FIELD OF THE INVENTION

The present invention relates to a system for turning off the power supply in a predetermined part of an electrical system . In particular the present invention relates to a system where an apparatus for detecting a fire or a ignitable gas/substance/material is arranged to control a power controlling apparatus to turn of the electrical power when a fire or an ignitable gas/material is detected.

BACKGROUND OF THE INVENTION While most smoke detector systems solely are designed to sound an alarm when smoke is detected and a fire has already broken out, the present invention relates to a system which can prevent certain fires such as electrical or gas fires, from breaking out in the first place.

Typically in an electrical fire where a household appliance is the cause, smoke will occur prior to the fires actually breaking out. By cutting the supply of power to the appliance causing the smoke to develop, the fire will be prevented from breaking out.

In a situation where the fire is caused by a gas leak, a fire may be caused by a single spark e.g. when turning on an electrical appliance such as a lamp. By cutting off the power upon detection of a gas, such fires can equally be prevented from breaking out. Systems that are capable of cutting off the power upon detection of gas or fire are known. Examples of such systems are e.g. disclosed in the German utility model DE 203 02 697 Ul, British patent application GB 2 438 252 A and Danish patent DK 173739 Bl. These documents disclosed systems that are able to detect smoke, fire or gas and cut off the power in case of such a detection of smoke, fire or gas. The systems may be adapted to issue an alarm signal and notify a third part such as the fire or police department.

However, dangerous situations may arise when power is suddenly cut off in a location without the people present in the location are aware that the power is cut off.

DESCRIPTION OF THE INVENTION In a first aspect, the present invention relates to a system for turning off a power supply in a predetermined part of an electrical system, the system comprising : - a detector for determining a fire and/or the presence of an ignitable gas and/or the presence of an air-born ignitable material; and

- a power-controlling apparatus arranged to turn off an electrical power supply in the predetermined part of the electrical system; wherein the detector is adapted to control the power-controlling apparatus such that upon detection of a fire and/or an ignitable material, the power-controlling apparatus is activated to turning off the power in the predetermined part of the electrical system and the detector is adapted to emit the signal after a predetermined period of time, for warning a user that the power-controlling apparatus is about to turn off the electricity. The detector may warn the user by emitting an alarm signal shortly before the power is turned off.

The predetermined part may be a predetermined area of a building, such as a

predetermined room of the building. In one embodiment, the predetermined area is an entire building. The electrical system may be an electrical system which is adapted to supply an altering current or a direct current.

When the system for turning off the power supply, turns off the power, no power is supplied to the predetermined part of the electrical system . In one example, an entire electrical system is shut down when the system for turning off the power operates the power controlling apparatus to turn off the power.

However, the present invention provides for the option that persons present in the area where the predetermined part of the electrical system is operating are warned about the cut off of power before it actually appears, whereby dangerous situations, e.g.

dangerous situations due to panic can be avoided. The warning signal may e.g. be a light and/or sound signal emitted by the detector a predetermined time before the detector sends a signal to the power controlling apparatus to cut off the power.

In the context of the present invention, the term "fire" shall be understood as a rapid oxidation of a material in a chemical process of combustion. The chemical process may release one or more of heat, light, and various reaction products such as incandescent solid particles e.g. soot.

In the context of the present invention, the term "ignitable gas" shall be understood as a gas which is ignitable at its current temperature and at any other temperature, such as at a temperature in the range 20-30 degrees Celsius, such a temperature in the range 30-100 degrees Celsius, such as a temperature above 100 degrees Celsius, such as temperature above 200 degrees Celsius, such as temperature above 500 degrees Celsius, such as a temperature above 1000 degrees Celsius, such as a temperature above 1500 degrees Celsius, such as a temperature above 2000 degrees Celsius. In one embodiment, the ignitable gas is a gas which at ambient temperature and pressure forms a flammable mixture with air at a predetermined concentration, such as a concentration of 50 percent (%vol or %mas) or less, such as a concentration of 40 percent or less, such as a concentration of 30 percent or less, such as a concentration of 20 percent less, such as a concentration of 10 percent or less. Examples of ignitable gasses are hydrocarbons such as gasoline, ethane, propane, butane, and pentane.

In the context of the present invention the term "ignitable air-born material" shall be understood a material which when air born in a predetermined concentration, is flammable at a predetermined temperature and pressure. The above temperature ranges also applies to the ignitable air-born materials. An example of such a material is dust suspended in air e.g. saw dust.

In one embodiment, the detector is adapted to control the power-controlling apparatus such that upon detection of a fire and/or an ignitable material, the power-controlling apparatus is activated to turning off the power in the predetermined part of the electrical system.

In one embodiment, the detector comprises a controller which is electrically connected to a sensor for determining a fire and/or the presence of an ignitable gas and/or the presence of an air-born ignitable material. Upon determination of the ignitable gas or the presence of an ignitable gas or material, the sensor sends a signal to the controller. Subsequently, the controller may be adapted to send a signal to the power-controlling apparatus.

