JP2020004795A - Monitoring system and monitoring device for stationary induction device - Google Patents

Abstract

To provide a monitoring system and a monitoring device capable of accurately and easily monitoring a stationary induction device.SOLUTION: A monitoring system of a stationary induction device includes a first instrument transformer having a high-voltage winding and a low-voltage winding, and connected between tap terminals that are not connected to a power system among tap terminals of a high-voltage winding, and a monitoring unit that determines a voltage between terminals of the high-voltage winding on the basis of a ratio of the number of turns of the first instrument transformer, a ratio of the number of turns of the high-voltage winding and the number of turns between the tap terminals, a correction value corresponding to a leakage impedance between the high-voltage winding and the tap terminal, and a voltage generated in the first instrument transformer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a static induction device such as a transformer or a reactor, and more particularly to a technique for monitoring the static induction device.

  At the receiving end of a general power system, 3 to 6 kV-class power from a distribution substation is transmitted by a plurality of high-voltage distribution lines to a stationary induction device such as a receiving and distribution transformer provided on a pole. Connected, stepped down to 100-200V and distributed to each customer. Conventionally, in order to ensure the reliability of the power system and maintain proper voltage and frequency, the distribution situation is monitored and adjusted in substations and the like.

  However, in recent years, introduction of renewable energy power sources, such as wind power and solar power generation, into power systems has been progressing. Since these generated powers fluctuate every moment due to weather conditions and the like, it is difficult to grasp and maintain the soundness of the power system. In view of such a situation, it is conceivable to grasp the amount of power consumed by each consumer.

  As a method of reliably grasping the amount of power consumed by each consumer, the input and output power of each static induction device is measured directly by measuring the voltage and current, and the measured values are collected by wired or wireless communication means for system management. It is desired to contribute to. If such a technique can be realized, not only system monitoring but also information on abnormalities and remaining life of individual stationary induction devices can be obtained, and it is possible to prevent the occurrence of power failure or the like due to a sudden failure.

  However, in order to measure the input voltage on the high voltage primary side of the 3 to 6 kV class, it is necessary to take sufficient insulation measures, and there is a problem that the components for the measurement become expensive. As a means for solving this problem, a method is conceivable in which the voltage on the high voltage primary side is calculated from the measured value of the output voltage on the low voltage secondary side and the turn ratio between the primary winding and the secondary winding. For example, Patent Literature 1 discloses that a pulse signal from a control circuit connected to a secondary rectifier circuit of an insulation transformer is transmitted to a primary side for controlling a switching operation of an insulation type DC-DC converter. There has been disclosed a technique of calculating an input power supply voltage from a given turns ratio of a pulse transformer and controlling the converter in accordance with the input power supply voltage.

WO2009 / 011374

  The technique according to Patent Document 1 is effective in applications in which input and output voltage waveforms are strictly controlled, such as a DC-DC converter. However, in the static induction device used in the power system, as described above, as the number of renewable energy sources increases, uncontrollable voltage and frequency fluctuations and superimposition of harmonics become remarkable. Therefore, there is a problem that the leakage impedance between the primary side and the secondary side winding of the stationary induction device fluctuates irregularly, and the calculation accuracy of the primary side voltage based on the turns ratio cannot be sufficiently ensured. Therefore, it is desirable to measure the input voltage on the high voltage primary side of the stationary induction device. However, as described above, in order to measure the input voltage on the high voltage primary side of 3 to 6 kV class, for example, sufficient insulation measures are taken. Since it is necessary, there is a problem that the countermeasures are complicated and components for measurement are expensive.

  An object of the present invention is to provide a monitoring system and a monitoring device capable of accurately and easily monitoring a static induction appliance.

A preferred example of the present invention is a monitoring system for a static induction device having a high voltage winding and a low voltage winding,
Among the tap terminals of the high-voltage winding, a ratio of the number of turns of a first instrument transformer connected between tap terminals that are not connected to an electric power system and the first instrument transformer; The number of turns of the pressure winding and the ratio of the winding between the tap terminals, a correction value corresponding to the leakage impedance between the high-voltage winding and the tap terminal, and a voltage generated in the first instrument transformer. And a monitoring unit for obtaining a voltage between terminals of the high-voltage winding.

