Meter incorporating a fire detection device

Abstract

Electricity meter (1) comprising: - a cabinet (5) including a main part (7) and a secondary part (8) equipped with at least one first opening (11); - a smoke detection device positioned in the secondary part (8) of the cabinet and arranged to detect smoke particles originating outside the meter and having entered the secondary part through at least one first opening; - a processing unit positioned in the main part of the cabinet, connected to the smoke detection device, and arranged to detect a fire occurring outside the meter in the event of the presence of smoke particles in the secondary part of the cabinet. FIGURE IN ABRIDGED DIAGRAM: Fig. 1

Description

Title of the invention: Meter integrating a fire detection device

[0001] The invention relates to the field of electric meters.

[0002] BACKGROUND

[0003] It is possible, although extremely unlikely, that a faulty installation of an electric meter could cause a fire.

[0004] When the installer connects the incoming electrical cables to the meter's terminal block, they position the conductors in the power terminals and then tighten them mechanically. However, if one of the cables is not tightened properly, resistance builds up at that terminal. This resistance can cause overheating which, very rarely, can lead to a flame and a fire. Therefore, the fire is not caused by the meter itself, but rather by this faulty installation.

[0005] When a fire breaks out in the room housing the electricity meter, it is highly advantageous for the meter to be able to detect the fire and generate an alarm. This allows for rapid action to be taken to limit the consequences of the fire. It is also highly advantageous to be able to determine with certainty whether the electricity meter (or rather its installation) is the source of the fire, or whether the fire has another cause.

[0006] We seek to implement this dual detection function (fire and origin of the fire) in a meter, in a simple and inexpensive way so as not to increase the development and manufacturing costs of the meter.

[0007] OBJECT

[0008] The invention relates to:

[0009] - to detect the occurrence of a fire in a room in which there is a electricity meter;

[0010] - to determine whether or not the meter is the cause of the fire;

[0011] - and this in a simple and inexpensive way.

[0012] SUMMARY

[0013] To achieve this goal, an electricity meter is proposed comprising:

[0014] - a box including a main part and a secondary part equipped with minus an initial opening;

[0015] - a smoke detection device positioned in the secondary part of the cabinet and arranged to detect smoke particles coming from outside the meter and having entered the secondary part via at least one first opening;

[0016] - a processing unit positioned in the main part of the enclosure, connected to the smoke detection device, and arranged to detect a fire occurring outside the meter in the event of the presence of smoke particles in the secondary part of the box.

[0017] Thanks to the smoke detection device, the meter can therefore not only detect a fire, but also provide formal proof that it is not itself (or its installation) the cause of the fire.

[0018] The smoke detection device is very simple and very inexpensive to implement.

[0019] An electric meter as previously described is also proposed, the secondary part of the box being located in a lower portion of the meter.

[0020] An electric meter as previously described is also proposed, comprising a partition separating the main and secondary parts of the box, with at least one first opening positioned at the level of a lower portion of the secondary part of the box, the box further comprising at least one second opening formed in the partition.

[0021] An electric meter as previously described is also proposed, in which the processing unit and the smoke detection device are mounted on the same printed circuit board which extends into the main and secondary parts of the box.

[0022] An electricity meter as previously described is further proposed, in which the smoke detection device comprises a light emitter arranged to emit light signals and a light receiver, which are positioned in the secondary part of the enclosure such that:

[0023] - when the secondary part does not contain smoke particles, the receiver of light does not detect the light signals emitted by the light emitter;

[0024] - when the secondary part contains smoke particles, the light signals emitted by the light emitter are at least partially reflected by said smoke particles and detected by the light receiver.

[0025] An electric meter as previously described is further proposed, in which a temperature sensor is also integrated, the processing unit being arranged to evaluate an ambient temperature prevailing outside the meter from temperature measurements produced by the temperature sensor, the processing unit being arranged to detect a fire occurring outside the meter:

[0026] - in case of the presence of smoke particles in the secondary part of the box;

[0027] - and / or if the ambient temperature is above a predefined threshold.

[0028] An electricity meter as previously described is also proposed, the processing unit being arranged to evaluate the ambient temperature from measurements of temperature and measurements of a current supplied to an installation whose electrical energy consumption is measured by the electricity meter.

