WO2008065112A1 - Détecteur inductif de conductivité - Google Patents

Détecteur inductif de conductivité Download PDF

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Publication number
WO2008065112A1
WO2008065112A1 PCT/EP2007/062887 EP2007062887W WO2008065112A1 WO 2008065112 A1 WO2008065112 A1 WO 2008065112A1 EP 2007062887 W EP2007062887 W EP 2007062887W WO 2008065112 A1 WO2008065112 A1 WO 2008065112A1
Authority
WO
WIPO (PCT)
Prior art keywords
coil
turns
conductivity sensor
transmitting coil
receiving
Prior art date
Application number
PCT/EP2007/062887
Other languages
German (de)
English (en)
Inventor
Andreas Eberheim
Torsten Pechstein
Original Assignee
Endress+Hauser Conducta Gesellschaft Für Mess- Und Regeltechnik Mbh+Co. Kg
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 Endress+Hauser Conducta Gesellschaft Für Mess- Und Regeltechnik Mbh+Co. Kg filed Critical Endress+Hauser Conducta Gesellschaft Für Mess- Und Regeltechnik Mbh+Co. Kg
Publication of WO2008065112A1 publication Critical patent/WO2008065112A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/023—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance where the material is placed in the field of a coil

Definitions

  • the present invention relates to an inductive conductivity sensor for determining the conductivity of a liquid medium.
  • Inductive conductivity sensors essentially comprise one
  • Double transformer with a mostly annular transmitting coil and a generally annular receiving coil, a Kurz practitionerpfad with the medium to be measured, which passes through the transmitting coil and the receiving coil, a transmitting coil electrically connected to the transmitting means for supplying the coil with an AC voltage and electrically connected to the receiving coil receiving device.
  • Such conductivity sensors are for example in the
  • Inductive conductivity sensors have a typical measuring range of about 20 ⁇ S / cm to 2 S / cm.
  • the measuring range at low conductivities is limited by the fact that the signals of the receiving coil are very small and are superimposed by the residual coupling signal (output signal without medium).
  • the residual coupling signal is in particular composed of a capacitive coupling of the leads and an inductive coupling of the coils.
  • the output signal can be amplified by a higher input voltage, the higher input voltage is also associated with a larger capacitive coupling and a larger transmit coil current with a larger inductive coupling.
  • the present invention is therefore based on the object to provide a conductivity sensor, which overcomes the disadvantages of the prior art.
  • the object is achieved by the conductivity sensor according to the independent claim 1.
  • the conductivity sensor according to the invention for detecting the conductivity of a liquid medium comprises a double transformer, with a preferably annular transmitting coil and a preferably annular receiving coil, a short-circuit path formed in the measuring operation by the medium to be measured, which passes through the transmitting coil and the receiving coil, a transmitting coil electrically connected to the transmitting means for feeding the transmitting coil with an AC voltage, and one electrically connected to the receiving coil Receiving device, wherein the transmitting coil and / or the receiving coil have or have a switchable number of turns.
  • the number of turns refers to the respective connected turns of the coils, which are traversed by the excited in the transmitting device or by the detected in the receiving device current.
  • the receiving coil has a switchable number of turns, whereby the turns ratio between the transmitting coil and the receiving coil, for example, from about 1: 1 to not less than about 2: 1, preferably not less than about 3: 1, and, more preferably, not less than about 4: 1 switchable to detect the conductivity of low conductivity media.
  • the number of turns of the transmitting coil for example, 20 to 250
  • Windings amount In a presently preferred embodiment, the number of turns of the primary coil is about 120 turns.
  • the number of turns of the receiving coil arise in accordance with the above conditions.
  • Switching between the various numbers of turns is preferably carried out depending on the measuring range via an electronic switch by switching between appropriately provided Spulenabgriffen, which are assigned to the number of turns.
  • each Spulenabgriff initially an I-U converter are supplied, wherein the selection of the voltage signal to be exploited by an electronic switch, which is arranged downstream of the I-U converters.