Another preferred embodiment of the present invention has a high-voltage winding and a low-voltage winding, and among the tap terminals of the high-voltage winding, a first instrument is provided between tap terminals that are not connected to a power system. A monitoring device attached to a stationary induction device to which a transformer is connected,
A voltage measuring unit for acquiring a voltage generated in the first instrument transformer;
A ratio of the number of turns of the first instrument transformer, a ratio of a number of turns of the high-voltage winding and a ratio of a winding between the tap terminals, and a correction value corresponding to a leakage impedance between the high-voltage winding and the tap terminal. And a calculation unit for obtaining a voltage between terminals of the high-voltage winding based on a measurement result from the voltage measurement unit.

  According to the present invention, it is possible to accurately and easily monitor a stationary induction device.

FIG. 4 is a circuit diagram of a method for measuring a current and a voltage of the single-phase transformer according to the first embodiment. FIG. 2 is a vertical configuration diagram of an oil-filled single-phase transformer according to the first embodiment. FIG. 2 is a horizontal configuration diagram of the oil-filled single-phase transformer according to the first embodiment. 1 is a circuit diagram of an operation monitoring system for an oil-filled single-phase transformer according to a first embodiment. 1 is an overall view of an operation monitoring system for an oil-filled single-phase transformer according to a first embodiment. FIG. 9 is a circuit diagram of an operation monitoring system for an oil-filled single-phase transformer according to a second embodiment. FIG. 13 is a circuit diagram of a method for measuring current and voltage of a three-phase transformer according to the third embodiment. FIG. 10 is a vertical configuration diagram of an oil-filled three-phase transformer according to a third embodiment. FIG. 14 is a front view of a molded three-phase transformer according to a fourth embodiment. FIG. 4 is a circuit diagram showing a measurement method for a current and a voltage of a single-phase transformer in a comparative example.

  Hereinafter, embodiments will be described in detail with reference to the drawings.

  FIGS. 1 to 5 are diagrams for explaining the first embodiment. The configuration and operation of this embodiment will be described using a comparative example shown in FIG.

  FIG. 1 is a circuit diagram illustrating a method for measuring a current and a voltage of a single-phase transformer according to the first embodiment. Around the iron core 3, two divided high-voltage windings 1a and 1b and two divided low-voltage windings 2a and 2b are wound. A plurality of tap terminals 1d are provided at a connection portion between the high-voltage windings 1a and 1b for every fixed number of turns. By connecting any tap terminals with a tap connection line 1c, the high-voltage and low-voltage windings of the transformer are provided. The turns ratio between the wires is finely adjusted, and the connection between the low-voltage windings 2a and 2b is connected by a connection wire 2c for operation. The tap terminal 1d is a lead wire drawn out from the middle of the winding so that, for example, when the voltage received by the transformer fluctuates, the number of turns suitable for the voltage can be selected. In this embodiment, it is provided between the electrodes U and V on the high voltage side. The high voltage of the transformer is applied between the electrodes U and V, and the reduced low voltage is output between the electrodes u and v.

  FIG. 10 is a circuit diagram as a comparative example showing a method of measuring the voltage and current input to the single-phase transformer and the output voltage and current. A first instrument transformer (VT) 10 is connected between the U and V electrodes, and a second instrument transformer 20 is connected between the u and v electrodes, and measures the high-side voltage V1 and the low-side voltage V2, respectively. . The high voltage side electrode is provided with a first current transformer (CT) 11, and the low voltage side electrode is provided with a second current transformer 21. The high voltage side current I1 and the low voltage side current I2 are measured. . The input power Pin and the output power Pout of the single-phase transformer are obtained by time-integrating the product of the time waveforms of the current and the voltage over the period T, according to the following equations (1) and (2), respectively. Desired. However, the turns ratio of the first instrument transformer 10 and the second instrument transformer 20 is n. Here, the turns ratio n refers to a value obtained by dividing the number of turns of the high-voltage winding by the number of turns of the low-voltage winding. The period T is, for example, 1/50 second or 1/60 second, and the input power or output power of the stationary induction device can be obtained by performing time integration over such time.

In the measurement method in the comparative example of the voltage and current input to the single-phase transformer and the output voltage and current, a voltage V0 of ₃ to 6 kV class is applied between the high-side electrodes U and V. It is necessary to make the turns ratio n of the first instrument transformer 10 very large, sufficiently lower the measured voltage V1, and obtain the measured voltage V1 by equation (3).

