JP4838640B2 - Insulation state monitoring device - Google Patents

Description

  The present invention relates to an insulation state monitoring device that monitors insulation of a direct grounding system low voltage circuit in a constantly energized state, and in particular, in addition to the conventional insulation state monitoring function, the grounding phase of the circuit is in contact with the ground for insulation monitoring. The present invention relates to a technique to which a function for facilitating discovery of a mixed electric circuit when a voltage of a monitoring voltage signal is lowered is added.

  When the insulation degradation of the electric circuit progresses in the low-voltage one-line ground circuit and a leakage accident occurs, the leakage relay installed in the substation or the like operates to break the circuit breaker. When the circuit breaker breaks, not only does it cause a wide range of power outages, but it also takes a long time to investigate and restore the point of accident as post-processing. For this reason, an insulation state monitoring device for constantly monitoring the insulation state of the electric circuit is used as a measure for preventing the occurrence of an accident.

  FIG. 8 is an explanatory diagram of an insulation state monitoring device for a one-wire grounded circuit that is generally known, and is configured as follows. That is, in the figure, reference numeral 21 denotes a transformer which supplies power to the monitored electric circuit 20 which is a low voltage distribution line. 22 is a B-type ground wire, 23 is an insulation monitoring signal generator for generating an insulation monitoring voltage signal (hereinafter referred to as an insulation monitoring signal), and a superposition transformer 24 and B (hereinafter referred to as a monitoring signal generator). The voltage of the insulation monitoring signal is superimposed on the monitored electric circuit via the seed ground line 22. The voltage of the insulation monitoring signal generates a low frequency low voltage signal of about 20 Hz and 10 V, and is transformed to about 0.5 V and applied. An insulation monitoring device 25 detects the voltage of the return insulation monitoring signal from the monitoring signal generator 23 and takes in a signal through the zero-phase current transformer 26. This zero-phase current transformer does not necessarily have to be provided on the ground line, and is the same even if it is provided on the feed line as indicated by the dotted line. In the figure, C represents the capacitance of the electric circuit to ground, and R represents the insulation resistance of the electric circuit to ground.

  Now, when the voltage of the insulation monitoring signal is generated from the monitoring signal generator 23 and superimposed on the B-type ground line 22, the insulation monitoring signal passes between the monitored circuit 20, the ground capacitance C of the circuit, and the ground insulation resistance R. It circulates and current flows as Ig.

  That is, the current Ig of the insulation monitoring signal applied from the monitoring signal generator 23 flows through the impedance due to the ground capacitance C and the ground insulation resistance R of the electric circuit. The current Ig of the insulation monitoring signal is a combined current of the capacitance component current Igc flowing through the ground capacitance C and the resistance component current Igr due to insulation deterioration, and the vector of these currents is as shown in FIG. Become.

The phase θ in the figure is the phase difference between the voltage (reference voltage) Vs of the applied insulation monitoring signal and the current Ig detected by the zero-phase current transformer 26, and is 90 degrees when there is no insulation deterioration. As the insulation deterioration progresses, the resistance component current Igr increases, and the phase difference θ changes accordingly. Therefore, the insulation state of the electric circuit can be monitored by monitoring changes in the resistance component current Igr and the phase difference θ (for example, Patent Documents 1 and 2).
Japanese Patent Publication No. 7-43403 Japanese Patent Publication No. 7-21522.

  Although the insulation state monitoring device described above is a single unit, a large number of power stations (for example, on each floor) are provided as in a high-rise building, and the secondary ground line of the transformer of each power station is shared. In many cases, a common grounding method of grounding with a grounding wire is employed. In this case, as shown in FIG. 10, the monitoring signal generator 3 is provided on the common ground line Ec, and the insulation monitoring is performed by the insulation monitoring means 5-1, 5-2, 5-3 provided in each monitored electric circuit. Is called.