  • the receiving device can for this purpose according to a Embodiment of the invention comprise a control circuit which controls the electronic switch measuring range dependent.
  • Reception coil between more than two values in particular three values for the number of turns can be switched.
  • the turns of the two coils are annular or annular section-shaped, wherein the turns each extend around an annular magnetic core.
  • the turns can actually be created by winding a continuous wire, or by connecting individual conductor sections on printed circuit boards with plated-through holes, as disclosed in the still unpublished patent application no. 102006025194.
  • annular refers to a coil with a self-contained magnetic path, so if a magnetic core is provided, it must be self-contained, the shape of the ring does not matter, a circular ring is the simplest However, any other shapes are conceivable, in particular ellipses, rectangles or other polygons
  • the turns do not have to be distributed homogeneously over the magnetic core They can be distributed with different number of windings over the annular magnetic core and in particular limited to a section of the magnetic core.
  • the transmitting device can advantageously be operated at a substantially constant transmission frequency, which corresponds for example to the resonant frequency of the transmitting coil in the measuring circuit.
  • the transmitter may include frequency control to adjust the exciter frequency to the actual resonant frequency.
  • the transmission frequency may generally be between about 100 Hz and 40 kHz, preferably between 500 Hz and 20 kHz and more preferably 1 kHz to 10 kHz.
  • the number of turns of the transmitting coil is made switchable, it is currently preferred to adapt the transmission frequency of the transmitting device to the winding speed-dependent resonant frequency of the transmitting coil.
  • Fig. 1 a schematic representation of a conductivity sensor according to the invention.
  • the inductive conductivity sensor shown in Fig. 1 comprises a transmitting coil 2 with 120 turns, which are wound around a first annular ferrite core 3.
  • the transmitting coil 3 is excited by a transmitting device 4 with an alternating voltage of a frequency which corresponds approximately to the resonant frequency of the transmitting coil in the transmitting device.
  • Coaxial with the transmitting coil 2 is a receiving coil 5 with a
  • Total wind number of 120 turns also arranged, which are wound around a second annular magnetic core 6.
  • the induced current in the receiving coil can be evaluated by a receiving circuit 7.
  • the openings of the annular coil cores are penetrated by the medium to be examined, which forms a short-circuit path 8.
  • the resistance R Med ⁇ um of the medium can be determined according to where l receive the induced current in the receiver coil, U transmit the excitation voltage at the transmitter coil, N transmit the number of current-carrying turns of the transmitter coil, and N receive the number of current-carrying turns of the receiver coil. Accordingly, for a given media resistance:
  • the receiving coil 5 comprises an initial tap 10 and an end tap 11, between which all 120 turns of the receiving coil 5 extend.
  • the coil further comprises an intermediate tap 12 after 30 turns.
  • the control of the switch 14, for example, automatically carried out in dependence of the measured induced current from the receiving device 14.

Abstract

L'invention concerne un détecteur inductif de conductivité (1) qui comprend un double transformateur doté d'une bobine émettrice (2), d'un parcours du court-circuit (8) et d'une bobine de réception (5). Le parcours du court-circuit (8) formé en fonctionnement de mesure traverse le fluide à mesurer, la bobine émettrice (2) et la bobine de réception (5); un dispositif émetteur (4) est relié électriquement à la bobine émettrice (2) pour alimenter la bobine émettrice en une tension alternative et un dispositif de réception (7) est relié électriquement à la bobine de réception (5), la bobine émettrice (2) et/ou la bobine de réception (5) présentant en outre un nombre commutable d'enroulements.
PCT/EP2007/062887 2006-11-27 2007-11-27 Détecteur inductif de conductivité WO2008065112A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE200610056174 DE102006056174A1 (de) 2006-11-27 2006-11-27 Induktiver Leitfähigkeitssensor
DE102006056174.0 2006-11-27

Publications (1)

Publication Number Publication Date
WO2008065112A1 true WO2008065112A1 (fr) 2008-06-05