Furthermore, it is necessary to take measures to insulate components for measuring voltage. Therefore, in the comparative example, the cost of the electronic circuit for acquiring the voltage waveform, the electronic circuit disposed ahead of the electronic circuit, and the like, including the instrument transformer 10, increase, and it is difficult to ensure safety.

In the first embodiment, the voltage and current input to the single-phase transformer and the output voltage and current are measured by the circuit diagram shown in FIG. The method of measuring the voltage V2 and current I2 on the low voltage side and the current I1 on the high voltage side are the same as those in the comparative example. A first instrument transformer 10 is connected between tap terminals 1d provided in the high-voltage winding of the single-phase transformer and not connected to the power system, and a voltage V1 generated between the tap terminals is connected. Is measured. The number of turns of the entire high-voltage winding is N1, the number of turns between the tap terminals 1d to which the first instrument transformer 10 is connected is Nt, and the leakage impedance between the high-voltage winding and the winding between the tap terminals 1d. When the correction coefficient is r, the relationship between the voltage V1 measured, the high-pressure side electrode U, and the high side voltage V ₀ which between V can be obtained by equation (4).

Further, the input power Pin 'of the transformer is obtained as follows.

  Since the winding between the tap terminals 1d connecting the first instrument transformer 10 is a part of the high-voltage windings 1a and 1b, the leakage impedance to the high-voltage winding is sufficiently small. Therefore, the input power Pin 'can be calculated by considering the correction coefficient r in the equation (5). The loss Loss generated in the single-phase transformer is obtained by the following equation.

  FIG. 2 is a vertical configuration diagram of the oil-filled single-phase transformer according to the first embodiment. FIG. 2 shows a state of wiring of only the electrodes U and V on the high voltage side of the single-phase transformer. The low-voltage windings 2a and 2b are wound around the single-phase iron core 3, and the high-voltage windings 1a and 1b are wound around the single-phase iron core 3 separately on two magnetic legs. The low voltage windings 2a and 2b are connected by a connection line 2c. At the upper and lower portions of the single-phase iron core 3, fixing members 5 are provided, and are fixed to the inner wall of the insulating oil tank 6 together with the windings, although not shown. The upper fixing bracket 5 is provided with a tap terminal block 4, and the terminal block is provided with a tap terminal connected to a high-voltage winding. The high-voltage windings 1a and 1b are connected by a tap connection line 1c. Then, the first instrument transformer 10 is connected to the tap terminal 1d not connected to the power system, and the voltage V1 is measured. The high voltage side electrode is provided with a first current transformer 11, and measures the high voltage side current I1. Then, the input power Pin 'to the single-phase transformer is obtained by the equation (5).

  FIG. 3 is a horizontal configuration diagram of the oil-filled single-phase transformer according to the first embodiment. Since the symbols of the components described in FIG. 2 are the same, description thereof will be omitted. In this figure, the high pressure side electrodes U and V are provided below the insulating oil tank 6 and are connected to the terminal block 4 to which the first instrument transformer 10 is connected. On the upper side of the insulating oil tank 6, low voltage side electrodes u and v are provided, and are directly connected to the low voltage windings 2a and 2b. The second instrument transformer 20 is directly connected to the low-voltage side electrodes u and v outside the insulating oil tank 6.

  FIG. 4 is a circuit diagram of the operation monitoring system of the oil-filled single-phase transformer according to the first embodiment. The voltage V1 is measured by the first instrument transformer 10 connected to the tap terminal block 4 inside the insulating oil tank 6. The voltage V2 is measured by the second instrument transformer 20 connected to the low voltage side electrodes u and v. The current I1 is measured by the first current transformer 11 provided on the high-voltage side electrode. The current I2 is measured by the second current transformer 21 provided on the low-voltage side electrode. V1, V2, I1, and I2 are input to the voltage and current waveform measuring means 30 provided on the substrate 35 constituting the monitoring unit or the monitoring device.

  The measuring means 30 is controlled by the control means 31 on the substrate 35, and measures the voltage and current waveform at regular intervals. The control means 31 functioning as an arithmetic unit calculates the input power Pin ′ and the output power Pout of the single-phase transformer based on the measured waveform and the equations (2), (5), and (6). , Loss Loss, time-series data of a voltage waveform, or time-series data of a current waveform are stored in the recording unit 32.

