EP2916303A1 - Field wire detection device and method for fire alarm system - Google Patents

Field wire detection device and method for fire alarm system Download PDF

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Publication number
EP2916303A1
EP2916303A1 EP15157420.9A EP15157420A EP2916303A1 EP 2916303 A1 EP2916303 A1 EP 2916303A1 EP 15157420 A EP15157420 A EP 15157420A EP 2916303 A1 EP2916303 A1 EP 2916303A1
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EP
European Patent Office
Prior art keywords
line
impedance
time points
inter
power supply
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Withdrawn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
EP15157420.9A
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German (de)
English (en)
French (fr)
Inventor
Bing Hai Zhu
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.)
Siemens Schweiz AG
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Siemens Schweiz AG
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Filing date
Publication date
Application filed by Siemens Schweiz AG filed Critical Siemens Schweiz AG
Publication of EP2916303A1 publication Critical patent/EP2916303A1/en
Withdrawn legal-status Critical Current

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    • 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
    • G08B29/12—Checking intermittently signalling or alarm systems
    • G08B29/123—Checking intermittently signalling or alarm systems of line circuits
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B25/00—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems
    • G08B25/01—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems characterised by the transmission medium
    • G08B25/04—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems characterised by the transmission medium using a single signalling line, e.g. in a closed loop
    • 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
    • G08B29/02—Monitoring continuously signalling or alarm systems
    • G08B29/06—Monitoring of the line circuits, e.g. signalling of line faults