Family

ID=39092928

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2007/062887 WO2008065112A1 (fr) 2006-11-27 2007-11-27 Détecteur inductif de conductivité

Country Status (2)

Country Link
DE (1) DE102006056174A1 (fr)
WO (1) WO2008065112A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114034929A (zh) * 2021-11-12 2022-02-11 国家海洋技术中心 非外部场感应式电导率传感器

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008047960A1 (de) 2008-09-18 2010-03-25 Endress + Hauser Conducta Gesellschaft für Mess- und Regeltechnik mbH + Co. KG Ringspule
DE102008048996A1 (de) 2008-09-25 2010-04-01 Endress + Hauser Conducta Gesellschaft für Mess- und Regeltechnik mbH + Co. KG Induktiver Leitfähigkeitssensor
DE102008048995A1 (de) 2008-09-25 2010-04-01 Endress + Hauser Conducta Gesellschaft für Mess- und Regeltechnik mbH + Co. KG Induktiver Leitfähigkeitssensor
DE102012112388A1 (de) 2012-12-17 2014-07-03 Endress + Hauser Conducta Gesellschaft für Mess- und Regeltechnik mbH + Co. KG Induktiver Leitfähigkeitssensor und Verfahren zu dessen Herstellung
DE102016119508A1 (de) 2016-10-13 2018-04-19 Krohne Messtechnik Gmbh Leitfähigkeitssensor und Verfahren zur Bestimmung der elektrischen Leitfähigkeit eines flüssigen Mediums

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4000458A (en) * 1975-08-21 1976-12-28 Bell Telephone Laboratories, Incorporated Method for the noncontacting measurement of the electrical conductivity of a lamella
EP0192915A1 (fr) * 1985-02-27 1986-09-03 I.M.E.C. S.p.A. Transformateur avec rapport de transformation variable pendant le fonctionnement
EP0999441A1 (fr) * 1998-11-06 2000-05-10 Endress + Hauser Conducta Gesellschaft für Mess- und Regeltechnik mbH + Co. Capteur de conductibilité électrique de liquide
US6320764B1 (en) * 2000-03-31 2001-11-20 Yimin Jiang Regulation circuit for a power converter and method of operation thereof

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1598074A1 (de) * 1965-09-25 1970-07-09 Bissett Berman Corp Messsystem
DE4116468A1 (de) * 1991-05-21 1992-11-26 Knick Elekt Messgeraete Gmbh Induktive leitfaehigkeits-messzelle
US6414493B1 (en) * 2001-03-26 2002-07-02 Rosemount Analytical Inc. Toroid conductivity sensor
DE10334830A1 (de) * 2003-07-30 2005-05-19 Siemens Ag Spule mit einem magnetischen Kern integriert in eine Leiterplatte

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4000458A (en) * 1975-08-21 1976-12-28 Bell Telephone Laboratories, Incorporated Method for the noncontacting measurement of the electrical conductivity of a lamella
EP0192915A1 (fr) * 1985-02-27 1986-09-03 I.M.E.C. S.p.A. Transformateur avec rapport de transformation variable pendant le fonctionnement
EP0999441A1 (fr) * 1998-11-06 2000-05-10 Endress + Hauser Conducta Gesellschaft für Mess- und Regeltechnik mbH + Co. Capteur de conductibilité électrique de liquide
US6320764B1 (en) * 2000-03-31 2001-11-20 Yimin Jiang Regulation circuit for a power converter and method of operation thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
K. STRIGGOW AND R. DANKERT: "The Exact Theory of Inductive Conductivity Sensors for Oceanografic Application", IEEE JOURNAL OF OCEANIC ENGINEERING, vol. 10, no. 2, April 1985 (1985-04-01), pages 175 - 179, XP002470775 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114034929A (zh) * 2021-11-12 2022-02-11 国家海洋技术中心 非外部场感应式电导率传感器
CN114034929B (zh) * 2021-11-12 2024-04-19 国家海洋技术中心 非外部场感应式电导率传感器

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