[0029] A method for detecting a fire and its origin is also proposed, implemented in the meter processing unit as previously described, and comprising the step of detecting a fire occurring outside the meter in the event of the presence of smoke particles in the secondary part of the box.

[0030] A method as previously described is further proposed, implemented in the processing unit of the meter as previously described, and further comprising the steps of:

[0031] - evaluate the ambient temperature outside the meter;

[0032] - detect a fire occurring outside the meter in the event of the presence of smoke particles in the secondary part of the cabinet, and / or if the ambient temperature is above a predefined threshold.

[0033] A computer program is also proposed comprising instructions which lead the processing unit of the meter as previously described to execute the steps of the process of detecting a fire and the origin of the fire as previously described.

[0034] A computer-readable recording medium is also proposed, on which the computer program as previously described is recorded.

[0035] The invention will be better understood in the light of the following description of a particular, non-limiting embodiment of the invention. Brief description of the drawings

[0036] Reference will be made to the attached drawings, among which:

[0037] [Fig-1] [Fig. 1] represents a perspective view of the electric meter and its cover;

[0038] [Fig.2] [Fig.2] represents a simplified cross-sectional view of the electric meter, along a plane parallel to the front face of the meter;

[0039] [Fig.3] [Fig.3] represents a simplified diagram of the meter. DETAILED DESCRIPTION

[0040] With reference to Figures 1 to 3, the electricity meter 1 is intended to measure the electrical energy consumption of an installation 3 and to transmit the measurements to the Information System (IS) of the electricity supplier. This electrical energy is supplied to the installation 3 by a distribution network 4. The meter 1 is shown here as a single-phase meter, but it could be a polyphase meter.

[0041] The meter 1 is installed in a room by being positioned against a wall of said room and fixed to the wall.

[0042] The meter 1 comprises a housing 5 and a removable cover 6 (made of plastic, for example). The housing 5 includes a rear face, which is also the rear face of the meter 1, and is intended to be applied to and fixed to the wall. The cover 6 includes a face, which is also the front face of the meter 1, and is visible and accessible by the subscriber or an operator.

[0043] Here, all position terms (front, rear, upper, lower, top, bottom, etc.) must be interpreted considering that the meter 1 is installed in its nominal operating position (its rear face fixed to a vertical surface).

[0044] The box 5 is a single unit. It comprises a main part 7, defining a main volume inside the box 5, a secondary part 8, defining a secondary volume inside the box 5, and a terminal block 9.

[0045] The secondary part 8 and the terminal block 9 are located below the main part 7, i.e. the main part 7 is located in an upper portion of the meter 1 and the secondary part 8 and the terminal block 9 are located in a lower portion of the meter 1.

[0046] Here, the secondary part 8 and the terminal block 9 are located next to each other, at approximately the same height.

[0047] The main part 7 contains most of the electrical and electronic components of the meter 1.

[0048] The terminal block 9 is accessible by removing the cover 6 (as well as another cover, not shown, locked and sealed), and includes power terminals 10 to which are connected the electrical supply cables (connected to the network 4) and the cables connected to the installation 3.

[0049] The secondary part 8 has a parallelepiped shape and includes at least one opening, and advantageously at least a first opening 11 (in this case several) and at least a second opening 12 (in this case several).

[0050] The first openings 11 are positioned at the level of a lower portion of the secondary part 8 of the box 5. Here, the first openings 11 are formed in a lower face of the box 5. The second openings 12 are formed in a partition 14 (here a horizontal partition) separating the main part 7 and the secondary part 8 of the box 5.

[0051] The first openings 11 form an air inlet, through which air can enter the secondary part 8 of the box 5.

[0052] The second openings 12 form an air outlet, through which air can exit from the secondary part 8 of the box.

[0053] The first openings 11 and the second openings 12 give the secondary part 8 of the box 5 a "cage" shape.

[0054] The air inlet and outlet create air circulation. Thus, when smoke Smoke is present in the room outside meter 1, in the vicinity of meter 1. This smoke enters the secondary section 8 via the air intake and is trapped there. This cage incorporates a smoke detection device 15.

