WO2012022377A1 - Circuit d'entrée de mesure d'un appareil de mesure ou de protection - Google Patents

Circuit d'entrée de mesure d'un appareil de mesure ou de protection Download PDF

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Publication number
WO2012022377A1
WO2012022377A1 PCT/EP2010/062023 EP2010062023W WO2012022377A1 WO 2012022377 A1 WO2012022377 A1 WO 2012022377A1 EP 2010062023 W EP2010062023 W EP 2010062023W WO 2012022377 A1 WO2012022377 A1 WO 2012022377A1
Authority
WO
WIPO (PCT)
Prior art keywords
feedback
input circuit
feedback branch
current
operational amplifier
Prior art date
Application number
PCT/EP2010/062023
Other languages
German (de)
English (en)
Inventor
Carsten Braun
Harald Strohmaier
Original Assignee
Siemens Aktiengesellschaft
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 Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Priority to PCT/EP2010/062023 priority Critical patent/WO2012022377A1/fr
Publication of WO2012022377A1 publication Critical patent/WO2012022377A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/08—Circuits for altering the measuring range
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means

Definitions

  • the invention relates to a measuring input circuit of a measuring or protective device with a current transformer, which can be acted on the input side with a primary current to be measured, which causes a proportional secondary current at the output of the current transformer, and a related to the output of the current transformer in connection first load resistor to which in the case of a secondary current flowing over a first burden ⁇ voltage can be tapped.
  • the currents to be measured are usually reduced by means provided in the respective devices measured value detection means to the electronic further processing suitable levels.
  • a measuring ⁇ value detection device in this case has a measurement input ⁇ circuit, with a potential separation and a signal adjustment to be made. The adjusted by the measuring circuit input signal levels of the currents to be measured are then converted by an analog / digital converter in ent ⁇ speaking digital samples, which are then fed to the actual further processing and evaluation.
  • the currents detected by a protective device are examined in the course of further processing using so-called protection algorithms to determine whether they indicate a permitted or an unauthorized operating state of the monitored energy supply network.
  • an unauthorized operating state eg, a short circuit on a line
  • the apparatus automatic countermeasures such as opening of a circuit breaker, Weglei ⁇ tet.
  • the current transformer (usually inductive current transformer) ⁇ is introduced, which serve the primary side to detect a to be measured Pri ⁇ märstromes, is caused by the on the secondary side of the power converter ⁇ a reduced level with respect to its secondary Ström.
  • the amount of the secondary current is ei ⁇ neminte of the ratio of the numbers of turns of the windings on the primary side and the secondary side of the current transformer and on the other hand, depending on a load resistor, whose output is connected to the current transformer and through which the secondary current flows.
  • the load resistance as so-called "passive load” directly Zvi ⁇ rule is connected in the outputs of the current transformer.
  • a primary current Ii flowing on the primary side IIa of a current transformer 10 is transformed into a lower secondary current I 2 emitted on the secondary side IIb of the current transformer 10, which in turn is transformed by the output signal at the output side Current transformer 10 is provided ⁇ nen load resistor 12 is converted into a proportional to the secondary current I 2 ⁇ burden voltage U 2 .
  • ni and n 2 the number of turns of the windings on the primary side IIa and on the secondary side IIb are designated in FIG.
  • the invention has for its object to provide a measuring input ⁇ circuit of the type mentioned above, which can cover a larger measuring range in particular when using cost-effective current transformers with little core material.
  • This object is achieved in that is connected to the output of the current transformer, an operational amplifier, which is provided with a first fed back to the inverting input of the operational amplifier feedback ⁇ branch, which is connected in such a way that the operational amplifier tion amplification of the first burden resistor applied to the first load voltage of about -1 (minus 1), and which is provided with a second feedback path fed back to the inverting input of the operational amplifier, which is connected to a first feedback load resistor.
  • a ⁇ ers th switching device is provided which is adapted to either the first or the second feedback branch mono- switch on and lock the respective other feedback branch.
  • An advantage of the measurement input circuit according to the invention is given by the fact that it has two modes of operation by the switchable burden resistors. While in one ers ⁇ th mode large currents can be measured in a comparatively large range with the first load resistance, is of suitable in the second feedback branch of the Opera- tion amplifier provided feedback load resistor in a second mode for measuring lower currents in a small measuring range, since the virtual load resistance caused by the operational amplifier is nearly 0 ohms in this case. Moreover, the use of a switchable binding of the current transformer makes it unnecessary to use an operational amplifier for high powers, so that no unnecessarily high costs are associated with the measuring input circuit according to the invention. An advantageous embodiment of the measurement input circuit according to the invention provides that the first load resistor is smaller than the first feedback load resistor.
