EP3916128A1 - Circuit de protection cathodique contre la corrosion et agencement de mesure lors de la protection cathodique contre la corrosion - Google Patents

Circuit de protection cathodique contre la corrosion et agencement de mesure lors de la protection cathodique contre la corrosion Download PDF

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Publication number
EP3916128A1
EP3916128A1 EP20176896.7A EP20176896A EP3916128A1 EP 3916128 A1 EP3916128 A1 EP 3916128A1 EP 20176896 A EP20176896 A EP 20176896A EP 3916128 A1 EP3916128 A1 EP 3916128A1
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EP
European Patent Office
Prior art keywords
measuring
voltage
input
circuit arrangement
output
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.)
Pending
Application number
EP20176896.7A
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German (de)
English (en)
Inventor
Kevin Schick
Lukas HENKEL
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Icor Intelligent Corrosion Control GmbH
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Icor Intelligent Corrosion Control GmbH
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Priority to EP20176896.7A priority Critical patent/EP3916128A1/fr
Publication of EP3916128A1 publication Critical patent/EP3916128A1/fr
Pending legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
    • C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
    • C23F13/04—Controlling or regulating desired parameters
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F2201/00—Type of materials to be protected by cathodic protection
    • C23F2201/02—Concrete, e.g. reinforced

Definitions

  • the invention relates to a circuit arrangement for cathodic corrosion protection (KKS) of reinforcement in concrete with a voltage source or current source and a supply voltage provided between a positive pole and a negative pole of the voltage source or current source.
  • the circuit arrangement has a closed current path with a cathode and an anode, the negative pole of the voltage source or current source being connected to the reinforcement as a cathode and the positive pole of the voltage source or current source being connected to an anode that is electrically conductive in the concrete.
  • the corrosion protection When the corrosion protection is in operation, an electric field is created between the cathode (reinforcement) and the anode. All positively charged ions migrate towards the reinforcement and all negatively charged ions migrate away from the reinforcement towards the anode. This leads to a 'desalination' in the vicinity of the reinforcement over time. This can reduce the risk of corrosion of the reinforcement.
  • the cathodic protection leads to an increase in the alkalinity near the reinforcement, which increases a critical, corrosion-inducing chloride content and thus improves the corrosion protection of the reinforcement.
  • a linear regulator with an input and an output is provided as a voltage source or current source for cathodic corrosion protection.
  • the output of the linear regulator provides the supply voltage, while an input voltage is applied to the input of the linear regulator.
  • a linear regulator has a poor degree of efficiency due to its design and heats up considerably due to its power dissipation.
  • the power loss of a linear regulator is shown in simplified form as a function of the difference between its input voltage and its output voltage.
  • a linear regulator provides a highly accurate output voltage with only low residual ripple, which is particularly advantageous when used in measuring devices and for measuring very small measured variables.
  • a minimum voltage difference between the input voltage and the output voltage is absolutely necessary for the operation of a linear regulator.
  • the invention is based on the object of specifying a circuit arrangement for cathodic corrosion protection of reinforcement in concrete which enables the supply voltage necessary for operating the corrosion protection to be provided with low losses.
  • the circuit arrangement comprises a linear regulator with an input and an output which, as a voltage source or current source, provides the supply voltage or the protective current, in particular a constant current for cathodic corrosion protection.
  • the input voltage of the linear regulator is provided by the output voltage of a DC / DC converter.
  • the DC / DC converter is an adjustable DC / DC converter whose output voltage is set by a DC / DC control unit as a function of a control value.
  • the voltage drop is recorded via the linear regulator. To do this, the at the entrance of the linear regulator and the voltage delivered at the output of the linear regulator are compared and the voltage drop is determined. This voltage drop of the linear regulator is used as a control variable to control the output voltage of the DC / DC converter. The controlled variable is fed directly or indirectly as a manipulated variable to the control unit of the DC / DC converter.
  • a precise voltage drop across the linear regulator can be set via the control loop of the DC / DC converter by setting its output voltage depending on the voltage drop on the linear regulator.
  • a setpoint value of the voltage drop is determined by a digital control unit of the assembly and made available by a digital-to-analog converter of the circuit arrangement. This makes it possible to use intelligent algorithms in software in the digital control unit which influence the setpoint value of the voltage drop across the linear regulator, in particular as a function of the output load of the linear regulator.
