processor (11) is configured to simulate a time-limited earth failure by operating the switch (13) and providing a time-limited connection between the live phase (101, 102) and the earth wire (103) when a fire alarm signal is received from the wireless fire detection sensor (3)..

The invention is also a method for method for fire detection and prevention comprising the steps of;

- detecting a fire with fire detection sensor (3),

- transmitting a fire alarm signal from the fire detection sensor (3) to a controller (10) arranged in a mains electric outlet box (120),

- simulate a time-limited earth failure by operating a switch (13), which is in a normal open position and connected between a live phase (101) and an earth wire (103) of a mains sub- circuit (100) of the mains electric outlet box (120), from the controller (10) to provide a time- limited connection between the live phase (101) and the earth wire (103).

[00012] An advantage, which is related to the above, is the re-use of the residual-current device for the purpose of fire detection and prevention, which has not been possible with prior art systems.

[00013] With the time-limited simulated earth failure resulting from an alarm condition, current can be broken without introducing potential hazardous electrical voltages and aggravating the already critical situation.

[00014] According to an embodiment, the invention comprises a wireless interface, wherein the power supply provides power to the wireless interface, and a wireless fire detection sensor configured to detect a fire and send a fire alarm signal via the wireless interface to the processor. An advantage related to this is that no additional infrastructure is necessary in existing buildings with already established mains and sub-circuits other than mounting and connecting the controller in an existing mains electric outlet box, in addition to mounting the fire detection alarm in wireless distance from the controller. Thus, a considerable

improvement in safety can be obtained for a limited installation cost.

[00015] According to an embodiment, the invention comprises a wired interface, and a wired fire detection sensor (3) configured to detect a fire and send a fire alarm signal via the wired interface to the processor (11). This can be advantageous in new installations and other installations where wired infrastructure can be easily established.

[00016] In an embodiment, the system has a combination of wired and wireless interfaces.

[00017] The invention in its various embodiments has further advantages, which will become apparent from the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[00018] Fig. 1 illustrates in a schematic drawing an embodiment of the invention

[00019] Fig. 2 illustrates how the controller (10) according to an embodiment may be installed in standard outlet box of an electrical wiring system.

EMBODIMENTS OF THE INVENTION

[00020] In the following description, various examples and embodiments of the invention are set forth in order to provide the skilled person with a more thorough understanding of the invention. The specific details described in the context of the various embodiments and with reference to the attached drawings are not intended to be construed as limitations. Rather, the scope of the invention is defined in the appended claims.

[00021] In an embodiment the fire detection and prevention system (1) comprises, as illustrated in Fig. 1, a controller (10). The controller comprises the main components of the system, which are; a processor (11), a wireless interface (12), a wired interface (17) a switch (13) controlled by the processor (10), and a power supply (14).

[00022] The system can have one or more wireless interfaces (12), one or more wired interfaces (17) or a combination of wireless (12) and wired (17) interfaces.

[00023] The power supply (14) is configured to be connected to a mains sub-circuit (100). The sub-circuit should be protected with a residual-current device (RCD) (110), as illustrated in Fig. 2. If the sub-circuit does not have an RCD, it should be installed before enabling the fire detection and prevention system (1).

[00024] The power supply (14) provides power to e.g. the processor (11) and the wireless interface (12).

[00025] The fire detection and prevention system (1) further comprises a wireless fire detection sensor (3) and a wired fire detection sensor (31) configured to detect a fire and send a fire alarm signal via the wireless interface (12) and wired interface 17, respectively, to the processor (11).

[00026] The switch (13) is connected between a live phase (101) and an earth wire (103) of the mains sub-circuit (100), and is in a normal open position, and wherein the processor (11) is configured to simulate a time-limited earth failure by operating the switch (13) and providing a time-limited connection between the live phase (101, 102) and the earth wire (103) when a fire alarm signal is received from the wireless fire detection sensor (3).

[00027] Outlet boxes (120) are commonly used in concealed conduit wiring systems, and also for surface mounted wires. Outlet boxes are therefore an existing part of the infrastructure of a building that may be reused for the purpose of the invention. Outlet boxes are typically used in walls for sockets, e.g. for stoves in kitchen or general sockets for all types of electric equipment, or lamp outlets. Outlet boxes are also as lamp outlets in roofs. For the purpose of the invention, the outlet box should have a cabling with both live wires (101, 102) and an earth wire (103).