  These measured and accumulated numerical data are transmitted by the communication means 33 and the antenna 34, and are used for monitoring the state of the power system and monitoring the soundness of the single-phase transformer. It should be noted that the method of transmitting the measured numerical data is not limited to the method via the antenna 34 shown in this figure, but may be a method using wired communication or optical communication such as infrared rays. Each unit provided on the substrate 35 is driven by electric power supplied from the battery 36.

  FIG. 5 is an overall view of an operation monitoring system of the oil-filled single-phase transformer according to the first embodiment. The substrate 35 provided with the instrument transformers 10 and 20, the voltage and current measuring means 30, the control means 31, the recording means 32, and the communication means 33 shown in FIG. 4 is an insulating oil tank of the single-phase transformer. 6, the battery 36 and the antenna 34 are connected.

  The substrate 35 may be housed inside a box-shaped member as a fixed protection member on the outer surface of the insulating oil tank 6 as a housing of the stationary induction device. Alternatively, the substrate 35 may be covered with a resin material as a waterproof protection member, and fixed by bonding to the outer surface of the insulating oil tank 6. Further, the substrate 35 constituting the monitoring device or the monitoring unit can be disposed in an open space in the insulating oil tank 6 by providing a protective member such as waterproof on the surface thereof. By doing so, the space outside the insulating oil tank 6 can be used for another purpose.

  According to the first embodiment, the voltage on the high voltage side of the stationary induction device, the consumed power, and the like can be monitored at a low cost with a simple configuration. In addition, it is possible to monitor and adjust the power system with high accuracy. Further, information on the abnormality of the transformer and the remaining life can be obtained, and it is possible to prevent a power failure or the like due to a sudden failure of the transformer. In addition, the monitoring unit or the monitoring device of the present embodiment can be easily added to the existing static induction device, so that high-precision monitoring and adjustment of the power system can be performed without a large-scale replacement work of the static induction device. There are also possible effects.

  FIG. 6 is a circuit diagram of an operation monitoring system for an oil-filled single-phase transformer according to the second embodiment. The same components as those in the first embodiment are denoted by the same symbols as those in FIG. 4, and description thereof will be omitted. In the first embodiment, each unit provided on the substrate 35 is driven by electric power supplied from the battery, but there is a problem that periodic battery replacement work is required.

  Therefore, in the second embodiment, the high-voltage side electrode of the single-phase transformer is provided with a power receiving coil 37a, and an induced electromotive force is obtained from a magnetic field created by a current I1 flowing through the electrode, and this is used to drive each unit on the substrate 35. Power.

  On the substrate 35, a filter for removing high-frequency components superimposed on the AC power output from the power receiving coil 37a and converting the component into DC power and an AC-DC converter 37 are provided. Drive each of the other means above.

  According to the second embodiment, while the single-phase transformer is connected to the electric power system, the monitoring system can be continuously driven, and a battery replacement operation or the like becomes unnecessary.

  7 and 8 are diagrams for explaining the third embodiment. FIG. 7 is a circuit diagram of a method for measuring the current and voltage of the three-phase transformer according to the third embodiment, and illustrates the three-phase high-voltage windings 1 u, 1 v, and 1 w employed in a general power receiving and distribution transformer. An example is shown in which the three-phase low-voltage windings 2u, 2v, and 2w are star-connected and delta-connected. Description of the parts common to the first embodiment and the like is omitted. On the opposite side of the electrodes U, V, W of the three-phase high-voltage windings 1u, 1v, 1w, a plurality of tap terminals 1d are provided for every fixed number of turns, and arbitrary tap terminals are connected by a tap connection line 1c. Thus, the turns ratio between the high-voltage and low-voltage windings of the transformer is finely adjusted, and the three-phase low-voltage windings 2u, 2v, and 2w are delta-connected by the connection line 2c for operation. The three-phase voltage on the high voltage side of the three-phase transformer is applied to the electrodes U, V, W, and the reduced three-phase voltage on the low voltage side is output from the electrodes u, v, w.