  • a high quality of the supply voltage is provided by the linear regulator and, at the same time, a high efficiency of the overall system is achieved through the dynamic tracking of the upstream DC / DC converter.
  • the circuit arrangement according to the invention ensures the provision of an output voltage with a very high absolute accuracy.
  • DC / DC converter DC voltage converter
  • linear regulator Compared to protective current devices used previously in cathodic corrosion protection (KKS), the inventive combination of DC / DC converter (DC voltage converter) and linear regulator enables a very wide setting range with very high absolute accuracy. There is therefore no need to make an unfavorable compromise between output power and accuracy.
  • control unit can set the controllable DC / DC converter in such a way that the via the linear regulator dropping voltage is minimal. In this way, the power loss of the linear regulator can be minimized.
  • a difference generator is provided which is designed to form a difference value between the measured voltage drop as the actual value and a predetermined voltage drop as the target value.
  • the difference value is fed as a difference signal to a control unit for controlling the DC / DC converter.
  • the SET value of the specified voltage drop is expediently provided as an analog value.
  • the specified voltage drop is calculated as the setpoint value by a higher-order digital control unit, preferably with software, and is supplied to the difference calculator as an analog value via a digital / analog converter.
  • the output signal of the control unit in particular designed as a PID controller, and the output voltage of the DC / DC converter are fed to a difference calculator.
  • the difference calculator is designed to form a difference value between the output signal of the control unit and the output voltage of the DC / DC converter. This difference value is fed as a difference signal to the DC / DC control unit for controlling the DC / DC converter.
  • a separating device is interposed between the output of the linear regulator and the power output of the circuit arrangement.
  • the isolating device is designed to isolate the electrical connection between the output of the linear regulator and the power output of the circuit arrangement in response to a received error signal from a control unit.
  • the control unit is connected to an error monitoring unit.
  • the control unit is designed to receive, store and evaluate comparison signals from the error monitoring unit and to generate an error signal as a function of evaluation criteria and / or evaluation algorithms.
  • the error signal is received by the isolating device and, in response to the error signal, the electrical connection between the output of the linear regulator and the power output of the circuit arrangement is disconnected.
  • the separating device is formed exclusively from semiconductor components in solid state construction.
  • the electrical isolation of the load is advantageously implemented by two power field effect transistors (MOSFET), which ensures a very high switch-off resistance and a very fast response time.
  • MOSFET power field effect transistors
  • a measuring arrangement in the form of a circuit arrangement for measuring electrical quantities during cathodic corrosion protection of reinforcement in concrete which consists of a first measuring input connected to an anode and a second measuring input connected to a cathode and one between the first measuring input and the second measuring input arranged measuring resistor.
  • the voltage drop across the measuring resistor is recorded and fed to an evaluation unit.
  • the circuit arrangement is designed such that a first switch is arranged between the first measuring input connected to the anode and the measuring resistor and a second switch is arranged between the second measuring input connected to the cathode and the measuring resistor.
  • the measuring resistor is connected on the anode side via a third switch to a reference voltage source and on the cathode side connected to ground or the zero potential of the protective circuit via a fourth switch.
  • the arrangement is like this made that the measuring resistor is to be conductively connected with its first connection via the first switch to the first measurement input or via the third switch to the reference voltage source.
  • the measuring resistor can be conductively connected with its second connection via the second switch to the second measurement input or via the fourth switch to ground.
  • This measuring arrangement (circuit arrangement) is used to determine the voltage directly at the load (reinforcement in concrete) during operation of the cathodic corrosion protection (KKS) in order to subsequently adapt the supply voltage or a protective current via the higher-level digital control unit.
  • the measurement in the measuring arrangement takes place differentially, which on the one hand guarantees increased interference immunity and on the other hand enables high accuracy.
  • the very high input resistance of the measuring arrangement ensures that the voltages and currents to be measured on the load during operation do not influence the load itself.
  • the connected test leads also have no effect on the load itself.
  • a first ohmic resistor is connected between the first switch and the first measuring input on the anode side.
  • a second ohmic resistor is connected between the second switch and the second measuring input on the cathode side.