  • the measuring ranges of the switchable operating modes can be adapted such that high primary currents can be measured when the first feedback branch is switched on (use of the first load resistor), while low primary currents are measured when the second feedback branch is switched on (use of the first feedback load resistor) can be.
  • a further advantageous embodiment of the invention shown SEN measurement input circuit further provides that the operational amplifier is wired while the first feedback branch as an inverter, and when the second feedback branch as an inverting current to voltage converter.
  • the position of the first switching device is determined by a parameterization provided in the measuring or protective device.
  • the user of such a measurement or protection device can determine the operating mode of the gearshift through a Messein ⁇ rätes within the parameterization of the overall fixed setting.
  • a particular advantage of such a parameter-controlled definition of the operating mode is the fact that a change of the operating mode in a simple manner, namely by a corresponding changed setting of the corresponding parameter is possible without having to make changes to the egg ⁇ tual input circuit.
  • Position of the first switching device is set dynamically depending on the primary current.
  • the setting of the operating mode of the measuring input circuit is quasi-tracked to the current level of the primary current, so that the respective covered by the measuring input circuit measuring range is adjusted in each case the height of the primary current.
  • the tracking can be realized by simple measuring devices on the primary or secondary side of the current transformer, the need to make any exact Bestim ⁇ mung of the current, but only need to specify the region (for example, by multistage
  • Threshold value transmitter in which the primary or secondary Ström is currently located, so that a corresponding control of the first switching device can be made.
  • the first switching device is set up in such a way that it switches on the first feedback branch with a high primary current and switches on the second feedback branch with a low primary current.
  • a further advantageous embodiment of the invention shown SEN measurement input circuit is provided in that a further load resistance at the output of the current transformer in addition to the first load resistance provided at least, and a second switching means is provided for the switchover between the first and the at least one further Burden resistance is set up.
  • Switching device can also be done either parameter-controlled or depending on the primary current to be measured.
  • the first and the at least one further burden resistor are arranged as a voltage divider.
  • the measurement input circuit in addition to the first and the second feedback branch at least one further fed back to the inverting input of the operational amplifier feedback path is provided, which is connected in each case with a further feedback burden resistor, and the first Druckeinrich - Direction is adapted to switch ⁇ either the first remindp ⁇ ment branch or one of the other feedback branches ⁇ .
  • the appropriate control of the first switching means may again either parameter-controlled or a function of the measured Pri ⁇ märstromes.
  • Figure 1 is an exemplary diagram of a measuring ⁇ input circuit according to the prior art
  • Figure 2 shows a first embodiment of a
  • Figure 3 shows a second embodiment of a
  • FIG. 2 shows a first embodiment of a Messein ⁇ gears 20.
  • the measurement input circuit 20 comprises a current transformer 21 on the primary side of a to be measured primary current Ii flows which induces on the secondary side of the current wall ⁇ coupler 21 a secondary current I2.
  • a first load resistor 22 is connected to the current transformer 21 with the value R2.
  • an operational amplifier 23 is provided at the output of the current transformer 21, with its inverting terminal (-) via a resistor 26 with the value R with a terminal of the current transformer 21 in contact and with its non-inverting terminal (+) with the other terminal of the current transformer 21 is connected.
  • two feedback paths are provided, which each produce a feedback of the output of the operational amplifier to its invertie ⁇ in power input, namely a first feedback branch 24, which has a resistor 27, and a second feedback branch 25, which comprises a feedback burden resistor 28 with the value R3.
  • a first feedback branch 24 which has a resistor 27, and a second feedback branch 25, which comprises a feedback burden resistor 28 with the value R3.
  • Switching device 29 is provided which is set up such that it either the first feedback branch 24 turns on ⁇ and simultaneously blocks the second feedback branch 25 or the first feedback branch 24 blocks and simultaneously turns on the second feedback branch 25.
