METHOD FOR DETERMINING THRESHOLDS OF A STATE MONITORING UNIT FOR A FIRE DETECTION AND/OR EXTINGUISHING CONTROL CENTER, STATE MONITORING UNIT, AND SYSTEM COMPRISING SAME

Abstract

The invention relates to a condition monitoring unit (18) for a fire detection and/or extinguishing control unit (12). The condition monitoring unit (18) comprises at least one current circuit connection (16) for connecting the condition monitoring unit (18) to at least one current circuit (14), wherein the current circuit (14) has at least one participant (M.sub.1-M.sub.N) which detects an event. The condition monitoring unit (18) further comprises a measuring device (42) for measuring values of currents (I.sub.L) and/or voltages at the current circuit connection (16) and an analysis unit (43) in which one or more threshold values (P.sub.1, P.sub.2) can be stored. The analysis unit (43) is designed to detect, in an operating mode at least, an event in which values of currents (I.sub.L) and/or voltages measured by the measuring device (42) exceed or fall below the at least threshold value (P.sub.1, P.sub.2). The condition monitoring unit (18) further comprises a memory unit (41) or an interface (20) for transmitting data to an external memory unit, wherein the condition monitoring unit (18) is designed to store values of the currents (I.sub.L) and/or voltages measured by the measuring device (42) in the memory unit (41), in a learning mode at least, or to output the values via the interface (20) to the external memory unit and to determine or change the threshold values (P.sub.1, P.sub.2) depending on the stored values of the currents (I.sub.L) and/or voltages.

The invention also relates to a method for determining threshold values for a condition monitoring unit (18) for a fire detection and/or extinguishing control unit (12), to a fire detection and/or extinguishing control unit (12) and to a fire detection system (10).

Claims

1. A condition monitoring unit for a fire detection and/or extinguishing control unit, comprising: at least one current circuit connection for connecting the condition monitoring unit to at least one current circuit, wherein the current circuit has at least one participant which detects an event, a measuring device for measuring values of currents and/or voltages at the current circuit connection, an analysis unit in which one or more threshold values can be stored, wherein the analysis unit is designed to detect, in an operating mode at least, an event in which values of currents and/or voltages measured by the measuring device exceed or fall below the at least one threshold value, a memory unit or an interface for transmitting data to an external memory unit, wherein the condition monitoring unit is designed to store values of the currents and/or voltages measured by the measuring device in the memory unit, in a learning mode at least, or to output the values via the interface to the external memory unit and to determine or change the threshold values depending on the stored values of the currents and/or voltages.

2. The condition monitoring unit according to claim 1, wherein the condition monitoring unit is designed to determine or change the threshold value(s) depending on the stored values of the currents and/or voltages, to determine a frequency distribution of the measured values of the currents and/or voltages and to select for threshold value(s) those values of the currents and/or voltages which correspond respectively to a minimum in the frequency distribution and/or which correspond respectively to a mean value between adjacent maxima in the frequency distribution.

3. The condition monitoring unit according to claim 1, wherein the learning mode further comprises: a first subordinate mode which is designed to detect a quiescent value by determining a maximum in the frequency distribution of all the values of the currents and/or voltages measured in the first subordinate mode and/or a second subordinate mode which is designed to detect a first event value by determining a maximum in the frequency distribution of all values of the currents and/or voltages measured in the second subordinate mode, and/or a third subordinate mode which is designed to detect a second event value by determining a maximum in the frequency distribution of all the values of the currents and/or voltages recorded in the third subordinate mode.

4. The condition monitoring unit according to claim 3, wherein the condition monitoring unit is designed to determine a first threshold value equal to an arithmetical mean of the quiescent value and the first event value and/or to determine a second threshold value equal to an arithmetical mean of the first event value and the second event value.