  • One connection of a third ohmic resistor is directly connected to the cathode-side, second measurement input via a fifth switch, and its other connection is connected to the anode-side connection of the measurement resistor.
  • the arranged resistors can also be referred to as “equalization resistors” and are used to calibrate and check the measuring arrangement and / or the measuring lines.
  • the first ohmic resistance, the second ohmic resistance and the third ohmic resistance preferably have the same value.
  • the switches provided in the measuring arrangement are semiconductor components and are controlled by a higher-level digital control unit.
  • the higher-level digital control unit carries out compensation processes such as a gain correction measurement, an offset measurement, an equalization measurement and / or a connection check of the connected measuring lines.
  • the measuring resistor arranged in the measuring arrangement is preferably part of a voltage divider.
  • the first measuring input is connected to the anode-side connection of the measuring resistor via a first operational amplifier and the first switch in series
  • the second measuring input is connected to the cathode-side connection of the measuring resistor via a second operational amplifier and the second switch located in series.
  • the operational amplifiers are negative feedback operational amplifiers that work as voltage followers.
  • the input voltage of the operational amplifier and its output voltage are the same.
  • the current through the operational amplifier is amplified.
  • a basic structure of a protective arrangement 60 for active corrosion protection of a reinforcement 4 in concrete 2 is shown schematically.
  • a reinforcement 4 is shown, which can be present in the form of reinforcing bars, reinforcement mats, reinforcement cages or the like.
  • the reinforcement 4 forms a cathode 12 in a current path 10, which leads through the concrete 2 to an anode 6 that is conductively integrated in the concrete and back to the cathode 12 via the negative pole 5 and the positive pole 3 of a voltage source 7.
  • a current source can also be provided.
  • the invention is described below using a voltage source.
  • the voltage source or current source can generally also be referred to as an electrical energy source.
  • Fig. 2 the schematic structure of a circuit arrangement 1 with the voltage source 7 mentioned as an example for providing a supply voltage U mess for the protective arrangement 60 is shown.
  • the arrangement for active corrosion protection of a reinforcement 4 in concrete 2 is also provided with a measuring device 8 which can be parallel to the voltage source 7 and which detects the voltage on the load.
  • the measuring device 8 is connected to the reinforcement 4 as a cathode 12 and to the anode 6 which is embedded in the concrete in a conductive manner.
  • a circuit arrangement 100 or measuring arrangement of the measuring device 8 is shown schematically in FIG Figures 3 to 8 reproduced.
  • FIG Fig. 2 The structure of the circuit arrangement 1 of a voltage source 7 is shown in FIG Fig. 2 shown.
  • the supply voltage U mess which is necessary for the operation of the protective arrangement 60 of the cathodic corrosion protection, is present.
  • the power output 40 is fed by a linear regulator 14, the output 18 of which in the illustrated embodiment according to Fig. 2 is preferably connected directly to the power output 40.
  • the output voltage U A of a DC / DC converter 20 is present at the input 16 of the linear regulator 14.
  • the output voltage U A is fed to the input 16 of the linear regulator 14 via a filter 15 for stabilizing and smoothing the output voltage.
  • the linear regulator 14 is controlled by a driver 13, via which the supply voltage U mess provided at the output 18 of the linear regulator 14 is set and, in particular, is kept constant.
  • the supply voltage U mess at the output of the linear regulator 14 is fed to a difference calculator 19, which compares the supply voltage U mess with a preset value which is fed to the difference calculator 19 via a digital / analog converter 17.
  • the preset value is preset in analog form via the digital-to-analog converter 17 and is parameterized by a higher-level digital control unit and preferably a digital controller mapped therein.
  • the dashed in Fig. 2 The illustrated control circuit of the linear regulator 14 changes the resistance of the inner linear element. By varying this resistance accordingly, a desired supply voltage Umess or a desired output current is provided at output 18. Both a supply voltage and an output current can be switched dynamically by the higher-level digital control unit.
  • the linear regulator 14 has a high DC accuracy, a high bandwidth and a low supply voltage penetration. These properties make it possible to provide an output variable with high absolute accuracy and low residual ripple at output 18.