[0055] The partition 14 therefore prevents smoke from entering massively into the main part 7 of the box 5, but still allows it from below, in a limited way.

[0056] This partition 14 is important because the main part 7 of the meter 1 must be protected from fumes and various impurities. The protection must meet the requirements of protection rating IP51 if the meter 1 is intended for indoor installation, and IP54 if the meter 1 is intended for outdoor installation. However, the area near the terminal block 9 at the bottom of the meter 1, where the secondary part 8 is also located, only needs to be IP2x, which is much less restrictive and allows for the presence of significant amounts of smoke in particular.

[0057] We are now interested in the electrical and electronic components of the meter.

[0058] The meter 1 includes sensors (not shown) for measuring the electrical energy consumed by the installation 3. These sensors measure in particular the current flowing through the meter 1 (supplied by the network 4 to the installation 3) and the voltage applied by the network 4 at the input of the installation 3 (and of the meter 1).

[0059] The meter 1 also includes a switching device 17 which is intended to selectively cut off the current supplied to the installation 3. The switching device 17 includes a switch for each phase of the distribution network 4 (here a single switch).

[0060] The counter 1 further comprises a processing unit 18 (electronic and software). The processing unit 18 includes at least one processing component 19, which is, for example, a general-purpose processor, a digital signal processor (DSP), a microcontroller, or a programmable logic circuit such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC). The processing unit 18 also includes one or more memories 20, connected to or integrated into the processing component. At least one of these memories 20 forms a computer-readable storage medium on which is stored at least one computer program comprising instructions that lead the processing unit 18 to execute the steps of the process for detecting a fire and its origin, which will be described below.

[0061] Here, the processing unit 18 comprises a "metrology" microcontroller 19a which, in particular, acquires the measurements taken by the sensors of the counter 1 and performs certain processing on said measurements, and an "application" microcontroller 19b which, in particular, controls the switching element 17. It is also in the microcontroller ap Application 19b states that the process for detecting a fire and its origin is implemented.

[0062] The smoke detection device 15 makes it possible to detect the presence or absence of smoke outside the meter 1.

[0063] The smoke detection device 15 includes a light emitter, in this case a light-emitting diode 21 (LED), and a light receiver, in this case a photodiode 22. The LED 21 generates infrared light (for example with a wavelength of 860 nm), which the photodiode 22 can detect when the light rays reach its sensitive cell.

[0064] The LED 21 emits light signals 23. The LED 21 and the photodiode 22 are positioned in the secondary part 8 of the enclosure 5 such that:

[0065] - when the secondary part 8 does not contain smoke particles, the photodiode 22 does not detect the light signals 23 emitted by the LED 21;

[0066] - when the secondary part 8 contains smoke particles, the signals luminous 23 emitted by LED 21 are at least partially reflected by said smoke particles and detected by photodiode 22.

[0067] Here, the LED 21 and the photodiode 22 are positioned in the secondary part 8 of the enclosure 5 such that the LED 21 emits light signals 23 along a first axis XI, and the photodiode 22 optimally detects light signals arriving at its sensitive cell along a second axis X2 which is perpendicular to the first axis XL. Thus, in the absence of smoke particles in the secondary part 8, the photodiode 22 does not detect the light signals emitted by the LED 21. On the other hand, in the presence of smoke particles, some of the light signals emitted by the LED 21 are reflected by the smoke particles and reach the photodiode 22.

[0068] The photodiode 22 produces a binary electrical signal at its output.

[0069] In the absence of smoke, this binary signal takes a first value.

[0070] When the quantity of smoke particles present in the secondary part 8 exceeds a certain threshold, the binary electrical signal takes a second value.

[0071] The application microcontroller 19b includes a PI port connected to the LED 21 and a P2 port connected to the photodiode 22. The microcontroller 19b regularly produces a voltage which it applies to the terminals of the LED 21 via the PI port so that the latter emits light signals, and acquires via the P2 port the binary electrical signal produced by the photodiode 22 to detect the absence or presence of smoke in the secondary part 8 of the box 5, and therefore in the room.

[0072] The application microcontroller 19b therefore detects a fire occurring outside the meter 1 in the event of the presence of smoke particles in the secondary part 8 of the box 5.