5. The condition monitoring unit according to claim 4, wherein the condition monitoring unit includes a test mode for testing whether all the values of the currents and/or voltages measured in the first subordinate mode are below the first threshold value and/or all the values of the currents and/or voltages measured in the second subordinate mode are above the first threshold value and/or all the values of the currents and/or voltages measured in the second subordinate mode are below the second threshold value and/or all the values of the currents and/or voltages measured in the third subordinate mode are above the second threshold value.

6. The condition monitoring unit according to claim 1, wherein the condition monitoring unit is designed to store, in the memory unit, values of the currents and/or voltages which are measured at intervals or continuously in the operating mode and/or to output the values via the interface to the external memory unit and to determine or change the threshold value(s) automatically during the operating mode and/or to allow the user to determine or change the values measured at intervals or continuously, when manually requested in the operating mode or in the learning mode.

7. The condition monitoring unit according to claim 1, wherein the condition monitoring unit is designed to display, for the user, the threshold value(s) calculated for the purpose of determining or changing, when manually requested by a user to determine or change the threshold value(s), or to output them via an interface for display, for example on a display device, and/or to receive user commands via the interface or input means in order, depending on the commands, to change one or more stored threshold values by replacing them with the calculated threshold value(s), to delete one, all or a plurality of the threshold value(s) and/or the stored values of the currents and/or voltages, and/or to switch between the modes.

8. A method for determining at least one threshold value for a condition monitoring unit for a fire detection and/or extinguishing control unit, wherein values of currents and/or voltages at least one current circuit connection of the condition monitoring unit are measured by means of a measuring device, wherein, in an operating mode at least, an event in which values of currents and/or voltages measured by the measuring device exceed or fall below the at least one threshold value is detected by an analysis unit, wherein the measured values of the currents and/or voltages are stored in a memory unit, in a learning mode at least, or the values are outputted via an interface to the external memory, and at least one threshold value is determined or changed depending on the stored values of the currents and/or voltages.

9. The method according to claim 8, wherein a frequency distribution of the measured values of the currents and/or voltages is determined in order to determine or change the threshold value(s) depending on the stored values of the currents and/or voltages, and the values of the currents and/or voltages which correspond respectively to a minimum in the frequency distribution and/or which correspond respectively to a mean value between adjacent maxima in the frequency distribution are selected for threshold value(s).

10. The method according to claim 8, wherein in a first subordinate mode of the learning mode, a quiescent value is detected by determining a maximum in the frequency distribution of all the values of the currents and/or voltages measured in the first subordinate mode and/or in a second subordinate mode of the learning mode, a first event value is detected by determining a maximum in the frequency distribution of all the values of the currents and/or voltages measured in the second subordinate mode, and/or in a third subordinate mode of the learning mode, a second event value is detected by determining a maximum in the frequency distribution of all the values of the currents and/or voltages measured in the third subordinate mode.

11. The method according to claim 10, wherein a first threshold value is determined which is equal to an arithmetical mean of the quiescent value and the first event value and/or a second threshold value is determined which is equal to an arithmetical mean of the first event value and the second event value.

12. The method according to claim 11, wherein tests are performed in a test mode to determine whether all the values of the currents and/or voltages measured in the first subordinate mode are below the first threshold value and/or all the values of the currents and/or voltages measured in the second subordinate mode are above the first threshold value and/or all the values of the currents and/or voltages measured in the second subordinate mode are below the second threshold value and/or all the values of the currents and/or voltages measured in the third subordinate mode are above the second threshold value.

13. The method according to claim 1, wherein in the operating mode, values of the currents and/or voltages are stored at intervals or continuously in the memory unit, or are automatically outputted via the interface to the external memory unit during operation, and/or are determined or changed by manual request in the operating mode or in the learning mode.

14. The method according to claim 1, wherein when a user manually requests to determine or change the threshold value(s), the threshold value(s) calculated for the purpose of determining or changing are displayed or outputted via an interface to the display device and/or user commands are received via the interface or input means in order, depending on the commands, to change one or more stored threshold values by replacing them with the calculated threshold values, to delete one, all or a plurality of the threshold value(s) and/or the stored values of the currents and/or voltages, and/or to switch between the modes.