[00028] In an embodiment, that may be combined with the embodiment above, the controller (10) is arranged in a housing (2) configured to be arranged in a mains electric outlet box (120) as illustrated in Fig. 2. Additional space should be left in the outlet box (2) to allow wiring and wiring connectors to local and remote receptacles (130).

[00029] As can be understood from Fig. 2, the wires from the controller (10) can simply be connected to the corresponding wires (101, 102) and an earth wire (103) in the electric outlet box (120). Typically the connectors of the receptacle (130), or other electric device attached to the outlet box have additional connectors that may be used for this purpose. Additional wiring connectors may also be used. The fire detection and prevention system (1) is then ready to use as soon as the wireless fire detection sensor (3) has been installed in the proximity, i.e. within wireless reach.

[00030] In an embodiment, that may be combined with any of the embodiments above, the controller (10) comprises a temperature sensor (15) arranged to measure a temperature in the surrounding of the housing (2), wherein the temperature sensor (15) is connected to the processor (11) and wherein the processor (11) is configured to simulate the time-limited earth failure when the temperature exceeds a pre-defined temperature. The sensor is illustrated in Fig. 1. It may be implemented in the housing (2) or external to the housing. If the temperature measured by the temperature sensor (15) rises above a certain predefined threshold temperature, the controller may be triggered by this event in the same way as it is triggered by a fire alarm from the wireless interface (12).

[00031] In an embodiment, related to the embodiment above, the current through the switch (13) is limited by a resistor (16) connected in series with the switch (13). The current may be limited to20, 30, 40, 50 or 100 mA. E.g. in a 230V IT-network a resistor of 4,3 kO will limit the current to about 30 mA, while in a 400V TN-network a resistor of 7,7 kQ is necessary to obtain the same current. 30 mA is a common rating of the RCDs in many regions. However, if RCDs with other ratings are used, the current and resistance may be varied accordingly.

[00032] In an embodiment, related to the embodiment above, the controller comprises a network type switch, arranged to be switched from a TN-network to an IT-network position, wherein the switch involves selecting the appropriate resistor.

[00033] The switch (13) is closed when the processor is triggered by an anomality, such as a wireless signal indicating an alarm and the processor is arranged for opening the switch after a limited time to prevent dangerous situations due to the imposed earth failure. In an embodiment that may be combined with any of the embodiments above, the processor (11) opens the switch (13) after 1 second. I.e., the connection or short circuit between the live wire and ground is limited to 1 second. In alternative embodiments the processor opens the switch after 10, 5, 4, 3, 2, 1, 0.5 or 0.1 seconds.

[00034] RCDs should be routinely tested by pressing the test button on the RCD. However, this is often forgotten, since RCDs are hidden and remotely located. In an embodiment that may be combined with any of the embodiments above, the processor (11) is therefore configured to repeatedly simulate the time-limited earth failure according to pre-defined time intervals. The purpose is automatic testing of the RCD. If the RCD works according to the requirements, the RCD will break the circuit, and the RCD has to be reset.

[00035] In the case where the RCD test is not successful, e.g. circuit is not broken, additional action is required. In an embodiment, related to the above, the controller (10) comprises an alarm output interface (18) and a voltage sensor (19) connected to the mains sub-circuit (100). The voltage sensor (19), as illustrated in Fig. 1, will measure the voltage over the mains (101, 102). If the voltage remains after the RCD test, the processor should trigger an alarm.

[00036] Thus, the processor (11) is configured to detect the voltage from the voltage sensor (19) after the time-limited earth failure has been simulated and to activate the alarm output interface (18) if the mains voltage is still above a pre-defined value.

[00037] In an embodiment, related to the embodiment above, the alarm output interface (18) is connected to an audible alarm unit (31). The audible alarm may be inside or outside the controller (10).

[00038] In an embodiment, related to any of the embodiments with the alarm interface above, the alarm output interface (18) is connected to a visible alarm unit (32). The visible alarm is, in an embodiment outside the controller (10).

