EP0498619A2 - Verfahren und Schaltungsanordnung für Flammendetektor - Google Patents

Verfahren und Schaltungsanordnung für Flammendetektor Download PDF

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Publication number
EP0498619A2
EP0498619A2 EP92300935A EP92300935A EP0498619A2 EP 0498619 A2 EP0498619 A2 EP 0498619A2 EP 92300935 A EP92300935 A EP 92300935A EP 92300935 A EP92300935 A EP 92300935A EP 0498619 A2 EP0498619 A2 EP 0498619A2
Authority
EP
European Patent Office
Prior art keywords
flame
probe
node
impedance
detection circuit
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Withdrawn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
EP92300935A
Other languages
English (en)
French (fr)
Other versions
EP0498619A3 (en
Inventor
Patrick James Mcgrath
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.)
Black Automatic Controls Ltd
Original Assignee
Black Automatic Controls 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
Application filed by Black Automatic Controls Ltd filed Critical Black Automatic Controls Ltd
Publication of EP0498619A2 publication Critical patent/EP0498619A2/de
Publication of EP0498619A3 publication Critical patent/EP0498619A3/en
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/02—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
    • F23N5/12—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using ionisation-sensitive elements, i.e. flame rods
    • F23N5/123—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using ionisation-sensitive elements, i.e. flame rods using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2229/00—Flame sensors

Definitions

  • This invention relates to flame detection circuits and methods.
  • Known flame detection circuits include a flame probe comprising two electrodes which are positioned where a flame is expected. The ionising effect of a flame in the region of the probe causes an alternating voltage applied across the probe to be partially rectified, the D.C. component thus produced providing an indication of whether a flame is in fact present.
  • the first circuit to be described includes a flame probe comprising two electrodes 1,3.
  • An A.C. voltage is applied across the electrodes 1,3 by means of a terminal 5 for connection to the live rail 5 of an A.C. supply via a capacitor 7 and a resistor 9, the electrode 1 being earthed via the metalwork of the burner (not shown) for producing a flame.
  • Any D.C. offset generated by the flame probe 1,3 due to the presence of a flame is amplified by a D.C. amplifier 11, connected to the node between the capacitor 7 and resistor 9 by a further resistor 13, and measured with respect to earth.
  • FIG 2 which is an adaptation of the circuit of Figure 1, and in which corresponding components to those in Figure 1 are correspondingly labelled.
  • the primary winding 15 of a transformer is connected across two terminals 5,17, these being intended for connection to the live 5 and neutral 17 rails respectively of an A.C. supply.
  • the flame probe 1,3 is connected across a secondary 18 of the transformer, the output of the transformer being referenced to earth.
  • a flame detection circuit comprising a flame probe, means for applying an alternating voltage across the flame probe, and means responsive to the D.C. component induced by the flame probe in the presence of a flame to provide an indication of whether a flame is present in the vicinity of the flame probe, the circuit being characterised in that the means for applying an alternating voltage comprises: a pair of terminals for connection to the two supply rails of an A.C. supply, impedance means connected across the terminals, and an A.C. current path between a node in the impedance means and the flame probe such that the impedances between the node and each terminal are substantially equal.
  • a flame detection method using a flame probe in which an alternating voltage is applied across the flame probe, and the D.C. component induced by the flame probe in the presence of a flame is monitored to provide an indication of whether a flame is present in the vicinity of the flame probe, the method being characterised by the steps of connecting an impedance means across the two supply rails of an A.C. supply, and providing an A.C. current path between a node in the impedance means and the flame probe, such that the impedance between the node and each supply rail is substantially equal.
  • the embodiment of a flame detection circuit in accordance with the invention is an adaptation of the circuit of Figure 2 and thus corresponding components are correspondingly labelled.
  • the transformer 15,18 of the circuit shown in Figure 2 is, however, replaced by a pair of equal valued resistors 19,21 connected across the terminals 5,17, with the node between the resistors 19,21 being connected to the capacitor 7.
  • the A.C. voltage supplied to the flame probe is derived from both the live and neutral rails.
  • the amplitude of the voltage supplied to the probe will thus be equal to half that of the A.C. supply voltage.
  • the resultant reduction in the magnitude of the D.C. current produced by the flame probe 1,3, in the presence of a flame may be compensated for by increasing the sensitivity of the D.C. amplifier 23 used to amplify the D.C. current to twice that of the corresponding amplifier 11 incorporated in the circuits shown in Figures 1 and 2.
  • the impedance of each resistor 19,21 should be chosen to be 10% or less of the impedance of the capacitor 7.
  • the output of the amplifier 23 may be used in a suitable control circuit (not shown) for controlling, for example, a gas supply valve dependent on whether the flame detection circuit provides a signal indicative of the presence of a flame in the vicinity of the flame probe 1,3.
  • a suitable control circuit is described in our co-pending European patent application No. 91308843

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Combustion (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
EP19920300935 1991-02-04 1992-02-04 Flame detection circuit and method Withdrawn EP0498619A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9102372 1991-02-04
GB9102372A GB2252436A (en) 1991-02-04 1991-02-04 Flame detection circuit and method

Publications (2)

Publication Number Publication Date
EP0498619A2 true EP0498619A2 (de) 1992-08-12
EP0498619A3 EP0498619A3 (en) 1993-05-19

Family

ID=10689508

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19920300935 Withdrawn EP0498619A3 (en) 1991-02-04 1992-02-04 Flame detection circuit and method

Country Status (2)

Country Link
EP (1) EP0498619A3 (de)
GB (1) GB2252436A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19712938C1 (de) * 1997-03-27 1998-05-14 Honeywell Bv Schaltungsanordnung zum Erzeugen einer Speisewechselspannung für den Flammenstab eines Flammenwächters
DE10202910C1 (de) * 2002-01-25 2003-10-16 Honeywell Bv Schaltungsanordnung zur Ermittlung des Flammenstromes eines Brenners
CN113452328A (zh) * 2021-06-30 2021-09-28 黄俊融 一种信号放大模块及火焰检测电路

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU552083B2 (en) * 1980-09-25 1986-05-22 Philips Electronics Australia Limited Flame monitoring circuit
NL8401173A (nl) * 1984-04-12 1985-11-01 Philips Nv Vlambeveiligingsschakeling.
US4872828A (en) * 1987-09-10 1989-10-10 Hamilton Standard Controls, Inc. Integrated furnace control and control self test

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19712938C1 (de) * 1997-03-27 1998-05-14 Honeywell Bv Schaltungsanordnung zum Erzeugen einer Speisewechselspannung für den Flammenstab eines Flammenwächters
EP0867661A3 (de) * 1997-03-27 2000-05-24 Honeywell B.V. Flammenwächter mit Flammenstab
DE10202910C1 (de) * 2002-01-25 2003-10-16 Honeywell Bv Schaltungsanordnung zur Ermittlung des Flammenstromes eines Brenners
CN113452328A (zh) * 2021-06-30 2021-09-28 黄俊融 一种信号放大模块及火焰检测电路

Also Published As

Publication number Publication date
EP0498619A3 (en) 1993-05-19
GB2252436A (en) 1992-08-05
GB9102372D0 (en) 1991-03-20

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