15.-16. (canceled)

Description

[0044] Other embodiments are derived from the embodiments that are described in detail with reference to the drawings. In the drawings,

[0045] FIG. 1 shows an embodiment of a fire detection system,

[0046] FIG. 2 shows an enlarged view of an embodiment of a condition monitoring unit and

[0047] FIG. 3 shows a measured frequency distribution and the determination of values and threshold values.

[0048] FIG. 1 shows a fire detection system 10 comprising a fire detection and/or extinguishing control unit 12. Fire detection system 10 further comprises a current circuit 14 which includes a two-wire circuit, wherein the lines of the two-wire circuit are connected to each other at one end across a terminating resistor R.sub.EOL. At the another end, the lines of the two-wire circuit are connected by a current circuit connection 16 to a condition monitoring unit 18.

[0049] The condition monitoring unit 18 is a separate unit, for example, e.g. a module, and is provided, in particular, in the form of a top hat rail module which can be snapped onto a top hat rail of the fire detection and/or extinguishing control unit 12. The condition monitoring unit 18 is connected by a bus system interface via an internal bus to a superordinate processor unit 22 by means of an interface 20. The bus system interface is preferably mounted on the housing of the top hat rail module that includes the condition monitoring unit 18.

[0050] In one advantageous embodiment, the condition monitoring unit 18 comprises at least one electronic flat module, or some other integration of electronic components, for example a system-on-chip which includes all the electronic components and modules that are necessary for the condition monitoring unit 18 to function. The electronic components will be described in detail further below with reference to FIG. 2.

[0051] An interface 20 and a superordinate processor unit 22 are also provided. The superordinate processor unit 22 is not part of the condition monitoring unit 18, but is merely connected via the interface to the condition monitoring unit 18. A display device 24 is also connected to the superordinate processor unit 22. Input means 26 with which user commands can be inputted via interface 20 to the condition monitoring unit 18 by means of the superordinate processor unit 22 are also provided. Input means 26 are also used, for example, to configure the fire detection and/or extinguishing control unit 12. Display device 24 is used to display the configuration and to display the operating mode of the fire detection and/or extinguishing control unit 12, or the different modes that are selected by means of input means 26.

[0052] Current circuit 14, which is connected via the current circuit connection 16 to the condition monitoring unit 18, is connected to participants M.sub.1ccM.sub.N. The participants are thus connected in parallel to terminating resistor R.sub.EOL. Resistors R.sub.L1a-R.sub.LNa and R.sub.L1b-R.sub.LNb are the line resistances between the individual participants M.sub.1-M.sub.N. Each participant M.sub.1-M.sub.N has an energy sink (not shown) and an element (not shown) for detecting events. This element is a sensor, for example, which detects fire parameters such as temperature, smoke aerosols, electromagnetic radiation from flames, sparks or pockets of embers or fire gases, or a simple switch that registers changes in the switch positions of components in fire-extinguishing systems, for example in valve positioning monitoring where the switch is opened or closed by the valve opening or closing, in order to detect an event in this way.

[0053] The participants are thus used for various different purposes within the fire detection system, for example as: [0054] limit switches for detecting the position of ball valves, shut-off valves, shut-off flaps or slides; [0055] manometric switches for measuring air pressure, e.g. in compressed air water containers or in the dry pipe network; [0056] float switches for measuring filling levels in compressed air water container, unpressurised water containers and other vessels for storing extinguisher fluid; [0057] temperature switches, for example for monitoring the ambient temperature in a sprinkler station; [0058] pump pressure switches for starting the sprinkler pump motor in response to a pressure drop in the pipe network for extinguisher fluid, or in a tap; [0059] fire alarms, such as automatic fire alarms or manual call points, and sensors for registering event alarms, fire alarms and malfunctions.

