EP0980056A1 - Alarmsystem - Google Patents

Alarmsystem Download PDF

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Publication number
EP0980056A1
EP0980056A1 EP98306414A EP98306414A EP0980056A1 EP 0980056 A1 EP0980056 A1 EP 0980056A1 EP 98306414 A EP98306414 A EP 98306414A EP 98306414 A EP98306414 A EP 98306414A EP 0980056 A1 EP0980056 A1 EP 0980056A1
Authority
EP
European Patent Office
Prior art keywords
voltage
warning device
output
power supply
alarm system
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98306414A
Other languages
English (en)
French (fr)
Inventor
Manhar Amlani
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rafiki Protection Ltd
Original Assignee
Rafiki Protection Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to GB9709207A priority Critical patent/GB2325074A/en
Application filed by Rafiki Protection Ltd filed Critical Rafiki Protection Ltd
Priority to EP98306414A priority patent/EP0980056A1/de
Publication of EP0980056A1 publication Critical patent/EP0980056A1/de
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
    • G08B29/18—Prevention or correction of operating errors
    • G08B29/181—Prevention or correction of operating errors due to failing power supply

Definitions

  • This invention relates to an alarm system.
  • Alarm systems are known which comprise audible and/or visual warning devices which are activated in the event that an alarm condition is detected. It is well known to provide alarm systems with back-up batteries, which enable the system remain functional when there is a loss of mains power.
  • the back-up battery In fire alarms systems for hotels and other residences, there is a requirement that the back-up battery must be able to provide sufficient power after 72 hours that audible warning devices in each room can output a volume of at least 75dB, when monitored from a point located at the head of the bed in that room. Thus, if a fault occurs with the supply to the alarm system, the back-up battery should have sufficient power for the alarm system to remain operational until the fault is detected and rectified.
  • Alarm systems consume a considerable amount of power when in the stand-by mode and thus it is difficult for back-up batteries to meet the above-mentioned objective.
  • the problem can be solved by providing a large back-up battery, or by limiting the number of alarm detectors connected to the system, so that less current is consumed in the stand-by mode.
  • Another problem with alarm systems is that there is often several kilometres of cable between the audible warning devices and the control panel.
  • the cable exhibits electrical resistance, with the result that there can be a considerable voltage drop along the cable, particularly when a high current is being drawn during an alarm condition. Accordingly, there is a risk that the alarm voltage at the audible warning devices will be considerably than their proper operating voltage, with the result that the output noise level of the audible warning devices will be considerably less than is required.
  • an alarm system comprising a warning device and power supply means for providing power to the warning device, wherein the normal output voltage of said power supply means substantially exceeds a set voltage at which an output of the warning device is at a predetermined acceptable level.
  • the output of the warning device at said level is arranged so that it is sufficient to alert persons that an alarm condition has been detected.
  • the output level of the warning device will remain at said acceptable level as long as the output voltage of the power supply substantially exceeds the set voltage.
  • the warning device is connected to the power supply means via a voltage regulator means, which provides the warning device with the set voltage when the output of the power supply means is greater than the set voltage.
  • a voltage regulator means which provides the warning device with the set voltage when the output of the power supply means is greater than the set voltage.
  • the output level of the warning device does not fall as the output voltage of the power supply means falls towards the set voltage.
  • the voltage regulator means outputs an alternating voltage such as a square wave, the regulator means being arranged to stabilise the average value of the alternating voltage, in order to provide the warning device with the set voltage.
  • the voltage regulator means will vary the mark-to-space ratio of the regulator voltage, thereby stabilising its average value.
  • the voltage regulator means is arranged to output a d.c. voltage having a value which remains at the set voltage of the warning device, as long as the output voltage of the power supply means remains at or above the set voltage.
  • the warning device comprises an audible warning device.
  • the power supply means comprises a rechargeable battery.
  • a fire alarm system comprising a control panel 10 having a power supply 12 provided with terminals 11 for connecting to the mains supply.
  • a rechargeable battery 13 is connected to the power supply 12, and is arranged to provide power in the event of an interruption in the mains supply.
  • a plurality of sounders e.g. 16 are connected in parallel across a pair of wires 14, 15 that extend from the control panel 10.
  • the sounders 16 each comprise a speaker 18 and a speaker driver circuit (not shown), which is connected to the wires 14, 15 via a voltage regulator 17.
  • the speaker 18 is arranged to produce an output of 75dB, when a voltage of say 6 volts is applied to the driver circuit.
  • the alarm system also comprises a plurality of heat and/or smoke sensors and manual call points (not shown), which are connected to the control panel 10.
  • the control panel 10 enters an alarm condition when one of the sensors or call points is activated, whereupon it applies an alarm signal to the wires 14, 15.
  • the alarm signal comprises a d.c. voltage of a value which is normally much greater than 6 volts.
  • the voltage regulator 17 produces a voltage on its output which is regulated at 6 volts.
  • the speaker 18 generates an audible warning signal at 75dB.
  • the battery 13 maintains the supply, so that the alarm remains operational.
  • the control panel 10 and the detectors draw current from the battery in the standby mode of the alarm, and thus the battery 13 slowly becomes exhausted.
  • the output voltage of the battery 13 fall as the battery becomes exhausted, which causes a corresponding reduction in the alarm voltage.
  • the output level of the speakers 18 will fall as the battery becomes exhausted.
  • the speakers 18 of an alarm system in accordance with this invention will continue to operate at 75 db, as long as the battery 13 can produce an alarm voltage of 6 volts or more.
  • the alarm voltage and battery voltage are equal to 24 volts.
  • the battery voltage has to fall from 24 volts to 6 volts before the output level of the speaker starts to fall.
  • the regulator 17 produces a square wave on its output, having a peak-to-peak value which is dependent on the alarm voltage.
  • the average voltage value of the square wave is adjusted by the regulator to 6 volts.
  • the regulator increases the mark-to-space ratio of the square wave, in order to keep the mean value of the square wave at 6 volts.
  • FIG. 2 of the drawings there is shown an alternative embodiment of alarm system and like parts are given like reference numerals.
  • a supply of voltage is continuously applied to the wires 14, 15, the sounders 16 being activated by applying an alarm signal to a third wire 20.
  • the sounders 16 are activated current is drawn from the wires 14, 15.
  • the supply voltage on the wires 14, 15 will fall as the battery voltage falls, although the voltage of the alarm signal may not fall.
  • the regulator 17 and speaker 18 operate in the same way as before, and thus the output of the speaker will remain at 75dB until the supply voltage on the wires 14, 15 falls below 6 volts.
  • the wires 14, 15 continuously carry a supply of voltage, say to power detectors which may be incorporated within the same housing as the sounders 16, and the sounders are activated by superimposing an a.c. alarm signal onto the supply voltage.
  • the sounders 16 comprise a detector circuit which monitors the wires 14, 15 and activates the speakers in the event that the a.c. alarm signal is detected.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fire Alarms (AREA)
  • Alarm Systems (AREA)
EP98306414A 1997-05-08 1998-08-11 Alarmsystem Withdrawn EP0980056A1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB9709207A GB2325074A (en) 1997-05-08 1997-05-08 Fire alarm system
EP98306414A EP0980056A1 (de) 1997-05-08 1998-08-11 Alarmsystem