[0073] Here, the electronic components of the processing unit 18, the switching element 17 and the components of the smoke detection device 15 are mounted on the same printed circuit board 24 positioned in the enclosure 5 parallel to its front face.

[0074] The printed circuit board 24 therefore comprises a main portion 25, on which are mounted, in particular, the metrology microcontroller 19a, the application microcontroller 19b, and the switching element 17, and a secondary portion 26, on which are mounted, in particular, the LED 21 and the photodiode 22.

[0075] The printed circuit board is in one piece and here has an "L-shaped" form: the main portion 25 of the printed circuit board 24 has the shape of a rectangle, and the secondary portion 26 of the printed circuit board 24 also has the shape of a rectangle of reduced dimensions having one side which extends in the continuation of one side of the main portion.

[0076] The main portion 25 of the printed circuit 24 is positioned in the main part 7 of the box 5 and the secondary portion 26 of the printed circuit 24 is positioned in the secondary part 8 of the box 5.

[0077] The printed circuit board 24 passes through the partition 14 via an opening 27 (visible in [Fig. 1]) provided for this purpose. The printed circuit board 24 is in direct contact with the partition 14 at the level of this opening.

[0078] Advantageously, the counter 1 also uses temperature information provided by a temperature sensor integrated into the counter.

[0079] The temperature sensor is in this case a thermistor 30 of type NTC (for Negative Temperature Coefficient).

[0080] The thermistor 30 is mounted on the printed circuit board 24 and is located at a non-hot point in the enclosure 5. It is therefore away from the switching member 17. Here, the thermistor 30 is located near a first corner of the main portion 25 of the printed circuit board 24 and the switching member 17 is located near a second corner of the main portion 25 of the printed circuit board 24, the first corner and the second corner being diagonally opposite.

[0081] This thermistor 30 can be used to evaluate the ambient temperature prevailing in the room outside the meter 1.

[0082] The temperature measured by the thermistor 30 is not directly the ambient temperature, but an image of the latter.

[0083] The difference between the temperature measured by the thermistor 30 and the ambient temperature is a function of the current I flowing through the meter 1 (and consumed by the installation 3), and therefore via the switching element 17. The current / causes internal heating in the meter 1 which by diffusion will act on the temperature measured by the thermistor 30 regardless of the ambient temperature.

[0084] The processing unit 18 is therefore arranged to evaluate the ambient temperature from temperature measurements produced by the thermistor 30 and measurements of the current supplied to the installation 3, whose electrical energy consumption is measured via the electricity meter 1.

[0085] The temperature & measured by the thermistor 30 is therefore a function of the ambient temperature Tamb (ambient around the meter 1 in its external environment in the room where it is located) and the value of the current / (which can typically range from 0 to 100 A, and which can be equal to 200 A in the USA):

[0086] & = Tamb + AT + K*I2

[0087] AT being determined by design and typically equal to 10 °C, and K being a factor also determined by design and typically such that:

[0088] K = 0.025 °C / A2

[0089] For example, if there is a current of 60 A flowing through meter 1, the difference between & and Tamb will be:

[0090] (io + 0.025*602) = 19°C-

[0091] The application microcontroller 19b therefore measures the resistance of the thermistor 30, deduces the temperature Δ, and then deduces the ambient temperature Tamb from the temperature 0. The application microcontroller 19b can therefore estimate the ambient temperature Tamb in real time.

[0092] The application microcontroller 19b then detects a fire occurring outside the counter 1:

[0093] - in case of the presence of smoke particles in the secondary part 8 of the box 5;

[0094] - and / or if the ambient temperature is above a predefined threshold.

[0095] The predefined threshold is for example equal to 60°C.

[0096] The application microcontroller 19b triggers a first alarm in the event of the presence of smoke particles. The application microcontroller 19b triggers a second alarm in the event of an abnormally high temperature.

[0097] If one or both of these alarms are triggered, meter 1 detects a fire. Meter 1 then sends an alarm message corresponding to the HES (Head End System) of the electricity supplier's information system. The alarm message can be a first alarm message indicating "abnormally high ambient temperature," or a second alarm message indicating "presence of smoke." Both alarm messages can be sent simultaneously.