[0060] Customary standards allow up to 32 participants M.sub.1-M.sub.N to be used on a current increase circuit, namely current circuit 14. They may be placed anywhere in the current increase circuit, that is in current circuit 14, which is designed here as a two-wire circuit. In the simplest case, participants M.sub.1-M.sub.N may be provided in the form of a switch and a resistor connected in series, for example a 470? resistor. When the switch is closed in the case of an alarm, this causes an increase in current, for example an increase of 18 mA, which can be detected by the condition monitoring unit 18.

[0061] Applicable standards propose methods for preventing false alarms. One method expects there to be at least two simultaneously triggered participants M.sub.1-M.sub.N. In this case, a current ensues which is arithmetically higher than when only one participant is triggered. A current of 41 mA is possible here, for example.

[0062] Resistors R.sub.L1a-R.sub.LNa and R.sub.L1b-R.sub.LNb are not taken into account in the latter current values. When they are taken into account, the currents measured by the condition monitoring unit 18 also depend on whether the two participants M.sub.1-M.sub.N which detect an event are located at the start of current circuit 14, i.e. near condition monitoring unit 18, or at the end, i.e. near terminating resistor R.sub.EOL.

[0063] Besides the alarms or events in which one or more participants M.sub.1-M.sub.N are in the alarm condition, i.e. have detected an event, the condition monitoring unit 18 must also detect disturbances in current circuit 14. If the current drops far below the quiescent current, which is 5 mA for example, then this is an indication that current circuit 14 has been interrupted. If the current increases to higher levels, the condition monitoring unit 18 can assume that there is a short circuit in current circuit 14.

[0064] The condition monitoring unit 18 therefore serves to detect events by providing a substantially constant line voltage UL for current circuit 14. A normal voltage level is around 9 V, although levels of up to 24 V are common. Terminating resistor R.sub.EOL has an impedance of 1.8 k?, for example.

[0065] The conducting wires of current circuit 14 have a cross-section of 0.8 mm.sup.2, for example, and therefore have a resistance of approximately 4? per 100 m length at 20?. That resistance is not constant, however, but can vary with temperature. In the case of the aforementioned wire cross-section, the resistance varies by more than 50 m? over a loop length of 100 m and a temperature difference of 10?. In practice, cable paths are up to 1,000 m long in many cases. The current I.sub.L flowing through current circuit 14 is therefore measured by the condition monitoring unit and varies according to temperature, for example, as noted above.

[0066] FIG. 2 shows the detailed structure of a condition monitoring unit 18. The condition monitoring unit 18 has a current circuit connection 16 which is connected to a signal processor 30. Signal processor 30 contains filters, for example, for smoothing the voltages and currents in current circuit 14.

[0067] A voltage source 32 is also provided, by means of which a voltage, for example of 9 V, can be applied to current circuit connection 16. A shunt resistor 34 is also provided between voltage source 32 and current circuit connection 16. This resistor is used for measuring current. When a current flows through current circuit 14, which is connected at current circuit connection 16, there is a drop in voltage across shunt resistor 34. This drop in voltage is sensed with the aid of a current measurement stage 36 and supplied to an analogue/digital converter 38 of a processor unit 40. Shunt resistor 34, current measurement stage 36 and A/D converter 38 form a measuring device 42.

[0068] As a voltage drops across shunt resistor 34, a feedback line 44 is provided to readjust voltage source 32 so that a substantially constant voltage is applied at the current circuit connection 16. Processor unit 40 is connected to a memory unit 41. Processor unit 40 and memory unit 41 form an analysis unit 43. In a learning mode, analysis unit 43 is used to store currents I.sub.L measured by measuring device 42. The values of currents I.sub.L through current circuit 14, which are measured in the learning mode by means of measuring device 42, are stored in the memory unit 41 of analysis unit 43.

[0069] By means of measuring device 42, it is thus possible to measure different current values which occur when an event is detected by a participant M.sub.1-M.sub.N, or when no event is detected.