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9709207A GB2325074A (en) 1997-05-08 1997-05-08 Fire alarm system
EP98306414A EP0980056A1 (de) 1997-05-08 1998-08-11 Alarmsystem

Publications (1)

Publication Number Publication Date
EP0980056A1 true EP0980056A1 (de) 2000-02-16

Family

ID=26151393

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98306414A Withdrawn EP0980056A1 (de) 1997-05-08 1998-08-11 Alarmsystem

Country Status (2)

Country Link
EP (1) EP0980056A1 (de)
GB (1) GB2325074A (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2931981A1 (fr) * 2008-05-28 2009-12-04 Denis Dutrop Dispositif d'alarme avec autotest

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2745292A1 (de) * 1977-10-07 1979-04-12 Preussag Ag Feuerschutz Spannungsversorgungseinrichtung fuer die zentrale einer meldeanlage
DE8411757U1 (de) * 1984-04-14 1984-08-09 Schmickler, Günther, 4006 Erkrath Signaleinrichtung, insbesondere akustisches alarmgeraet
US4499453A (en) * 1982-05-28 1985-02-12 General Signal Corporation Power saver circuit for audio/visual signal unit
US4929924A (en) * 1989-01-27 1990-05-29 General Signal Corporation Electronic alarm horn
US4954805A (en) * 1990-02-06 1990-09-04 General Signal Corporation Piezo electronic horn
US5160913A (en) * 1987-10-19 1992-11-03 Sparton Corporation Electric horn with solid state driver
WO1998011666A1 (en) * 1996-09-11 1998-03-19 Robert Bosch Gmbh A sounder control system

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9418719D0 (en) * 1994-09-16 1994-11-02 Jsb Electrical Plc Fire alarms

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2745292A1 (de) * 1977-10-07 1979-04-12 Preussag Ag Feuerschutz Spannungsversorgungseinrichtung fuer die zentrale einer meldeanlage
US4499453A (en) * 1982-05-28 1985-02-12 General Signal Corporation Power saver circuit for audio/visual signal unit
DE8411757U1 (de) * 1984-04-14 1984-08-09 Schmickler, Günther, 4006 Erkrath Signaleinrichtung, insbesondere akustisches alarmgeraet
US5160913A (en) * 1987-10-19 1992-11-03 Sparton Corporation Electric horn with solid state driver
US4929924A (en) * 1989-01-27 1990-05-29 General Signal Corporation Electronic alarm horn
US4954805A (en) * 1990-02-06 1990-09-04 General Signal Corporation Piezo electronic horn
WO1998011666A1 (en) * 1996-09-11 1998-03-19 Robert Bosch Gmbh A sounder control system

Also Published As

Publication number Publication date
GB2325074A (en) 1998-11-11
GB9709207D0 (en) 1997-06-25

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