Definitions

  • the present invention generally relates to testing of field wires of notification equipment (e.g. a fire alarm device), in particular to detection of line impedance and inter-wire impedance of field wires.
  • notification equipment e.g. a fire alarm device
  • a field device of, for example, an alarm sounder or alarm beacon is connected to a controller (control panel) of the fire alarm system via field wires, also called a line.
  • the controller can supply a drive current to each field device via the line, to make it emit a sound and/or flashing alarm.
  • field wires may develop line open circuits or inter-wire short circuits as a result of wear caused by a long period of use or careless installation.
  • Current safety standards generally all require that a line open circuit fault or an inter-wire short circuit fault be determined relatively accurately, i.e. they require that a fault be reported as soon as it is detected.
  • Fig. 1 shows by way of example a schematic diagram of an existing fire alarm system 100.
  • the fire alarm system 100 comprises a controller 110, one or more field devices 120 connected to the controller 110 via a line (L+, L-), and an End of Line element (EOL) 130 terminally connected to a far end of the line (L+, L-).
  • the field devices 120 are merely shown as loudspeakers by way of example, with diodes for suppressing reverse current being incorporated in the loudspeakers.
  • the field devices could also be alarm beacons (strobes), and could also be field devices that do not incorporate diodes.
  • the EOL in Fig. 1 is generally any resistive element such as a resistor.
  • the controller 110 specifically comprises a driving power supply Vcc-Drive, a monitoring power supply Vcc-Mon, a switching unit 115, a sampling circuit 117, and a control unit (MCU) 113 connected to the switching unit 115 and the sampling circuit 117.
  • the switching unit 115 in Fig. 1 is for example two linked switches K1 and K2.
  • the MCU controls the action of the two switches K1 and K2 in the switching unit 115 through output terminals Ctrl_1 and Ctrl_2 of the MCU.
  • the sampling circuit 117 for example comprises a sampling resistor R1 which can be connected in series on the line. A voltage MON on the sampling resistor R1 can be read by the MCU.
  • the controller 110 can operate in two modes, namely a driving mode and a monitoring mode.
  • the driving mode the MCU 113 controls K1 and K2 to switch to a position 1 as shown in Fig. 1 , i.e. connects the driving power supply Vcc-Drive onto the line, to deliver a forward driving current If.
  • each field device acquires energy from the line L+, L- and operates (e.g. emits sound or light).
  • the number of field devices on the line is related to the driving capacity of the controller and the line loss of the line.
  • the MCU 113 controls K1 and K2 to switch to a position 2 which is opposite to position 1 as shown in Fig. 1 .
  • the monitoring power supply Vcc-Mon (e.g. constant voltage supply) in the controller 110 is connected to the line, to feed a reverse monitoring current Ib onto the line, while the sampling circuit 117 is also connected to the line.
  • the sampling circuit 117 samples the size of the monitoring current on the line. If no valid monitoring current can be read by the MCU 113, this indicates that a line open circuit fault has occurred. If the MCU 113 detects that the current on the line exceeds a predetermined value, this indicates that an inter-wire short circuit fault has occurred.
  • the fire alarm system shown in Fig. 1 determines whether an open circuit or inter-wire short circuit has occurred on the line merely according to the size of current detected on the line.
  • the field line length and the number of field devices vary, there is a need for a method and device for determining line open circuits or inter-wire short circuits more accurately or flexibly.
  • An object of the present invention is to provide a line impedance detection device for a fire alarm system, which device can detect an on-line impedance or inter-wire impedance of a line more accurately, in order to enable a user to distinguish between open circuit and short circuit faults flexibly.
  • a control device for a fire alarm system being capable of driving one or more field devices via a line, and a far end of the line being suitable for connecting to a capacitive element serving as an EOL, characterized in that the control device comprises: a driving power supply, which supplies a driving current to the line for the purpose of driving the one or more field devices, the driving current flowing on the line in a first direction; a monitoring power supply, which can supply a constant monitoring current to the line, the monitoring current flowing on the line in a second direction opposite to the first direction; a sampling circuit, for sampling an output voltage of the monitoring power supply; a controlled switching unit, which can selectively establish an electrical connection from one of the driving power supply and the monitoring power supply to the line; a control unit, which is connected to and controls the switching unit and sampling circuit, the control unit being capable, when the monitoring power supply is connected to the line, of calculating an on-line impedance or inter-wire impedance of the line based on at least
  • control unit comprises: an acquisition unit, which acquires three output voltages sampled at the at least three different time points; a calculating unit, which uses the at least three output voltages obtained by sampling to calculate the on-line impedance or inter-wire impedance of the line, based on Ohm's law for a circuit and a relation between the voltage across a capacitor and a current.
  • n 2
  • control unit also comprises: a determining unit, which determines that an open circuit fault has occurred on the line if the calculated on-line impedance is greater than a predetermined open circuit threshold, or determines that a short circuit fault has occurred on the line if the calculated inter-wire impedance is less than a predetermined short circuit threshold.
  • n 2
  • the method and device proposed in the present invention enables the on-line impedance on a line or inter-wire impedance at the present time to be calculated more accurately and promptly, thereby enabling a judgment to be made more promptly and accurately about whether a short circuit or open circuit fault has occurred.