[0070] Threshold values are calculated, depending on the values that are stored. These threshold values are used later to distinguish between different currents in the current circuit, namely a quiescent current at which no participant M.sub.1-M.sub.N has detected an event, a first event value at which a single participant has detected an event, and a second event value at which at least two participants M.sub.1-M.sub.N have detected an event.

[0071] It shall now be described in detail how the threshold values are determined by analysis unit 43. Reference is made in this regard to FIG. 3.

[0072] In the first step, a first threshold value P.sub.1 is determined.

[0073] To do so, the frequency distribution 50 of a quiescent value I.sub.R is determined, in a learning mode, by recording values of current I.sub.L in a first subordinate mode by means of the analysis unit 43 of condition monitoring unit 18. The duration of such recording, i.e. the period for which the measured values are stored, can be either a predefined or an arbitrary duration, for example from installation to entry into service of the fire detection and/or extinguishing control unit 12. Frequency distribution 50 is used to calculate a maximum 52, which is then defined as quiescent value I.sub.R.

[0074] In the step that follows, in a second subordinate mode, all the participants M.sub.1-M.sub.N connected to current circuit 14 are individually put into the alarm condition, i.e. in such a way that they detect an event. Current values I.sub.L are measured again and stored in memory unit 41. Frequency distribution 54 is then determined in the basis of those values. Frequency distribution 54 is likewise used to calculate maximum 56, which is then defined as the first event value I.sub.E1. The arithmetic mean of quiescent value I.sub.R and the first event value I.sub.E1 is then determined. That mean is defined as the first threshold value P.sub.1.

[0075] In a test mode, tests are then performed to determine whether all the values measured in the first subordinate mode are below P.sub.1 and all the values measured in the second subordinate mode are above P.sub.1. If that is not the case, an error message is outputted by analysis unit 43.

[0076] A second threshold value P.sub.2 is also determined, in a third subordinate mode, by successively triggering two participants M.sub.1-M.sub.N simultaneously. At least the two participants M.sub.1-M.sub.N which are closest to the fire detection and/or extinguishing control unit 12 in current circuit 14 are triggered, as well as the two participants M.sub.1-M.sub.N which are closest to terminating resistor R.sub.EOL in current circuit 14. Other combinations thereof are likewise advantageous. These values are then used to generate another frequency distribution 58 based on the values stored in the third subordinate mode, and a maximum 60 is also determined on the basis of that frequency distribution 58. This maximum 60 is then defined as the second event value I.sub.E2.

[0077] In the next step, threshold value P.sub.2 is calculated as the arithmetic mean between the first event value I.sub.E1, the one determined in the second subordinate mode, and the second event value I.sub.E2, the one determined in the third subordinate mode. Processor unit 40 again checks whether all the values measured in the second subordinate mode are below the second threshold value P.sub.2 and all the values measured in the third subordinate mode are above the second threshold value P.sub.2. In the event of any error, this is signalled accordingly.

[0078] Ranges 62 to 66 are thus defined. These ranges correspond to ranges of current values to be assigned to different events. Ranges 62 to 66 are separated from each other by threshold values P.sub.1 and P.sub.2. In range 62, for example, it is assumed that no event has occurred and that a quiescent condition is present. In range 64, it is then assumed that an event detected by a participant M.sub.1-M.sub.N has occurred. The adjoining range 66 is then a range of current values in which at least two participants M.sub.1-M.sub.N have triggered.

[0079] Threshold values P.sub.0 and P.sub.KS are also entered. If a current below the value P.sub.0 is detected by measuring device 42, there is a broken wire. If a value above threshold value P.sub.KS is measured, a short-circuit is assumed. Values P.sub.0 and P.sub.KS are permanently preset, for example, in memory unit 41.

[0080] Threshold values P.sub.1 and P.sub.2 for distinguishing between a quiescent condition or an event condition can thus be determine in a simple and particularly precise and reliable manner and can be stored in memory unit 41 once they have been determined.