  • the driver 13 of the linear regulator 14 is supplied as an input signal 11 with the difference between the supply voltage U mess at the output 18 of the linear regulator 14 and the default value. Depending on the size of the input signal 11 supplied, the driver 13 controls the linear regulator 14 until, for example, the voltage difference between the supply voltage U mess and the default value has dropped to a minimum, in particular to zero.
  • the control of the linear regulator 14 via the driver 13 is preferably independent of the control of the output voltage U A of the DC / DC converter 20 described below.
  • the control loop of the linear regulator 14 is shown in FIG Fig. 2 shown in dashed lines.
  • the output voltage U A present at the input 16 of the linear regulator 14 and the supply voltage U mess tapped at the output 18 of the linear regulator 14 are fed to a differentiator 21, which determines the voltage drop ⁇ U across the linear regulator 14.
  • the determined voltage drop .DELTA.U is fed to a further difference calculator 22 as an actual value.
  • the further subtractor 22 determines the difference between the value supplied as analog voltage drop .DELTA.U as an actual value and a preset value, in particular a predetermined voltage drop to .DELTA.U as desired value.
  • the difference value is fed as a difference signal 23 to a control unit 24 for controlling the DC / DC converter 20.
  • the default value can be a maximum allowable voltage drop .DELTA.U should be.
  • the maximum permissible voltage drop .DELTA.U should be determined according to predetermined criteria such as loading of the electronic components or the like.
  • the default value can also be determined on the basis of a maximum permissible power loss of the linear regulator 14, for which purpose, in addition to the voltages that occur, the current measured at the power output 40 is also recorded.
  • a default value can be determined as a function of the voltages that occur, the currents that occur and / or the powers that occur.
  • a digital default value determined by the superordinate digital control unit is fed to the further difference former 22 as an analog value via the digital / analog converter 26.
  • the control unit 24 is preferably designed as a PID controller. In this way it can be achieved that the control loop of the linear controller 14 shown in dashed lines to keep its supply voltage U mess constant, does not interfere with the control loop of the controllable DC / DC converter 20 shown in dash-dotted lines, the two control loops are not excited to oscillate or the control loops are negatively influenced in some other way.
  • the output signal 25 of the control unit 24 is fed to a third subtractor 28, to which the output voltage U A of the DC / DC converter 20 is also fed.
  • the difference value formed between the output signal 25 of the control unit 24 and the output voltage U A is fed as an output signal 27 to the control unit 29 of the DC / DC converter 20.
  • the controllable DC / DC converter 20 is supplied with a rectified input voltage U E , which within the DC / DC converter 20 by a periodically operating electronic switch (transistor, power transistor, MOSFET or the like. Semiconductor component) and preferably one or more energy storage in a Output voltage U A is implemented.
  • a clock frequency is fed to the control unit 29 via the line 38.
  • the output voltage U A of the DC / DC converter 20 is set via the control unit 29 as a function of the output signal 27.
  • the control loop of the output voltage U A is in Fig. 2 shown in dash-dotted lines.
  • the regulation of the output voltage U A of the DC / DC converter 20 on the one hand and the regulation of the supply voltage U mess of the linear regulator 14 are fundamentally independent of one another.
  • the regulation of the output voltage U A of the DC / DC converter 20 serves to minimize the power loss occurring via the linear regulator 14.
  • the regulation of the supply voltage U mess is the stabilization of the supply voltage U mess.
  • Fig. 3 shows a schematic representation of a circuit arrangement (measuring arrangement) according to the invention of a measuring channel for the detection of electrical variables during cathodic corrosion protection of reinforcement 4 in concrete 2.
  • the voltages and / or currents occurring between the reinforcement 4 as cathode 12 and an anode 6 are generally used as electrical variables designated.
  • the circuit shown is designed for (remote) detection of the potential directly at the KKS protection zone.
  • the circuit arrangement 100 of the measuring device 8 has a first measuring input A and a second measuring input K.
  • the second measurement input K is connected to the reinforcement 4 as a cathode 12.
  • the second measurement input K can thus also be referred to as the measurement input K on the cathode side.
  • the measurement input A is connected to an anode 6.
  • the anode 6 is an active anode through which a current supplied by the voltage source 7 flows.
  • the first measurement input A can therefore also be referred to as measurement input A on the anode side.
