FR2790130A1 - Fire detection/protection mechanism having electrical connection branches with detectors siren alarms and each branch end having test signal element output. - Google Patents

Abstract

The detection mechanism has a central unit (1) monitoring detector and siren alarm elements in different circuit branches (11,12,13). Each branch has a branch end (3) unit which provides a test signal.

Description

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  DETECTION DEVICE AND METHOD

OF IMPLEMENTATION

  The present invention relates generally to protective devices and more particularly to protective devices intended to detect

  fires, extinguish and control them.

  These protection devices comprise, in a manner known per se, a detection network comprising detectors, manual triggers, etc. distributed in the zone to be monitored, one or more alarm, extinction or control devices, and an electronic central unit capable of monitoring the detection network and of issuing an alarm when a start of fire is detected, of implementing extinguishing means

and / or control.

  All the elements of the device, detectors, sirens, etc., must be connected to the central so as to allow an exchange of information between said central and said elements both from the central to the elements in order to control them, and from elements to the central so that the latter is informed of the state of

every element.

  Usually, the wired networks connecting the elements of a protection device are produced according to two modes, the conventional mode and the

addressed mode.

  In the conventional mode, generally reserved for small to medium-sized installations, all the elements of the device are connected in series and the line thus formed is connected to the central unit at one end and to a branch end circuit at the other end. The end of branch circuit is intended to establish, continuously or not, a reference signal which the control unit detects in order to know the state of the line of the

monitoring device.

  This wiring mode allows the implementation of an economical device with regard to the electronic means which must be implemented between the central

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  and the different elements but quite expensive with regard to the cost of the connection. The additional cost due to wiring is further accentuated when it is necessary to connect sirens because these often require the use of rather expensive special cables. The disadvantage of this type of cabling is that it forces a link to be established between the consumption of the standby elements and the consumption in the end circuit.

  branch to allow detection of all possible circuit breaks.

  In the addressed mode, generally implemented in medium to large installations, the elements are wired either in series or on branches and

  an address is assigned to each item.

  This wiring method requires the use of expensive electronic means to allow communication between each element and the central unit, by

  however, it saves on the cost of wiring.

  The present invention aims to propose a device whose wiring is such that it allows savings to be made both on the electronic means to be put

and on the wiring.

  To this end, the invention relates to a detection device comprising a central unit and elements, for example detectors or sirens, connected to the central unit by an electrical connection comprising at least one branch carrying at least one element, characterized in that each branch has an end-of-branch circuit,

  each end-of-branch circuit corresponding to a witness signal.

  The device according to the invention is also remarkable in that each branch is connected, directly or through other branches, to a section connected to the central unit. The invention also provides a method of implementing the device according to the invention, characterized in that a reference current is defined, linked to the standby consumption of all the elements of the link and to the consumption of all end-of-branch circuits, equal to the standby current flowing in the electrical connection. This process is also remarkable in that: - the reference current is automatically determined by the control unit during each commissioning,

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  - the reference signal is determined by an operator during each commissioning or during each maintenance operation, - when the device comprises elements whose consumption is subject to cyclic variations, the value of the reference current of the link is equal to the average value of the standby current measured during a significant reference period, longer than the period of cyclic variations, - when a short circuit occurs in the electrical link, the control unit detects an increase in the circulating current in the electrical connection and implements a limitation or disconnection circuit, - when a cut occurs in the electrical connection, the control unit measures a reduction in the reference current at least equal to that fixed by one of the circuits end of branch, - the reference current is fixed by the end of branch circuits permanently, - the reference current is fixed p ar the branch end circuits intermittently, - the reference current is set cyclically by the branch end circuits, - the reference current is fixed by the end of branch circuits at the request of the central unit, - the consumption of the different end-of-branch circuits present in the link are planned different from each other so as to allow

  identification of the damaged branch when a break is detected.