  In this composite power feeding method, the monitoring signal generator 3 normally transmits the voltage of the insulation monitoring signal, but the voltage drops for some reason and the insulation monitoring means 5-1, 5-2, 5- The phenomenon that 3 could not operate normally occurred. As a result of investigating the cause, the grounding phase N of the power supply path is in contact with the earth and the ground impedance is short-circuited. A large monitoring current flows through the insulation monitoring signal, and the voltage of the insulation monitoring signal detected by the insulation monitoring means decreases. By this decrease in the insulation monitoring signal voltage, the value of the resistance component current is calculated based on the voltage of the insulation monitoring signal. It was found that each of the insulation monitoring means to be able to detect the voltage of the normal insulation monitoring signal was stopped, the function of resistance component current value calculation was stopped, and the insulation monitoring function was lost. In order to restore this calculation function, it is necessary to investigate the mixed contact feeding path that is the cause and repair the mixed contact portion. However, since the insulation monitoring means loses its function simultaneously with the contact between the ground phase and the earth, there is a problem that the insufficiency electric circuit cannot be specified by the insulation monitoring means.

  The present invention has been made on the basis of the above problems. In a normal state, the insulation state between the conventional feeding path and the ground is monitored, and when the voltage of the insulation monitoring signal decreases, the mixed feeding feeding path is displayed. Thus, an object of the present invention is to provide an insulation state monitoring device that can identify a mixed feeding power supply path.

In order to solve the above-mentioned problem, the present invention grounds a B-type ground with a common grounding line that shares the secondary grounding line of a transformer included in a plurality of feeding stations, and the common grounding line has a frequency different from that of the feeding path. Insulation monitoring signal generating means for generating a low-frequency insulation monitoring signal is provided, and this insulation monitoring signal is superimposed on a common ground line via a superposition transformer, and the insulation monitoring signal is zero-phased at each power station. Insulation monitoring means for detecting via a current transformer is provided, and the insulation monitoring means inputs the voltage and current of the detected insulation monitoring signal, calculates the resistance component current value from the inputted voltage and current, and insulation It has a function for determining whether the voltage of the monitoring signal is normal or lower than a predetermined value and a mixed contact display means for displaying the mixed contact state. When the voltage of the insulating monitoring signal is normal, the insulation monitoring signal Resistance formation from the voltage and current components of Calculate the current value Igr, display this current value on the display means, monitor the insulation state of the electric circuit with the magnitude of the current value, and the ground phase is in contact with the ground, and the voltage of the insulation monitoring signal is greater than the predetermined value When it is judged that the drop has fallen, it automatically switches to the contact display means, which calculates the insulation impedance value based on the current of the insulation monitoring signal, and converts this insulation impedance value to the current value Ig. However, the present invention is characterized in that the mixed state is displayed on the display means based on the magnitude of the current value.
The display state of the contact state in the contact display means is calculated by converting the insulation impedance value into a current value, calculating the converted current value Ig and displaying it on the display means, and displaying the contact electric circuit with the magnitude of the displayed current value. Try to determine.
Further, in another embodiment of the mixed contact display means, when it is determined that the voltage of the insulation monitoring signal falls below a set value, the insulation impedance value is calculated based on the current of the insulation monitoring signal, The impedance value is converted into a current value, the magnitude of the converted current value Ig is determined, and the contact means is displayed on the display means only when the current value Ig is larger than a preset set value so as to identify the contact electric circuit. .
Further, in another embodiment of the mixed display means, when it is determined that the voltage of the insulation monitoring signal falls below the set value, the insulation impedance value is calculated based on the current of the insulation monitoring signal, and the impedance value Is converted into a current value, the magnitude of the converted current value Ig is determined, and when it is larger than a preset set value, the zero-phase current I0 is input according to the frequency of the feed path, and the zero-phase current I0 and the insulation impedance value are The current value Ig converted into a current value is compared, and when the current value of the difference exceeds a preset set value, it is displayed that the contact is present and the mixed contact electric circuit is specified.
Further, in another embodiment of the mixed display means, when it is determined that the voltage is lower than the voltage setting value of the insulation monitoring signal, the insulation impedance value is calculated based on the current component of the insulation monitoring signal, and the impedance value is calculated. The current value Ig converted into a current value is determined, and when the value is larger than a preset value, the insulation impedance value of each power supply path grounded by a common ground line is converted into a current value and converted. When the value Ig is input and compared with the current value Ig of the self-feeding path, it is determined whether the current value Ig of the self-feeding path is much larger than the current value Ig of the other feeding paths. It displays that it is in contact and specifies the contact electric circuit.