  • a measuring input A or K cannot detect any electrical quantity by itself.
  • the electrical quantity to be recorded results from a combination of one or both measurement inputs A or K.
  • a measuring resistor 45 is located between the first measuring input A on the anode side and the second measuring input K on the cathode side.
  • the measuring resistor 45 is part of a voltage divider 43, which consists of the measuring resistors 44 and 45.
  • the measuring resistors 44 and 45 expediently have the same value. It can be advantageous to design the measuring resistors 44 and 45 with different values.
  • the voltage drop across the measuring resistor 45 is fed to an operational amplifier 46.
  • an operational amplifier 46 In particular, it is an instrumentation amplifier.
  • the resulting advantages are improved common mode suppression and higher DC accuracy. This is achieved by means of resistors integrated in the instrumentation amplifier in contrast to a classic operational amplifier.
  • the especially analog output signal 49 of the operational amplifier 46 is fed to a digital evaluation unit 48 via an analog / digital converter 47.
  • the recorded measured values of the measuring channel are processed via the digital evaluation unit 48 or are supplied to further processing.
  • the first measuring input A on the anode side is connected to one connection 51 of the measuring resistor 45 via a first switch S1.
  • An operational amplifier 34 which advantageously works as a voltage follower, is connected between the switch S1, which is designed in particular using semiconductor technology, and the measuring resistor 45.
  • the negative feedback operational amplifier 34 has the same voltage at the output as at the input, but makes a larger output current available.
  • the second measuring input K on the cathode side is correspondingly connected to the other connection 52 of the measuring resistor 45 via a switch S2, in particular implemented using semiconductor technology, and a counter-coupled operational amplifier 35.
  • a reference voltage source 50 is connected to the branch line 36 between the first switch S1 and the operational amplifier 34 via a third switch S3.
  • a connection to ground can be switched via a fourth switch S4.
  • a first ohmic resistor R1 is provided between the first measurement input A on the anode side and the first switch S1.
  • a second ohmic resistor R2 is integrated between the second measuring input K on the cathode side and the operational amplifier 35.
  • a third ohmic resistor R3 is located in a branch line 37 between the measurement input K on the cathode side and the line branch 36 between the first switch S1 and the operational amplifier 34 on the anode side.
  • a fifth switch S5 is provided in branch line 37, which connects one connection 53 of third resistor R3 to measurement input K on the cathode side.
  • the other connection 54 of the third resistor R3 is connected to the branch line 36.
  • the line branch 37 can be blocked or switched on via the fifth switch S5.
  • Switches S1, S2, S3, S4 and S5 shown are semiconductor elements, in particular transistors or power transistors. All switches S1, S2, S3, S4 and S5 are solid state components.
  • the circuit arrangement 100 (measuring arrangement) of a measuring channel is shown in FIG Fig. 4 shown in normal measuring mode.
  • the electronic switches S1 and S2 are closed via a higher-level digital control unit.
  • the electronic switches S3, S4 and S5 remain open.
  • the measuring input A on the anode side and the measuring input K on the cathode side are connected to one another in an electrically conductive manner via the measuring resistor 45.
  • the voltage drop across the measuring resistor 45 is detected via the operational amplifier 46 and fed to the evaluation unit 48 via the analog / digital converter 47.
  • the circuit arrangement 100 detects the voltage at the load.
  • the higher-level digital control unit uses recorded values such as output voltage and / or output current, changed environmental conditions, the expiry of a specified period of time or similar criteria to determine whether a compensation of the circuit arrangement 100 (measuring arrangement) is to be carried out.
  • a main criterion for initiating a compensation can be the ambient temperature of the electronic assembly of the measuring channel. This is recorded with a temperature sensor (not shown in detail) on the assembly itself. When a specified temperature change is reached, a compensation is started automatically by a higher-level digital control unit.
  • the higher-level digital control unit closes switches S3 and S4, while the other switches S1, S2 and S5 of the circuit arrangement (measuring arrangement) are open.
  • the reference voltage source 50 is connected to the circuit arrangement of the measuring channel via the switch S3, as is the case Fig. 5 shows.
  • the active current paths are shown with dashed lines.
  • the voltage (measured value) tapped at measuring resistor 45 after connecting the reference voltage source 50 to the measuring channel is directly proportional to the known size of the voltage of reference voltage source 50.