  • the method and device proposed in the present invention do not need an EOL with a complex structure, and the calculation of on-line impedance or inter-wire impedance is independent of the terminally connected capacitive element.
  • the user can select a suitable capacitive element as an EOL as required, without having a negative impact on the accuracy of line impedance calculation. Therefore the method and device proposed in the present invention are simpler, more convenient and cheaper.
  • the capacitive element is a balanced element, and has a definite advantage with regard to electromagnetic compatibility.
  • n is 2
  • the formulas for calculating on-line impedance and inter-wire impedance are simple, particularly suited to being achieved by the MCU, and place lower demands on the operating capability of the MCU. In other words, precise monitoring of line impedance is possible at a lower cost.
  • Fig. 2 shows the specific structure of a controller 210 according to an embodiment of the present invention.
  • the same labels are used for elements which are the same as in Fig. 1 , and the functions thereof are also similar to those of the elements in Fig. 1 , so will not be repeated here.
  • the EOL in Fig. 2 is a capacitor, not a conventional resistor.
  • a capacitive element 230 may be a commercially available capacitive element, with a range of capacitance of preferably a few hundred ⁇ F, and more preferably between 100 ⁇ F and 470 ⁇ F.
  • the range of capacitance of the capacitive element is not limited to this.
  • Those skilled in the art may select a capacitive element sensibly according to parameters of the MCU.
  • Rc denotes the line resistance of the line
  • Rs denotes the inter-wire resistance.
  • Fig. 2 merely shows the manner of connection in the monitoring mode.
  • K1 and K2 are set so that the monitoring power supply Vcc-Mon (not the driving power supply) in the controller 210 supplies power to the line.
  • the monitoring power supply in the controller 210 is a constant current supply, capable of continuously outputting a constant monitoring current I to the line.
  • a monitoring point P is also provided on the output path of the constant monitoring current I.
  • the monitoring point P is disposed inside the controller, and is also called the on-board monitoring point of the controller 210.
  • the voltage of the monitoring point P is then the output voltage V of the monitoring power supply, and the size of the output voltage V is related to the on-line impedance and inter-wire impedance.
  • the output voltage V at the monitoring point P can be sampled by a sampling circuit 217 and fed back to a monitoring terminal MON of the MCU 213.
  • the monitoring terminal MON may be a port including A/D voltage sampling.
  • the MCU 213 can calculate an inter-wire impedance Rs and on-line impedance Rc on the line.
  • the sampling circuit 217 is preferably an emitter follower circuit, and may also comprise a level conversion circuit or an A/D voltage conversion circuit (when the MCU port does not include A/D conversion), so that the output voltage V obtained by sampling suits the input range of the MCU 213.
  • Vc t IRs ⁇ 1 - e - t CRs
  • C denotes the capacitance of the terminally connected capacitive element C EOL
  • Vc(t) is the voltage across the capacitive element C EOL as a function of time.
  • V I ⁇ Rc + Vc t .
  • V 1 I ⁇ Rc + Vc t 1
  • V 2 I ⁇ Rc + Vc t 2
  • V 3 I ⁇ Rc + Vc t 3
  • Formulas (5 - 7) can be transformed to obtain relations between V 1 - and t 1 - t 3 .
  • Formula (12) is substituted into formula (9) below, allowing the size of Rs to be calculated:
  • Fig. 3 shows by way of example a flow chart of a method for using the abovementioned method of calculating Rc and Rs to determine whether a short circuit or open circuit fault has occurred on the line.
  • the MCU 213 acquires sample output voltages (on-board voltages) V 1 - V 3 at three time points t 1 - t 3 , wherein the time points t 1 - t 3 satisfy the conditions defined by formulas (10 - 11) or formula (16).
  • the MCU 213 uses formulas (13, 15) or formulas (17, 18) to calculate the inter-wire impedance Rs and on-line impedance Rc of the line, respectively.
  • step S330 the MCU 213 compares the calculated Rs with a predetermined short circuit threshold, and if Rs is lower than the short circuit threshold, this indicates that a short circuit fault has occurred on the line.
  • the MCU 213 can also compare the calculated Rc with a predetermined open circuit threshold, and if Rc is larger than the open circuit threshold, this indicates that an open circuit fault has occurred on the line. If it is determined in step S330 that an open circuit or short circuit fault has occurred, the MCU 213 further triggers a line fault alert.
  • Fig. 4 shows by way of example a structural block diagram of the MCU 213 in Fig. 2 .
  • the MCU 213 may comprise a sampling unit 410, a calculating unit 420 and a determining unit 430.
  • the sampling unit 410 acquires sample output voltages (on-board voltages) V 1 - V 3 at three time points t 1 - t 3 , wherein the time points t 1 - t 3 satisfy the conditions defined by formulas (10 - 11) or formula (16).
  • the calculating unit 420 uses formulas (13, 15) or formulas (17, 18) to calculate the inter-wire impedance Rs and on-line impedance Rc of the line, respectively.
  • the determining unit 430 compares the calculated Rs with a predetermined short circuit threshold, and if Rs is lower than the short circuit threshold, this indicates that a short circuit fault has occurred on the line.
  • the determining unit 430 can also compare the calculated Rc with a predetermined open circuit threshold, and if Rc is larger than the open circuit threshold, this indicates that an open circuit fault has occurred on the line.
  • the MCU may also comprise an alert unit 440. Upon receiving a short circuit or open circuit fault signal from the determining unit 430, the alert unit 440 triggers a line fault alert, e.g. an audible and/or optical alert.
  • the method and device proposed in the present invention can calculate more precisely the on-line and inter-wire impedances, and thereby accurately determine whether a fault has occurred on the line.