In one embodiment, the controller is adapted to send the signal to the power-controlling apparatus only if one or more predetermined conditions are met. In another

embodiment, the controller is adapted to emit the signal after a predetermined period of time, such as after 5 seconds, such as after 10 seconds, such as after 15 seconds, such as after 20 seconds, such as after 30 seconds. During these periods, the detector may be adapted to emit an acoustic signal or a light signal, for warning a user that power- controlling apparatus is about to turn off the electricity. In one embodiment, the detector for determining a fire is adapted to determine at least one of:

- an increase of the temperature in a predetermined location;

- the presence of smoke in the predetermined location; and - the presence of a predetermined gas in the predetermined location.

Accordingly, the detector may in one embodiment comprise a temperature sensor which is controlled such that when the temperature is above a predetermined threshold in the predetermined location, a signal is send to the power controlling apparatus and/or the control unit of the controller of the detector. Examples of temperature sensors are temperature gauges, thermistors, and thermocouples.

Moreover, the detector may comprise a smoke detector which is controlled such that when smoke is detected, a signal is send to the power controlling apparatus and/or the control unit of the controller of the detector. The smoke detectors may comprise an photoelectric sensor for determining the smoke and/or a ionization sensor for determining the smoke.

Furthermore, the detector may comprise a sensor for determining the presence of an ignitable/flammable gas, and may upon detection of such a gas be adapted to send a signal to the power controlling apparatus and/or the control unit of the controller of the detector. The detector for determining the presence of an ignitable/flammable gas may be adapted to detect a combustible gas and/or a flammable gas. Examples of gas sensors are catalytic bead sensors, explosimeters, infrared point sensors and infrared open path detectors.

In one embodiment, the power-controlling apparatus comprises at least one of:

- a relay; - a residual-current device; and

- a solid-state relay.

It will be appreciated that most buildings may comprise a power meter (also known as an electricity meter), which is adapted to monitor the use of power in the building. This meter is often used for billing purposes. In a first embodiment, the power-controlling apparatus may be arranged such that it can cut off any power feed into such as power meter, whereby the power supply to the entire building is cut off. Alternatively in a second embodiment, the power-controlling apparatus may be arranged such that it can cut off any power feed out of the power meter, whereby the power meter is supplied with power, while the power supply to the rest of the electrical network in the building is cut off. In the first embodiment, the order of elements is as follows: external power supply - power controlling apparatus - power meter - electrical system in the building. Contrary hereto the order in the second embodiment, is as follows: external power supply - power meter - power controlling apparatus - electrical system in the building. The abovementioned external power supply may be a public power supply and/or a private power supply.

In order to allow a user to turn on the power again, the detector may comprise a user- operatable switch which when activated causes the power-controlling apparatus to turn on the power. The switch may be provided on an outer surface of the detector.

Alternatively, or as a supplement, the switch may be controllable by means of a remote controlling device.

In one embodiment, the power-controlling apparatus is adapted to turn off the power by providing a 'leakage current' over the incoming and the outcomming terminals of the residual-current device. The result is that the residual-current device turns off the power. Accordingly, the power-controlling apparatus may be adapted to be attached to and electrically connected with the residual-current device. In the alternative, the power-controlling device may form an integral part of the residual-current device. In yet another embodiment, the power-controlling apparatus may be adapted to be inserted into a plug (e.g. a mains plug). In the latter example, the power-controlling apparatus may be inserted into the mains plug in the same room as the detector.

In one embodiment, the detector and the power-controlling apparatus each comprises a communication unit. Moreover, the detector and the power-controlling apparatus may be adapted to communicate with each other by means of said communication units. In one embodiment, the communication unit is adapted to communicate wirelessly.

Alternatively, or as a supplement, the communication unit is adapted to communicate via a wired connection e.g. by utilizing a power line, such as mains (e.g. a 220 volts line)

When a hazardous situation is detected, it may be advantageous to warn a user. Thus in one embodiment, the detector may comprise an apparatus for emitting light and/or an acoustic signal. In one embodiment, the detector may comprise a communication unit which is adapted to communicate with an external device, such as a mobile telephone or a computer connected to a network (e.g. the internet). In one embodiment, the system comprises a first and a second location, - the first location comprising :

- a first detector for determining a fire and/or the presence of an ignitable gas and/or the presence of an air-born ignitable material in the first location, - a first electrical system which is arranged to provide electrical power in the first location, and

- a first power-controlling apparatus arranged to turn off an electrical power supply in the first electrical system upon receipt of a signal from the first detector; and - the second location comprising

- a second detector for determining a fire and/or the presence of an ignitable gas and/or the presence of an air-born ignitable material in the second location,

- a second electrical system which is arranged to provide electrical power in the second location, and

- a second power-controlling apparatus arranged to turn off an electrical power supply in the second electrical system upon receipt of a signal from the second detector; and wherein the electrical power supply at the second electrical system remains unchanged when the first power controlling apparatus turns off the power in the first electrical system, and/or wherein the electrical power supply at the first electrical system remains unchanged when the second power controlling apparatus turns off the power in the second electrical system. The first location may be a first room in a building, while the second location may be a second room. In one embodiment, the first location is one floor/storey of a building, while the second location is a second floor/storey.