  As described above, according to the present invention, the normal insulation state is monitored when there is no contact, and the insulation monitoring means that has stopped the calculation function at the same time that the contact between the ground phase and the ground is generated has the insulation impedance value. Since the current value converted into the current value is displayed, it is possible to determine the degree of incompatibility based on the display value, and it is possible to specify the incompatible power supply path between the ground phase and the ground by the display.

  In addition, when the voltage of the insulation monitoring signal drops below a predetermined value, the contact state is not displayed immediately, but the magnitude of the Ig value (current value obtained by converting the insulation impedance value into a current value), zero-phase current and It is possible to increase the degree of the determination of incompatibility by determining the state of incompatibility by comparing the above or other Igs.

  In this way, the determination of incompatibility is automated, and when it exceeds a preset Ig value or an Ig value that is arbitrarily set by the user, it is determined that incompatibility has occurred, and a “Consultation, Hassey” display or alarm is immediately issued and immediately issued Can take the measures. For this reason, the time required to specify the conventional mixed power feeding path can be greatly shortened.

  From the above, in addition to the function of monitoring the insulation state at all times, the function of constantly monitoring the contact between the ground phase and earth is added. Current flows, an alarm is issued, and it is possible to detect miswiring between the ground phase and non-ground phase of the three-phase outlet.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 shows a display example when there is no contact between the ground phase and the earth of the present invention, and FIG. 3 shows a display example after occurrence of contact between the ground phase and the ground. In the figure, 1-1, 1-2, 1-3 are transformers of each power station, and F1, F2, F3 are monitored electric circuits on the secondary side of the transformers 1-1, 1-2, 1-3. A certain power feeding path is shown, and grounding in each power feeding path is B-type grounded by a common ground line Ec through ground lines E1, E2, and E3. Reference numeral 3 denotes a monitoring signal generating means for generating a voltage of an insulation monitoring signal which is a reference of a low frequency (for example, 20 Hz) and a low voltage (for example, 10 V) different from the frequency of the power supply path, and a current transformer 4 for superposition. An insulation monitoring signal is superimposed on the common ground line Ec via Reference numerals 5-1 5-2, and 5-3 denote insulation monitoring means provided in the power supply paths F1, F2, and F3. The insulation monitoring signals superimposed on the common ground line Ec are transmitted to the ground lines E1, E2, and E3. It detects via each zero phase current transformer 6-1, 6-2, 6-3 provided in. Each insulation monitoring means 5-1, 5-2, 5-3 has a calculation function shown in FIG. 2 in addition to the conventional function of calculating the resistance component current. That is, FIG. 2 shows a flowchart of the calculation method. In the first and second steps S1 and S2, a voltage component and a current component of an insulation monitoring signal (abbreviated as a monitoring signal in the drawing) are input, and in step S3, the monitoring signal is input. The presence or absence of a decrease in voltage is determined. When there is no voltage drop, in step S4, the insulation resistance value between the electric circuit and the ground is calculated from the voltage and current components of the monitoring signal, and in step S5, the resistance component current value Igr is obtained from this resistance value. The component current value Igr is displayed on the display means 2-1, 2-2, 2-3 in FIG. 1, and when the current value becomes larger than a predetermined value, an alarm is issued, etc. Monitor. The insulation state of the electric circuit is monitored based on the displayed current value Igr.