  A first instrument transformer 10u, 10v, 10w is provided between tap terminals 1d, which are provided in the middle of the three-phase high-voltage windings 1u, 1v, 1w of the three-phase transformer and are not connected to the power system. Each of them is connected, and phase voltages V1u, V1v, V1w generated between the tap terminals are measured. Similarly to the first embodiment, the high-voltages between the high-voltage electrodes of each phase, that is, the high-voltages between U-V, V-W, and U-W can be calculated based on Equation (4). it can.

  Further, the second instrument transformers 20uv, 20vw, 20wu are respectively connected between the three-phase electrodes u, v, w on the low voltage side, and the line voltages V2uv, V2vw, V2wu generated between the electrodes are measured. . The high-voltage three-phase electrodes U, V, and W are provided with first current transformers 11u, 11v, and 11w, respectively, to measure phase currents I1u, I1v, and I1w. , W are provided with second current transformers 21u, 21v, 21w, respectively, to measure line currents I2u, I2v, I2w.

  The input power Pin3 and the output power Pout3 of the three-phase transformer are obtained by time-integrating the product of the voltage and current time waveforms measured by the instrument transformer and current transformer over a period T. Can be The number of turns of each of the three-phase windings 1u, 1v, and 1w on the high voltage side is N1, the number of turns between tap terminals 1d to which the first instrument transformers 10u, 10v, and 10w are connected is Nt, and the turns ratio of the instrument transformer is Nt. n, and assuming that the correction coefficients corresponding to the leakage impedance between the high-voltage windings 1u, 1v, and 1w and the winding between the tap terminals 1d in each winding are ru, rv, and RW, respectively, the input power Pin3 is

It is expressed as Also, the output power Pout3 is

And the loss Loss3 generated in the three-phase transformer is obtained by the following equation.

  FIG. 8 is a vertical configuration diagram of an oil-filled three-phase transformer according to the third embodiment. FIG. 8 shows a state of wiring of only the electrodes U, V, and W on the high voltage side of the three-phase transformer. Three-phase low-voltage windings 2u, 2v, and 2w are wound around the three-phase core 3, and three-phase high-voltage windings 1u, 1v, and 1w are further wound around the three-phase iron core 3. Fixing fittings 5 are provided on the upper and lower parts of the three-phase iron core 3, and are fixed to the inner wall of the insulating oil tank 6 together with the windings, though not shown. The upper fixing bracket 5 is provided with a tap terminal block 4, and the terminal block is provided with a tap terminal connected to a high-voltage winding. Then, the first instrument transformers 10u, 10v, and 10w are connected to the tap terminals 1d that are not connected to the power system, and the phase voltages V1u, V1v, and V1w are measured. The high voltage side electrodes U, V, W are provided with first current transformers 11u, 11v, 11w, and measure the phase currents I1u, I1v, I1w. Then, in the same manner as in the first embodiment, the control unit 31 calculates the input power Pin3 to the three-phase transformer according to the equation (7).

  According to the third embodiment, it is possible to monitor the voltage on the high voltage side, the consumed power, and the like in a three-phase static induction device such as a three-phase transformer at a low cost.

  FIG. 9 is a front view of a molded three-phase transformer showing the fourth embodiment. In the fourth embodiment, the same components as those in the third embodiment are denoted by the same reference numerals as those in FIG. 8, and the description thereof will be omitted. In the fourth embodiment, a plurality of tap terminals 1d are provided on the surface of the three-phase high-voltage windings 1u, 1v, and 1w molded with resin or the like, and arbitrary tap terminals are connected by a tap connection line 1c. The phase high-voltage winding is star-connected. In the fourth embodiment, the first instrument transformers 10u, 10v, and 10w are connected between the tap terminals 1d that are not connected to the power system provided on the surface of the high-voltage winding, so that the phase voltages V1u and V1v are connected. , V1w are measured.

  According to the fourth embodiment, it is possible to monitor the voltage on the high voltage side, the consumed power, and the like in a three-phase molded stationary induction device such as a molded three-phase transformer with a simple configuration and at low cost. .

  The embodiments described above do not limit the configuration. In addition, it does not exclude that a plurality of embodiments are combined and configured.