  • a deviation of the voltage (measured value) tapped at measuring resistor 45 from the expected proportional value of the reference voltage reveals a fault in the circuit arrangement 100 (measuring arrangement) and can be compensated accordingly.
  • This compensation can be carried out mathematically by determining a new damping factor for the circuit arrangement (measuring arrangement) in the higher-level digital control unit. This type of compensation is also referred to as "gain correction" in measurement technology.
  • the circuit arrangement 100 according to the invention (measuring arrangement) can also be compensated for by means of an "offset" in order to correct a constant error, as in FIG Fig. 6 is shown. As a result, a constant error in the circuit arrangement 100 (measuring arrangement) can be suppressed permanently.
  • the offset measurement can also be carried out in a simple manner with the circuit arrangement (measuring arrangement) according to the invention, such as Fig. 6 shows.
  • switches S2 and S5 are closed, while the other switches S1, S3 and S4 remain open.
  • the active current paths are shown with dashed lines.
  • a level of 0V is provoked at the measuring resistor 45 in the circuit arrangement 100, since the connections of the measuring resistor 45 are short-circuited.
  • the voltage measured in this state corresponds to the offset of the evaluation circuit and can be compensated accordingly.
  • the circuit arrangement 100 (measuring arrangement) according to the invention is also suitable for checking the measuring lines.
  • the measuring lines work load-free with a measuring current of around 100pA. Due to the very low currents, there is no significant voltage drop across the measuring lines, so that a voltage level is measured at the end of the measuring lines that ideally corresponds to the voltage level dropping across the load. In the event of a line break in the measuring line or a faulty or disconnected measuring line, this error can be recognized automatically.
  • the measurement results of the measurement channel are used as a feedback variable for the control loop, so that a faulty connection of the measurement line would lead to saturation of the linear controller, which can result in irreversible damage to the KKS components permanently installed in the structure (especially the anodes).
  • test current is provoked on the measuring line.
  • This test current is generated by a matched pair of ohmic resistors.
  • the resulting test current depends on the output voltage.
  • resistors also known as “equalization resistors”
  • An error detection sequence is initiated independently by the higher-level digital control unit.
  • the digital control unit first determines the common mode voltage (deviation from the zero potential of the protective power supply) of the measurement input K on the cathode side of the measurement arrangement.
  • This operation of the circuit arrangement (measuring arrangement) is shown in Fig. 7 shown schematically.
  • the higher-level digital control unit closes switches S4 and S5, so that the in Fig. 7
  • the circuit shown in dashed lines is active.
  • the switches S1, S2, and S3 are open.
  • the voltage drop across the measuring resistor 45 indicates the potential of the measuring input K on the cathode side with respect to ground.
  • the deviation of the measurement input K on the cathode side compared to the zero potential of the cathodic protection arrangement is determined.
  • the higher-level digital control unit closes switch S1 in addition to closed switches S4 and S5.
  • the switches S2 and S3 remain open, as in FIG Fig. 8 is shown. This results in the active current paths shown in broken lines.
  • the closed switch S1 and the closed switch S5 result in a conductive connection between the positive measurement input A and the negative measurement input K via the resistors R1 and R3 .
  • the voltage dropping of the circuit arrangement 100 (measuring arrangement) at the measuring resistor 45 must have a measuring level which corresponds to half of the voltage originally dropping at the measuring resistor 45 plus the common mode voltage. If there is a break in a measuring line or a bad connection between the measuring lines, will different voltages drop across the measuring resistor 45. The ratio of the voltage divider 43 shifts. The polarity of the deviation from the expected measured value can be used to determine whether the fault is on the positive or negative measuring line.
  • the closed switches S1 and S4 result in a current flow from the anode-side measuring input A to ground (zero potential of the protective arrangement) and cause a corresponding voltage drop at the measuring resistor 45. If, on the other hand, there is a break in the measurement line to the cathode-side measurement input A, then a current flow results via the switch S5 from the cathode-side measurement input K via the resistor R3 and the measurement resistor 45 and the switch S4 to the zero potential of the protective arrangement.
  • an analog error management with a high-impedance isolating device 30 is provided between the output 18 of the linear regulator 14 and the power output 40 of the voltage source 7.