  When there is a drop in the voltage of the monitoring signal detected in step 3, it is automatically switched to the mixed contact display means Mi side, and in step S7, an insulation impedance value is calculated based on the current of the insulation monitoring signal. In step S8, the insulation impedance value is converted into a current (Ig) value, and in step S9, the current value Ig is displayed on the display means 2-1, 2-2, 2-3 as shown in FIG.

  FIG. 3 shows a case where the ground phase and the ground are mixed in the power supply path F3. When the ground phase is mixed with the ground, as shown by a thick arrow in FIG. 3, the ground phase-earth-common ground line Ec-ground line is shown. A large current flows through E3. At this time, the voltage component of the insulation monitoring signal superimposed from the superimposing transformer 3 decreases from a dotted line to a solid line as indicated by the transformer 4. The insulation monitoring means 5-3 detects this voltage drop and displays “Ig: 999 mA” in which the insulation impedance value is converted into a current value in step S8, and the insulation monitoring means 5-2 and 5-3 operate similarly. However, since there is no contact, the current value Ig which is not so large as 7 mA and 5 mA is displayed as shown in the figure. Therefore, the contact electric circuit can be immediately determined, and the degree of contact can be determined from the displayed current value.

FIG. 4 shows another display example (second embodiment of the contact display means). Since a large current flows in the power supply path in contact with the ground of the ground phase, only the insulation monitoring means that detects this current [Consultation Hassey ] (Or alarm) so that the mixed power feeding path can be specified. That is, the current value (Ig) obtained by converting the insulation impedance value into a current value in step S8 in FIG. 2 is determined in step 9-1 in FIG. 5, and if it does not reach the preset set value, in step 10 “---” is displayed. If it is larger, “Consultation Hassey” is displayed in Step 11 and an alarm is issued.
FIG. 6 shows a third embodiment of the mixed touch display means Mi. After the current value Ig becomes equal to or higher than the set value, a zero-phase current I0 according to the frequency of the feed path is input in step S21 in order to further improve the accuracy. In step 22, the zero-phase current I 0 is compared with the current value Ig, and when the difference current value becomes larger than a preset value, “consultation” is displayed in step 23. is there. The insulation state monitoring device generally has an insulation monitoring unit and a leakage detection unit, and the zero-phase current transformer 6 detects the current of the insulation monitoring signal and the zero-phase current according to the frequency of the feeding path separately by a filter. A zero-phase current is used.

  The zero-phase current I0 due to the frequency of the feed path is a current that flows due to the deterioration of the insulation resistance between the non-grounded phase and the ground. When this zero-phase current increases, the previous insulation impedance value is converted into a current value. The current value Ig also increases. Whether or not the increase in the current value Ig is caused by the increase in the zero-phase current I0 can be determined by comparing the two and obtaining the difference therebetween, thereby preventing the display of incompatibility.

FIG. 7 shows a fourth embodiment of the tactile display means Mi. In the case where the insulation monitoring signal of each power supply path can be managed in one place as in the centralized monitoring control, in step 31, all other power supply paths are displayed. When current Ig is input, it is determined in step 32 whether the Ig value of the self-feeding path is very large compared to the Ig values of other feeding paths, and if it is very large (when it is greater than a preset set value) In step 33, “consumption” is displayed.
For each of the above set values, the current value Ig value is set in advance to automate the determination of the degree of contact, or is arbitrarily set by the user, and prompt response is encouraged when the degree of contact exceeds the set value. To do.

  Although the present invention has been described in detail only for the specific examples described above, it is obvious to those skilled in the art that various changes and modifications are possible within the scope of the technical idea of the present invention. Such variations and modifications are naturally within the scope of the claims.

The example of a display at the time of normal in this Embodiment. The flowchart of the example of a calculation in this Embodiment. The example of a display at the time of the contact occurrence of the ground phase and earth in this Embodiment. The example of a display at the time of the generation | occurrence | production of the contact of the ground phase and earth in other embodiment of this Embodiment. The flowchart in 2nd Embodiment of a touch display means. The flowchart in 3rd Embodiment of a touch display means. The flowchart in 4th Embodiment of a mixed display means. Explanatory drawing of a general insulation state monitoring apparatus. The vector diagram for description of a general insulation state monitoring apparatus. Explanatory drawing of the insulation monitoring in a common grounding system.