1a, 1b: single-phase high-voltage winding, 1c: tap connection line, 1d: tap terminal, 2a, 2b: single-phase low-voltage winding, 2c: low-voltage winding connection line, 10: high-voltage winding-side instrument transformer (VT), 11: Current transformer (CT) on high voltage winding side, 20: Instrument transformer (VT) on low voltage winding side, 21: Current transformer (CT) on low voltage winding side, 3: Iron core, 30: voltage / current waveform acquisition means, 31: control means, 32: recording means, 33: communication means, 35: substrate

Claims (10)

A monitoring system for a static induction device having a high voltage winding and a low voltage winding,
Among the tap terminals of the high-voltage winding, a first instrument transformer connected between tap terminals that are not connected to a power system,
A ratio of the number of turns of the first instrument transformer, a ratio of a number of turns of the high-voltage winding and a ratio of a winding between the tap terminals, and a correction value corresponding to a leakage impedance between the high-voltage winding and the tap terminal. A monitoring unit for determining a voltage between terminals of the high-voltage winding based on a voltage generated in the first instrument transformer. The monitoring system for a stationary induction machine according to claim 1,
A second current transformer for measuring the voltage on the low voltage side, a first current transformer for measuring the current on the high voltage side, and a second current transformer for measuring the current on the low voltage side;
The monitoring unit is
Based on the voltage and current measured by the first instrument transformer and the first current transformer, determine the input power of the stationary induction device,
Based on the voltage and current measured by the second instrument transformer and the second current transformer, determine the output power of the stationary induction device,
A monitoring system for a static induction device, wherein power consumption consumed by the static induction device is obtained based on the input power and the output power. The monitoring system for a stationary induction device according to claim 2,
The monitoring unit is
The input power is obtained by time-integrating a value obtained by multiplying the instantaneous value of the voltage and current measured by the first instrument transformer and the first current transformer over a predetermined time,
The output power is obtained by integrating the value obtained by multiplying the instantaneous value of the voltage and current measured by the second instrument transformer and the second current transformer over a predetermined time,
A stationary induction machine monitoring system, wherein the power consumption is obtained by subtracting the output power from the input power. The monitoring system for a stationary induction machine according to claim 1,
The monitoring unit is
Measuring means for measuring the waveform of the voltage generated in the first instrument transformer;
A calculation unit for calculating the voltage between the terminals of the high-voltage winding;
Recording means for recording time-series data of the voltage generated in the first instrument transformer or the voltage between terminals of the high-voltage winding. The monitoring system for a stationary induction machine according to claim 4,
The monitoring unit is
A monitoring system for a static induction appliance, further comprising means for transmitting the time-series data recorded in the recording means or the voltage between terminals of the high-voltage winding to the outside. The monitoring system for a stationary induction machine according to claim 1,
The monitoring unit is surrounded by a protective member for waterproofing,
A stationary induction machine monitoring system, wherein the monitoring system is disposed outside a housing of the stationary induction machine. The monitoring system for a stationary induction machine according to claim 1,
The monitoring unit is
A monitoring system for a stationary induction device, which is driven by power supplied from a power receiving coil disposed on a high voltage side of the stationary induction device. The monitoring system for a stationary induction machine according to claim 1,
The stationary induction device has the three-phase high-voltage winding and the low-voltage winding,
The first instrument transformer is disposed between the tap terminals of the three-phase high-voltage winding,
A first current transformer is arranged on the high-pressure side of the three-phase;
A second instrument transformer is located on the low pressure side of the three phase;
A second current transformer is disposed on the low-pressure side of the three phase;
The monitoring unit is
Based on the voltage measured by the first instrument transformer and the second instrument transformer and the current measured by the first current transformer and the second current transformer, the three-phase And a power consumption consumed by said stationary induction device. The monitoring system for a stationary induction machine according to claim 8,
The static induction device is a molded three-phase transformer,
The three-phase high-voltage winding is molded, and the tap terminal is disposed on a mold surface. A stationary induction electric device having a high-voltage winding and a low-voltage winding, and among the tap terminals of the high-voltage winding, a first instrument transformer is connected between tap terminals that are not connected to the power system. A monitoring device to be installed,
A voltage measuring unit for acquiring a voltage generated in the first instrument transformer;
A ratio of the number of turns of the first instrument transformer, a ratio of a number of turns of the high-voltage winding and a ratio of a winding between the tap terminals, and a correction value corresponding to a leakage impedance between the high-voltage winding and the tap terminal. A monitoring unit that calculates a voltage between terminals of the high-voltage winding based on a measurement result from the voltage measurement unit.

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