  The invention will be better understood thanks to the description which follows given

  by way of nonlimiting example with reference to the accompanying drawings in which: - Figure 1 shows a first embodiment of the device according to the invention, - Figure 2 shows an embodiment of the wiring of a building with four levels , - Figures 3a to 3c show three alternative embodiments of a device according to the invention,

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  - Figure 4 shows an alternative embodiment of a circuit according to the invention. As shown in FIG. 1, the wiring of a detection device constitutes an electrical connection composed of different branches 11, 12, 13 each comprising an element 2, such as a detector or a siren, or several elements 2 in series. According to the invention, each branch comprises an end of branch circuit 3 and each end of branch circuit 3 corresponds to a control signal, and is connected,

  directly or through other branches, to a section 10 connected to the central unit.

  The control signal corresponding to each end-of-branch circuit may be of different types, it may be a coded signal, or of a determined frequency, the presence of which must be determined on the electrical connection, or a current consumption due to a resistive mounting. The topology used for the device according to the invention falls under the two known cabling modes, it is simpler to carry out than in the conventional mode since the elements are, according to the geography of the places, connected to the central unit in series with other elements or by separate branches, and it requires less complex electronic management means than the addressed mode since

  does not assign addresses to items.

  FIG. 2 shows the wiring produced for a device according to the invention intended for the protection of a building with four levels. In this exemplary embodiment, the elements 2 are connected to each other and to the central unit 1 along three branches 11, 12, 13 established so as to minimize the lengths of cables as well as the time

  intervention, and each branch is terminated by an end of branch circuit 3.

  The control unit 1 is equipped so that it can measure the current

  circulating in the electrical connection.

  First of all, when the device is powered up, the control unit measures the standby current flowing in the electrical connection and defines a reference current of

  this link whose value is that of the standby current.

  This reference current is then linked to the standby consumption of all the

  elements 2 of the link and the consumption of all circuits at the end of branch 3.

  Certain elements 2 which can be implemented in the protection circuits are such that their consumption is subject to cyclical variations, it is by

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  example the case of detectors containing a microcontroller which changes regularly between periods of rest and periods of standby. In this case, the value of the reference current of the link is equal to the average value of the standby current measured during a significant reference period, longer than the period of the cyclic variations of the elements. Usually, the reference periods are of the order of

a few seconds.

  When a short circuit occurs in the electrical connection, the control unit 1 detects an increase in the current in said electrical connection and implements a

  limitation or disjunction circuit.

  When the electrical connection is cut, the interface located in the

  control unit 1 measures a decrease in the reference current.

  The decrease in the reference current is observed over a reference period when the device comprises elements 2 whose consumption is the object

cyclical variations.

  Monitoring the current flowing in the electrical connection and comparing it to the reference current makes it possible to know the general state of said electrical connection. When a reduction in the reference current at least equal to that fixed by one of the end-of-branch circuits 3 is detected by the control unit 1, it is certain that at least one of the branches of the installation is cut, means of known type are put

  implemented so as to signal the failure of the electrical connection.

  Preferably, in order to avoid errors in detecting the state of the electrical connection due to a malfunction of one or more elements 2, it will be ensured that the consumption of said elements is very much lower than that of

branch end circuits 3.

  As can be seen in FIGS. 3a to 3c, the topology of the connection established between the elements 2 and the central unit I is carried out freely, the installer looking for the arrangement that is the most economical in terms of time and material. The connection can be completely conventional and comprise a single branch (see FIG. 3a), or comprise several branches each carrying at least one element 2 (see FIG. 3b), or even have branches serving themselves as a starting point for other branches like

  branch 13 of FIG. 3c from which branch 14.

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  In doing so, the device according to the invention allows very great installation flexibility since the number of elements of the circuit and its topology are completely free, the only condition to be respected being the ability of the system to measure a reduction in the standby current. equal to the value of the consumption of a branch end circuit. The arrangement according to the invention in which a reference signal is determined during each commissioning or during each maintenance operation, by the central unit or by an operator, eliminates the need to create links between the consumption of the elements 2 and that of the branch circuit (s) 3 as is necessary in conventional installations. In addition, this makes it possible to temporarily switch off one or more branches of the link when it is not useful to ensure monitoring of the elements 2 that it (s) comprises (s), without disturbing the operation of the device. the fact that the control unit will automatically determine a new reference current during commissioning. This can be useful when you want to leave completely free access to predetermined premises, when you have to

  dismantle elements for an intervention, ...