  • the separating device 30 is connected to a control unit 31. Any errors that occur are stored in the control unit 31, evaluated and, if a switch-off criterion is present, an error signal 41 is output to the isolating device 30.
  • the isolating device 30 interrupts the electrical connection between the output 18 of the linear regulator 14 and the power output 40.
  • the separating device 30 ensures that the voltage source 7 of the cathodic corrosion protection can be separated from the load (reinforcement 4 in the concrete 2) with a very high resistance (high impedance). In the disconnected state, there is no influence on the electrical potential at the load.
  • the separating device 30 is implemented entirely in solid state construction, preferably with two power field effect transistors (MOSFET).
  • This construction ensures, on the one hand, a very high switch-off resistance and, on the other hand, a very fast response time.
  • the power transistors used can expediently be switched in so-called anti-series operation. Due to its design, each power transistor can only switch off positive currents. In order to be able to switch off both positive and negative currents, the circuit breakers are linked in opposite directions.
  • the isolating device 30 has no electrical connection to the control unit 31.
  • the error signal 41 is fed to the isolating device 30 in a galvanically isolated manner, in particular via optocouplers and / or transformers.
  • the error management described for controlling the separating device 30 is essentially composed of three functional blocks.
  • Part of the first functional block consists of a first digital / analog converter 61, which provides an analog threshold voltage which is determined by the higher-level digital control unit can be parameterized. This analog threshold voltage is directly proportional to an output voltage.
  • Another part of the first function block consists of a second digital / analog converter 62, which provides a further analog threshold voltage as a default value, which can be parameterized by the higher-level digital control unit.
  • the analog threshold voltages provided are directly proportional to a current measured in the measuring arrangement or the voltage source or a voltage measured in the measuring arrangement or the voltage source.
  • the second function block consists of comparators 71 and 72, which are advantageously designed as fast comparators which can operate with little overdrive.
  • the threshold voltage of the first digital / analog converter 61 which is present as an analog value, is fed to the first input of the comparator 71.
  • This analog threshold voltage is compared with a voltage measured in the measuring arrangement and / or the voltage source, which is fed to the comparator 71 via a measuring input 63. If the measured voltage at the measuring input 63 exceeds the analog threshold voltage, the comparator 71 emits a comparison signal at its output 75.
  • the comparison signal is fed via an OR link 79 to the control unit 31, which outputs the error signal 41 to the separating device 30.
  • the comparison signal is always saved in hardware.
  • the comparison signal preferably always leads to the power output 40 being switched off via the control unit 31.
  • the digital control unit 70 will only acknowledge an error. If the error condition persists, the analog circuit is immediately switched off again due to the comparison signal that is still present.
  • the threshold voltage of the second digital / analog converter 62 which is advantageously present as an analog value, is correspondingly fed to the first input of the comparator 72.
  • This analog threshold voltage is compared with a current measured in the measuring arrangement or the voltage source as a voltage value, which is fed to the comparator 72 via a measuring input 64. If the voltage value of the measured current supplied via the measurement input 64 exceeds the threshold voltage, the comparator 72 emits a corresponding comparison signal at its output 76.
  • This comparison signal is also fed to the control unit via the OR link 79 and is stored in the control unit 31 as an error that has occurred.
  • An overtemperature situation (parts of the assembly exceed a defined temperature) can thus be detected via a further comparator 73.
  • a permitted temperature is specified for the comparator 73 via a setpoint input 65.
  • a measured temperature value is fed to the assembly via a measuring input 66 and is compared in the comparator 73 with the permitted temperature.
  • the comparator 73 outputs a corresponding comparison signal via the OR link 79 to the control unit 31 via its output 77.
  • a feedback error can also be detected via a further comparator 74.
  • the comparator 74 is given a reference value for feedback on a setpoint input 67. The measured value of the feedback is reported to the comparator 74 at the measurement input 68. If the feedback exceeds the permissible reference value, this is recognized by the comparator 74.
  • the comparator 74 gives a corresponding output at its output 78 Comparison signal, which is transmitted to the control unit 31 via the OR link 79.
  • the third function block is formed by the control unit 31, which stores the received comparison signals from the error monitoring unit 32 and / or links them to one another.