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  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
  • Alarm Systems (AREA)
EP15157420.9A 2014-03-04 2015-03-03 Field wire detection device and method for fire alarm system Withdrawn EP2916303A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201410076722.5A CN104897967B (zh) 2014-03-04 2014-03-04 火警系统的现场连线检测装置及方法

Publications (1)

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EP2916303A1 true EP2916303A1 (en) 2015-09-09

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EP15157420.9A Withdrawn EP2916303A1 (en) 2014-03-04 2015-03-03 Field wire detection device and method for fire alarm system

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EP (1) EP2916303A1 (zh)
CN (1) CN104897967B (zh)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019224264A1 (de) 2018-05-23 2019-11-28 Minimax Gmbh & Co. Kg Einrichtung, verfahren und steuermodul zur überwachung einer zweidrahtleitung
CN110533873A (zh) * 2019-08-14 2019-12-03 吴飞宇 针对隧道内移动火灾的火焰探测方法
US10762770B1 (en) 2019-05-24 2020-09-01 Honeywell International Inc. Detecting faults on a spur wired alarm circuit
US10977929B2 (en) 2019-05-24 2021-04-13 Honeywell International Inc. Detecting faults on a spur wired alarm circuit
US11287462B2 (en) 2019-07-19 2022-03-29 Carrier Corporation Status detection of alarm sounding parts

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6477753B2 (ja) * 2017-03-15 2019-03-06 ヤマハ株式会社 断線検知装置、信号処理装置、及び断線検知方法

Citations (5)

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Publication number Priority date Publication date Assignee Title
US4529970A (en) * 1982-10-18 1985-07-16 Baker Industries Inc. Supervision system for monitoring the integrity of a transmission line
EP0405247A1 (en) * 1989-06-29 1991-01-02 Nohmi Bosai Ltd. Line interruption supervisory device for fire alarm systems
EP1777671A1 (en) * 2005-10-19 2007-04-25 Honeywell International, Inc. Monitoring of alarm system wiring
US20130147495A1 (en) * 2011-12-12 2013-06-13 Utc Fire & Security Americas Corporation, Inc. End-of-Line Capacitor for Measuring Wiring Impedance of Emergency Notification Circuits
EP2804163A1 (de) * 2013-05-17 2014-11-19 Minimax GmbH & Co KG Verfahren und Vorrichtung zur Störungserkennung auf Steuerleitungen in Gefahrenmelde- und Steuerungssystemen

Family Cites Families (2)

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CN202948530U (zh) * 2012-07-31 2013-05-22 西门子公司 用于火警系统的驱动电路及相应的火警系统
CN103578218B (zh) * 2012-07-31 2016-05-18 西门子瑞士有限公司 火警系统的线路驱动电路及相应的火警系统

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4529970A (en) * 1982-10-18 1985-07-16 Baker Industries Inc. Supervision system for monitoring the integrity of a transmission line
EP0405247A1 (en) * 1989-06-29 1991-01-02 Nohmi Bosai Ltd. Line interruption supervisory device for fire alarm systems
EP1777671A1 (en) * 2005-10-19 2007-04-25 Honeywell International, Inc. Monitoring of alarm system wiring
US20130147495A1 (en) * 2011-12-12 2013-06-13 Utc Fire & Security Americas Corporation, Inc. End-of-Line Capacitor for Measuring Wiring Impedance of Emergency Notification Circuits
EP2804163A1 (de) * 2013-05-17 2014-11-19 Minimax GmbH & Co KG Verfahren und Vorrichtung zur Störungserkennung auf Steuerleitungen in Gefahrenmelde- und Steuerungssystemen

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019224264A1 (de) 2018-05-23 2019-11-28 Minimax Gmbh & Co. Kg Einrichtung, verfahren und steuermodul zur überwachung einer zweidrahtleitung
DE102018112299A1 (de) * 2018-05-23 2019-11-28 Minimax Gmbh & Co. Kg Einrichtung, Verfahren und Steuermodul zur Überwachung einer Zweidrahtleitung
DE102018112299B4 (de) * 2018-05-23 2020-12-03 Minimax Gmbh & Co. Kg Einrichtung, Verfahren und Steuermodul zur Überwachung einer Zweidrahtleitung
US11210930B2 (en) 2018-05-23 2021-12-28 Minimax Gmbh Device, method, and control module for monitoring a two-wire line
US10762770B1 (en) 2019-05-24 2020-09-01 Honeywell International Inc. Detecting faults on a spur wired alarm circuit
US10977929B2 (en) 2019-05-24 2021-04-13 Honeywell International Inc. Detecting faults on a spur wired alarm circuit
US11287462B2 (en) 2019-07-19 2022-03-29 Carrier Corporation Status detection of alarm sounding parts
CN110533873A (zh) * 2019-08-14 2019-12-03 吴飞宇 针对隧道内移动火灾的火焰探测方法

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CN104897967B (zh) 2019-02-01
CN104897967A (zh) 2015-09-09

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