  In the device according to the invention, the reference current can be fixed by the end of branch circuits 3 permanently or intermittently, either

  cyclically, either at the request of the central.

  Preferably, the consumption of the different end-of-branch circuits present in the link will be provided for different from one another so as to allow the identification of the damaged branch when a break is detected. By way of example, the link shown in FIG. 4 has three different end-of-branch circuits: the circuit 31 has a determined consumption called basic consumption, the consumption of circuit 32 is twice the basic consumption and the consumption of circuit 33 is four times the basic consumption, and the elements 2 have very largely consumption

  lower than those at the end of branch circuits 3.

  Such an arrangement allows the central unit 1 to determine where the electrical connection is cut when it detects a reduction in consumption: - when the reduction is equal to the basic consumption: the section 11 is cut,

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  - when the reduction is equal to twice the basic consumption: the section 12 is cut, - when the reduction is equal to four times the basic consumption: the section, we cut 13, - when the reduction is equal to six times the basic consumption: the section 14 is cut, when the reduction is equal to seven times the basic consumption: the section 10 is cut. The series connection of the different elements of the same branch and the implementation of end-of-branch circuits each corresponding to a control signal therefore makes it possible to ensure complete control of the device by the control unit with a level of security.

quite interesting.

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Claims (13)

  1. - Detection device comprising a central unit (1) and elements (2), for example detectors or sirens, connected to the central unit by an electrical connection comprising at least one branch (11, 12, 13) carrying at least an element (2), characterized in that each branch (11, 12, 13) has an end of branch circuit   (3), each end of branch circuit (3) corresponding to a control signal.   2. - Device according to claim 1, characterized in that each branch (11, 12, 13) is connected, directly or through other branches, to a section (10) connected to the central unit.   3. - A method of implementing the device according to claim 1, characterized in that a reference current is defined, linked to the standby consumption of all the elements (2) of the link and to the consumption of all the circuits of   end of branch (3), equal to the standby current flowing in the electrical connection.   4. - Method according to claim 3, characterized in that the current of   reference is determined automatically by the control unit during each commissioning.   5. - Method according to claim 3, characterized in that the reference signal is determined by an operator during each commissioning or during each maintenance operation.   6. - Method according to any one of claims 3 to 5, characterized in   that, when the device comprises elements whose consumption is subject to cyclical variations, the value of the reference current of the link is equal to the average value of the standby current measured during a significant reference period, plus   longer than the period of cyclical variations.   7. - Method according to any one of claims 3 to 6, characterized in   that when a short circuit occurs in the electrical connection, the control unit detects an increase in the current flowing in the electrical connection and implements a   limitation or disjunction circuit.   8. - Method according to any one of claims 3 to 6, characterized in   that when a break occurs in the electrical connection, the control unit measures a 9 2790 130   reduction of the reference current at least equal to that fixed by one of the circuits end of branch.   9. - Method according to any one of claims 3 to 6, characterized in   what the reference current is fixed by the end of branch circuits permanently.   10. - Method according to any one of claims 3 to 6, characterized   in that the reference current is fixed by the end-of-branch circuits intermittently.   11. - Method according to any one of claims 3 to 6, characterized   in that the reference current is fixed cyclically by the branch end circuits.   12. - Method according to any one of claims 3 to 6, characterized   in that the reference current is fixed by the end-of-branch circuits on demand of the power plant.   13. - Method according to any one of claims 3 to 12, characterized   in that the consumptions of the various end-of-branch circuits (3) present in the connection are provided different from each other so as to allow   identification of the damaged branch when a break is detected.