  • the control unit 31 emits an error signal 41 to the separating device 30 if - according to predetermined criteria - the received comparison signals from the error monitoring unit 32 make it necessary to switch off the power output 40 by triggering the separating device 30.
  • the generation of the error signal 41 is stored in the control unit 31, for example by setting a digital flag.
  • the stored values can only be reset by the higher-order digital control unit 70 of the assembly.
  • the error detection as well as the shutdown of the power output 40 takes place very quickly due to the analog signal processing.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Control Of Voltage And Current In General (AREA)
EP20176896.7A 2020-05-27 2020-05-27 Circuit de protection cathodique contre la corrosion et agencement de mesure lors de la protection cathodique contre la corrosion Pending EP3916128A1 (fr)

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EP20176896.7A EP3916128A1 (fr) 2020-05-27 2020-05-27 Circuit de protection cathodique contre la corrosion et agencement de mesure lors de la protection cathodique contre la corrosion

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Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0018522A1 (fr) * 1979-04-26 1980-11-12 Vereinigte Elektrizitätswerke Westfalen AG Procédé et appareil pour le maintien de la protection cathodique contre la corrosion
GB2252686A (en) * 1991-02-08 1992-08-12 Stc Plc Power feed branching unit for submarine telecommunications systems
WO1993002407A1 (fr) * 1991-07-17 1993-02-04 Halcro Nominees Pty Ltd Regulateur alimentation en courant ameliore
CA2073530A1 (fr) * 1992-07-09 1994-01-10 John C. K. Overall Systeme de protection contre la corrosion
EP0699986A2 (fr) * 1994-08-31 1996-03-06 STMicroelectronics, Inc. Circuit et méthode pour la régulation de tension
US5517383A (en) * 1993-03-03 1996-05-14 Stc Submarine Systems Limited Branching unit for submarine systems
EP1063321A2 (fr) * 1999-06-17 2000-12-27 Gronvold & Karnov AS Améliorations dans la protection cathodique de structures en béton et de maçonnerie
WO2007010335A2 (fr) * 2005-07-20 2007-01-25 Merloni Termosanitari S.P.A. Chauffe-eau a accumulation a protection cathodique reglable
US20140262823A1 (en) * 2013-03-15 2014-09-18 Jonathan Paul Freeman Digitally controlled corrosion protection system and method
CN105040000A (zh) * 2015-07-10 2015-11-11 中国民航大学 一种便携式阴极保护装置
CN111181402A (zh) * 2018-11-12 2020-05-19 航天科工惯性技术有限公司 一种用于井下石油管道的防垢电源设备

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0018522A1 (fr) * 1979-04-26 1980-11-12 Vereinigte Elektrizitätswerke Westfalen AG Procédé et appareil pour le maintien de la protection cathodique contre la corrosion
GB2252686A (en) * 1991-02-08 1992-08-12 Stc Plc Power feed branching unit for submarine telecommunications systems
WO1993002407A1 (fr) * 1991-07-17 1993-02-04 Halcro Nominees Pty Ltd Regulateur alimentation en courant ameliore
CA2073530A1 (fr) * 1992-07-09 1994-01-10 John C. K. Overall Systeme de protection contre la corrosion
US5517383A (en) * 1993-03-03 1996-05-14 Stc Submarine Systems Limited Branching unit for submarine systems
EP0699986A2 (fr) * 1994-08-31 1996-03-06 STMicroelectronics, Inc. Circuit et méthode pour la régulation de tension
EP1063321A2 (fr) * 1999-06-17 2000-12-27 Gronvold & Karnov AS Améliorations dans la protection cathodique de structures en béton et de maçonnerie
WO2007010335A2 (fr) * 2005-07-20 2007-01-25 Merloni Termosanitari S.P.A. Chauffe-eau a accumulation a protection cathodique reglable
US20140262823A1 (en) * 2013-03-15 2014-09-18 Jonathan Paul Freeman Digitally controlled corrosion protection system and method
CN105040000A (zh) * 2015-07-10 2015-11-11 中国民航大学 一种便携式阴极保护装置
CN111181402A (zh) * 2018-11-12 2020-05-19 航天科工惯性技术有限公司 一种用于井下石油管道的防垢电源设备

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