  • the measurement ⁇ voltage U3 can be tapped at the output of the operational amplifier, which is a measure of the primary current Ii.
  • umschaltba- ren feedback branches 24 and 25 are for the Messein ⁇ shifter 20 two different modes of operation reali ⁇ Siert whose measurement areas by the value of the resistors 22, 26, set 27 and 28th In the first mode the first Druckeinrich ⁇ tung 29 switches the first feedback branch 24 and blocks the second feedback branch 25. Thereby, the first Bür ⁇ the resistor 22 determining the value R 2 of the value of the output side can be tapped measurement voltage U3.
  • the secondary current I 2 on the first load resistor 22 into a proportional first clamping load ⁇ voltage U 2, - is applied via the resistor 26 at the Operati ⁇ onsverschreibr 23rd Since the first switching device 29 has turned on the first feedback branch 24 and the values R of the resistors 26 and 27 coincide, the operational amplifier 23 is operated in this case as an inverting operational amplifier with a gain of -1.
  • the following relationship applies to the value of the measuring voltage U3 in the first operating mode:
  • Burden resistance 28 determining the value of the measuring voltage u 3 .
  • the operational amplifier in this second mode of operation, is connected as a current-to-voltage converter and converts the secondary current I 2 into the measurement voltage U 3 proportional thereto.
  • the measurement voltage U 3 drives the output of the Opera ⁇ tion amplifier 23 via the second feedback branch 25 a compensating current through the feedback load resistance 28 corresponding to the negative value of the Sekundärstro ⁇ I mes. 2
  • the current transformer 21 in the second mode sees a burden of nearly 0 ohms.
  • the value R 2 of the first load resistor 22 is selected to be smaller than the value R 3 of the feedback load resistor 28, a measurement of high secondary currents I 2 in a large measurement range can be achieved in the first operating mode (switched on feedback branch 24). while at the second mode (feedback path 25 is turned on) ei ⁇ ne measurement of low secondary currents I2 is possible in a small measuring range.
  • the position of the first switching device 29 can be determined, for example, by parameterizing the measuring or protective device comprising the measuring input circuit.
  • ⁇ at a setting value may be set to a entspre ⁇ sponding value specifying the position of the switching device 29th
  • the position of the first switching device can also be dynamically adapted to the height of the measured primary current Ii that, in dependence of the primary current Ii (or proportional thereto, the secondary current I 2) with simp ⁇ chen threshold value switches on the range limits of the measuring ranges of the first and second operating mode are set, a drive signal for the switching device 29 is generated.
  • a drive signal is generated which causes the first switching means for a ⁇ switching the first feedback path 24, and (at a low primary current Ii or secondary current I 2 ), a drive signal is generated, which causes the first switching device for switching on the second feedback branch 24.
  • FIG. 3 shows a second embodiment of a Messein ⁇ gears 30.
  • the basic function of the measured input circuit 30 agrees with that of the measurement input circuit 20 (see Figure 2), so that on the one hand corresponding components are denoted by the same reference numerals, and on the other hand covers only different features in the De ⁇ tail with respect to the description of FIG. 3
  • a further load resistor 31 with the value R4 vorgese ⁇ hen in addition to the first load resistor 22, a further load resistor 31 with the value R4 vorgese ⁇ hen.
  • the two load resistors 22 and 31 are arranged in the form ei ⁇ nes voltage divider.
  • a second Druckeinrich ⁇ device 32 allows switching between the complete value of the voltage divider or a corresponding partial amount of its resistance.
  • two additional feedback branches 33 and 34 are provided to extend the operating mode scope to ⁇ addition to the first and the second feedback branch 24 and 25, each having their own feedback load resistors 35 (with the value R5) and 36 (with the value Re).
  • the first switching device 29 is correspondingly extended to the added feedback branches 33 and 34 and clearedstal ⁇ tet that it either the first feedback branch 24 (to realize the two sub-modes of the first mode) or one of the other three feedback branches 25, 33 or 34 turns on, whereby - depending on the switched feedback path 25, 33 or 34 - and the second operating ⁇ type is divided into three sub-modes quasi.
  • the measuring ranges of the measuring equipment can be given an appropriate choice of the values of R 2, R3, 4, R5 and R6 are the reflection ⁇ stands 22, 28, 31, very carefully set the starting circuit 30. As explained with reference to FIG. 2, this can also be done either by a corresponding parameterization of the measuring or protective device or by a dynamic adaptation to the current value of the primary current (or of the secondary current proportional thereto).
  • both more and less than five operating modes (or sub-modes) of the measuring input circuit can be realized.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Measurement Of Current Or Voltage (AREA)