[0098] As we have seen, a fire will generally trigger at least one of the two alarms, or even both. Counter 1 will therefore signal, via the alarm message(s), that it detects a probable fire in its environment before it is itself destroyed.

[0099] The sending and receiving of this or these alarm messages constitutes formal proof that meter 1 itself is not the cause of the fire, and allows us to exonerate meter 1. Indeed, if the fire originated from the Meter 1 (or rather, its presumably faulty installation) will not immediately detect an abnormally high ambient temperature or smoke because it is burning from the inside out. Therefore, it will not have time to send an alarm message to the Fire Safety System's HES (Head and Safety Equipment) because it will be destroyed beforehand. The fact that the HES received at least one of the two alarm messages allows it to rule out meter 1 as the cause of the fire.

[0100] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0101] The shape of the meter box and, in particular, of its main part and its secondary part, could be different from that described here.

[0102] This is also the case for the printed circuit board. The components of the smoke detection device could be mounted on a printed circuit board separate from that of the main part of the enclosure.

[0103] The smoke detection device could be different. The wavelength of the emitted light signals could be different. The components used could be different (for example, a phototransistor instead of a photodiode). More generally, any type of technology can be used (for example, a linear optical detector).

Claims

Demands

1. Electric meter (1) comprising: - a cabinet (5) including a main part (7) and a secondary part (8) having at least one first opening (11); - a smoke detection device (15) positioned in the secondary part (8) of the cabinet and arranged to detect smoke particles coming from outside the meter and having entered the secondary part through at least one first opening; - a processing unit (18) positioned in the main part of the cabinet, connected to the smoke detection device, and arranged to detect a fire occurring outside the meter in the event of the presence of smoke particles in the secondary part of the cabinet.

2. Electric meter according to claim 1, the secondary part (8) of the box being located in a lower portion of the meter.

3. Electric meter according to any one of the preceding claims, comprising a partition (14) separating the main part (7) and the secondary part (8) of the cabinet (5), the at least one first opening (11) being positioned at the level of a lower portion of the secondary part of the cabinet, the cabinet further comprising at least one second opening (12) formed in the partition (14).

4. Electric meter according to any one of the preceding claims, wherein the processing unit and the smoke detection device are mounted on the same printed circuit board (24) which extends into the main part (7) and the secondary part (8) of the box (5).

5. Electric meter according to any one of the preceding claims, wherein the smoke detection device (15) comprises a light emitter (21) arranged to emit light signals (23) and a light receiver (22), which are positioned in the secondary part (8) of the box (5) such that: - when the secondary part does not contain smoke particles, the light receiver does not detect the light signals emitted by the light emitter; - when the secondary part contains smoke particles, the light signals emitted by the light emitter are at least partially reflected by said smoke particles and detected by the light receiver.

6. Electricity meter according to one of the preceding claims, in which also includes a temperature sensor (30), the processing unit (18) being arranged to evaluate an ambient temperature outside the meter from temperature measurements produced by the temperature sensor, the processing unit being arranged to detect a fire occurring outside the meter: - in the event of the presence of smoke particles in the secondary part of the box; - and / or if the ambient temperature is above a predefined threshold.

7. Electric meter according to claim 6, the processing unit (18) being arranged to evaluate the ambient temperature from temperature measurements and measurements of a current supplied to an installation (3) whose electrical energy consumption is measured by the electric meter.

8. Method for detecting a fire and the origin of the fire, implemented in the processing unit (18) of the meter according to any one of claims 1 to 5, and comprising the step of detecting a fire occurring outside the meter in the event of the presence of smoke particles in the secondary part (8) of the box (5).

9. A method according to claim 8, implemented in the meter processing unit according to any one of claims 6 or 7, and further comprising the steps of: - evaluating the ambient temperature outside the meter (1); - detecting a fire occurring outside the meter in the event of the presence of smoke particles in the secondary part of the cabinet, and / or if the ambient temperature is above a predefined threshold.

10. Computer program comprising instructions that cause the processing unit (18) of the meter according to any one of claims 1 to 5 to perform the steps of the method for detecting a fire and the origin of the fire according to claim 8.

11. Computer-readable recording medium on which the computer program according to claim 10 is recorded.

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