[00039] In an embodiment, related to the method disclosed previously, the invention is also a corresponding method for fire detection and prevention for testing the RCD, comprising the steps of;

- repeatedly simulating the time-limited earth failure according to pre-defined time intervals,

- detecting the voltage from the voltage sensor (19) after the time-limited earth failure has been simulated and activating the alarm output interface (18) if the mains voltage is still above a pre-defined value.

[00040] Fig. 2 illustrates a typical installation of the fire detection and prevention system (1).

[00041] In an embodiment that may be combined with any of the embodiments above, the processor (11) is implemented in a microcontroller unit.

[00042] The power supply (14) , in an embodiment, that can be combined with any of the embodiments above, converts mains voltage to a DC voltage applicable for electronics digital circuits, e.g. 230 V AC to 3,3 or 5 VDC. Other output voltages may be used in addition, depending on the operating voltages of the different components in the system.

[00043] The switch (13) is, in an embodiment that can be combined with any of the embodiments above, a relay with a low voltage control signal that is controlled by the processor (11). Other switches such as high voltage transistors can also be used.

[00044] The wireless interface (12) comprises, in an embodiment that can be combined with any of the embodiments above, a radio frequency circuit (12) and an antenna (121). The wireless interface can be based on standard protocols and frequencies, such as e.g. Bluetooth.

[00045] The wired interface (17) comprises, in an embodiment that can be combined with any of the embodiments above, a serial interface. The serial interface may be an addressable interface to identify different fire detections sensors (31) on the same circuit.

[00046] The wireless and wired fire detection sensors (3, 31) can be any type of detector used for fire detection, such as; heat detectors, smoke detectors, e.g. ionization, light scattering and light obscuring or Carbon Monoxide detectors. It may also be a combination detector comprising more than one type of detector, such as e.g. combined heat and smoke detector. The wireless and wired fire detection sensor (3, 31) has a wireless interface compatible with the wireless interface (12) of the controller, and capable of transmitting a fire alarm signal on the wireless interface to trigger the controller (11). In an embodiment the sensor (3, 31) is battery operated.

[00047] In an embodiment that may be combined with any of the embodiments above, the controller (10) can be controlled over the wired or wireless interface. One or more of the following operating parameters may be retrieved or set;

- operating voltage,

- network type (TN/IT),

- time limited connection time,

- RCD test interval, day/date/time,

- mains voltage [00048] In a related embodiment the fire detection and prevention system (1) comprises an app for a smart phone or a computer arranged for controlling one or more of the setting above for the controller (10) directly over the wired or wireless interface.

[00049] In an embodiment that may be combined with any of the embodiments above, the controller (10) transmits alarms over the wired or wireless interface that may be detected by additional local devices such as wireless audible or visible indicators, e.g. speakers, buzzers, bells, lamps etc.

[00050] In an embodiment that may be combined with any of the embodiments above, the fire detection and prevention system (1) comprises a transponder comprising a first wireless interface arranged for communication with the controller (10), and a second interface such as a cell phone interface for forwarding alarms via the cell phone network to a specific cell phone or phones.

[00051] The second interface could also be used for communication with a remote server. The remote server may e.g. be part of an operation centre.

[00052] In a related embodiment the second interface may communicate directly with a wireless router and further over the Internet.

[00053] In the embodiments comprising a transponder, the operating parameters listed above may also be monitored and set remotely from e.g. an app connected to the Internet.

[00054] Different types of electric distribution networks exist, such as TN, IT and TT networks. The invention may be applied in the different types of networks, as long as the sub-circuit where the controller is installed is protected by an RCD. Adjustments may be made to accommodate the voltage level used, as explained above.

[0055] In the exemplary embodiments, various features and details are shown in

combination. The fact that several features are described with respect to a particular example should not be construed as implying that those features by necessity have to be included together in all embodiments of the invention. Conversely, features that are described with reference to different embodiments should not be construed as mutually exclusive. As those with skill in the art will readily understand, embodiments that incorporate any subset of features described herein and that are not expressly interdependent have been contemplated by the inventor and are part of the intended disclosure. However, explicit description of all such embodiments would not contribute to the understanding of the principles of the invention, and consequently some permutations of features have been omitted for the sake of simplicity or brevity.