Explanation of symbols

1-1, 1-2, 1-3 ... Transformer 2-1, 2-2, 2-3 ... Display means 3 ... Monitoring signal generating means 4 ... Transformer 5-1, 5-2, 5-3 ... Insulation monitoring means 6-1, 6-2, 6-3 ... Zero-phase current transformer Ec ... Common ground line Mi ... Mixed contact display means

Claims (5)

Insulation monitoring signal generation for grounding Class B with a common grounding wire that shares the secondary grounding wires of transformers in a plurality of power stations, and generating an insulation monitoring signal having a low frequency different from the frequency of the power feeding path on this common grounding wire Means for superimposing the insulation monitoring signal on the common ground line via a superposition transformer, and at each power station, an insulation monitoring means for detecting the insulation monitoring signal via a zero-phase current transformer is provided. The insulation monitoring means inputs the voltage and current of the detected insulation monitoring signal, calculates the resistance component current value from the input voltage and current, and the voltage of the insulation monitoring signal is normal or falls below a predetermined value. and has a mixed contact display means to function and displays the mixed contact state to have one of the determination, isolation when the voltage of the monitor signal is determined normal, the voltage component and a current component from the resistance component current value of an input insulation monitoring signal Igr look, this current Displayed on the display means to monitor the insulation state of the electric path by the magnitude of the current value, when the voltage of the ground phase is ground and mixed contact to the insulation monitoring signal is determined it falls lower than a predetermined value, the detected insulation monitoring signal Is automatically switched to the incompatibility display means side, and the intrusion display means calculates an insulation impedance value based on the current component of the insulation monitoring signal, converts the insulation impedance value into a current value Ig, and increases the current value Ig. An insulation state monitoring apparatus characterized in that the mixed state is displayed on the display means based on the above. The display of the contact state by the contact display means according to claim 1 displays the current value Ig obtained by converting the insulation impedance value into a current value on the display means so that the contact electric circuit can be discriminated by the magnitude of the displayed current value . The insulation state monitoring apparatus according to claim 1. The cross-contact display means according to claim 1 calculates an insulation impedance value based on a current component of the insulation monitoring signal when it is determined that the voltage of the insulation monitoring signal falls below a set value, and the impedance value is calculated as a current value. in terms determine the magnitude of the current Ig converted to, is characterized in that so as to identify incompatible path displayed on the display means that you are looking incompatible when larger than a preset set value The insulation state monitoring apparatus according to claim 1. The cross-contact display means according to claim 1 calculates an insulation impedance value based on a current component of the insulation monitoring signal when it is determined that the voltage of the insulation monitoring signal falls below a set value, and the impedance value is calculated as a current value. The magnitude of the converted current value Ig is determined, and when it is larger than the preset set value, the zero-phase current I0 is input according to the frequency of the feeding path, and the zero-phase current I0 and the insulation impedance value are converted into the current value. Compared with the current value Ig converted to, and when the current value of the difference exceeds a preset set value, it is displayed on the display means that it is in contact, and the contact electric circuit is specified. The insulation state monitoring device according to claim 1. The cross-contact display means according to claim 1 calculates an insulation impedance value based on a current component of the insulation monitoring signal when it is determined that the voltage of the insulation monitoring signal falls below a set value, and the impedance value is calculated as a current value. The magnitude of the converted current value Ig is determined, and when it is larger than a preset set value, the current value Ig obtained by converting the insulation impedance value of each power supply path grounded by the common ground line into a current value is obtained. It is determined whether or not the current value Ig of the self-feeding path is very large relative to the current value Ig of the other feeding path, and the display means that the current is in contact when a current larger than a preset value flows. view and insulation state monitoring apparatus according to claim 1, characterized in that so as to identify incompatible path.

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