It may be appreciated, that the system according to the present invention may be adapted to be used in connection with more than two locations, such as in connection with three locations, such as four locations, such as five locations, such as six locations, such as seven locations, such as eight locations, such as nine locations etc.

In one embodiment, a detector is provided in each of the locations. In another embodiment, a detector is provided in less than all of the locations, such as in 75 percent of the locations, such as in 50 percent of the locations, such as in 25 percent of the locations. Additionally, an electrical system may be provided in each of the locations.

When a fire occurs, it may be advantageous that all the detectors in the building warn persons who are in the building. In one embodiment, the first and the second detectors for determining a fire and/or the presence of an ignitable gas and/or the presence of an air-born ignitable material are adapted to communicate with each other such that upon detection of a fire and/or the presence of an ignitable gas and/or the presence of an air- born ignitable material by one of the first and the second detectors, both of the first and the second detectors emits an visual and/or an acoustic alarm.

In a second aspect, the present invention relates to a method of controlling a system for turning off a power supply in a predetermined part of an electrical system, the system comprising

- a detector for determining a fire and/or the presence of an ignitable gas and/or the presence of an air-born ignitable material; and

- a power-controlling apparatus arranged to turn off an electrical power supply in the predetermined part of the electrical system; wherein the detector is adapted to control the power-controlling apparatus, the method comprising the steps of:

- determining the presence of a fire or an ignitable gas or air-born material by means of the detector; - emitting a signal from the detector after a predetermined period of time for

warning a user that the power-controlling apparatus is about to turn off the electricity;

- emitting a signal from the detector to the power-controlling apparatus; - operating the power-controlling apparatus to turn off the power in the

predetermined electrical system, upon receipt by the power-controlling apparatus of the signal emitted by the detector.

It will be appreciated that the invention according to the second aspect may comprise any combinations of features and/or elements of the invention according to the first aspect.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be described with reference to the figures in which:

Fig. 1 discloses an example of a system according to the present invention installed in a plurality of rooms, and

Fig. 2 discloses an example of a system according to the present invention installed in one room which included one electrical apparatus in the form of a television.

DETAILED DESCRIPTION OF THE FIGURES

Fig. 1 discloses a system 100 for turning off the power supply in a predetermined part of an electrical system . The system 100 is installed in a building 101 with four rooms

A,B,C,D. Provided in each of the rooms A,B,C,D is one detector 102a,102b,102c,102d for determining a fire and/or the presence of an ignitable gas and/or the presence of an air- born ignitable material. Moreover, each of the rooms A,B,C,D also comprises a power controlling apparatus 104a, 104b, 104c,104d, which is arranged to turn off the electrical power supply in the respective room A,B,C,D. Thus if one of the detectors

102a, 102b, 102c,102d detects a fire or an ignitable gas/material, the detector

102a, 102b, 102c, 102d is adapted to operate the power-controlling apparatus

104a, 104b, 104c,104d provided in the same room A,B,C,D, such that the power supply to all electrical apparatuses in said room A,B,C,D is terminated. The effect is that fire or explosion may be prevented. Typically the detector 102a, 102b, 102c,102d may be provided in the sealing, however, as some explosive gasses may be heavier than air, it may be advantageous to provide the detector 102a,102b _/ 102c,102d near the floor. In one embodiment, each detector 102a, 102b, 102c,102d comprises two sensors - one provided near the floor and one provided near the ceiling. In one embodiment, each of the detectors 102a, 102b, 102c,102d are adapted to turn off the power supply in the same room A,B,C,D as it is provided and in one or more neighboring rooms A,B,C,D.

Alternatively, or as a supplement, a power-controlling apparatus 104e may be provided centrally in the electrical system. In the example of Fig. 1 the power-controlling apparatus 104e is arranged to turn off power at a point prior to the power meter 106, whereby activation of the power-controlling apparatus 104e causes electrical power supply to be terminated such that neither the power meter nor any of the rooms A,B,C,D are supplied with power. The power-controlling apparatus 104e may be integrated into the power-meter.

Fig. 2 discloses room A of Fig. 1 in further detail. In the room is provided a detector 102a for determining the presence of a fire and/or an ignitable gas and/or the presence of an air-born ignitable material. Moreover, a power-controlling apparatus 104a is provided, which is adapted to be controlled by the detector 102a. If a fire develops in the television set 108, any smoke developed is detected by the detector 102a, which instantly turns off the power supply to the television set 108 by means of the power- controlling apparatus 104a.