Abstract

L'invention concerne un circuit d'entrée de mesure (20, 30) d'un appareil de mesure ou de protection comportant un transformateur de courant (21) qui peut être alimenté du côté de l'entrée avec un courant primaire à mesurer qui produit à la sortie du transformateur de courant (21) un courant secondaire proportionnel, et une première résistance de charge (22) connectée à la sortie du transformateur de courant (21) à laquelle une première tension de charge peut être prélevée en cas de circulation d'un courant secondaire. Pour améliorer un tel circuit d'entrée de mesure de telle sorte que - sans coût additionnel important - il puisse couvrir une plus grande plage de mesure, l'amplificateur opérationnel (23) selon l'invention comporte une première branche de réaction (24) reconduite à l'entrée inverseuse de l'amplificateur opérationnel qui est raccordée de telle sorte que l'amplificateur opérationnel (23) produise une amplification de la première tension de charge d'environ -1 aux bornes de la première résistance de charge (22), et est connecté à la sortie du transformateur de courant (21) ; l'amplificateur opérationnel comporte aussi une deuxième branche de réaction (25) reconduite à l'entrée inverseuse de l'amplificateur opérationnel (23) qui est raccordée à une première résistance de charge de réaction (28) ; et un dispositif de commutation (29) sert à activer soit la première (24) soit la deuxième branche de réaction (25) et à bloquer l'autre branche de réaction respective.
PCT/EP2010/062023 2010-08-18 2010-08-18 Circuit d'entrée de mesure d'un appareil de mesure ou de protection WO2012022377A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2010/062023 WO2012022377A1 (fr) 2010-08-18 2010-08-18 Circuit d'entrée de mesure d'un appareil de mesure ou de protection

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2010/062023 WO2012022377A1 (fr) 2010-08-18 2010-08-18 Circuit d'entrée de mesure d'un appareil de mesure ou de protection

Publications (1)

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WO2012022377A1 true WO2012022377A1 (fr) 2012-02-23

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102017221173A1 (de) 2017-11-27 2019-05-29 Siemens Aktiengesellschaft Strommessvorrichtung

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2339856A1 (de) * 1973-08-07 1975-02-13 Teldix Gmbh Strommesseinrichtung
US4032836A (en) * 1975-11-28 1977-06-28 The Gillette Company Transformer circuit
EP0724161A2 (fr) * 1995-01-27 1996-07-31 Eaton Corporation Appareil électrique avec une large gomme dynamique pour surveillance et protection d'un système de distribution d'énergie électrique
GB2388914A (en) * 2002-05-10 2003-11-26 Pri Ltd Current transformer with reduced resistance
EP1970716A2 (fr) * 2007-02-12 2008-09-17 Rockwell Automation Technologies, Inc. Procédé et système de détection de courant à plage étendue

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2339856A1 (de) * 1973-08-07 1975-02-13 Teldix Gmbh Strommesseinrichtung
US4032836A (en) * 1975-11-28 1977-06-28 The Gillette Company Transformer circuit
EP0724161A2 (fr) * 1995-01-27 1996-07-31 Eaton Corporation Appareil électrique avec une large gomme dynamique pour surveillance et protection d'un système de distribution d'énergie électrique
GB2388914A (en) * 2002-05-10 2003-11-26 Pri Ltd Current transformer with reduced resistance
EP1970716A2 (fr) * 2007-02-12 2008-09-17 Rockwell Automation Technologies, Inc. Procédé et système de détection de courant à plage étendue

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
TIETZE U., SCHENK C.: "Halbleiter-Schaltungstechnik", 1 January 1999, SPRINGER, Berlin, ISBN: 3-540-64192-0, pages: 815 - 817, XP002639567 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102017221173A1 (de) 2017-11-27 2019-05-29 Siemens Aktiengesellschaft Strommessvorrichtung

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