Patent Application
20240258788
The present invention relates to a discharge detection system for detecting discharge occurred by an accident, such as tracking, a short circuit, and disconnection.
Japanese Patent Application Kokai Publication No. 2020-25460 (Patent Document 1) discloses a discharge detection structure built in a distribution board. The distribution board includes a main breaker, a plurality of branch breakers, and a bus to electrically connect them. Each circuit of the branch breakers has a built-in discharge detection structure. Each branch breaker has a secondary side electrically connected to, for example, a branch circuit, such as indoor wiring. To each branch circuit, a load is electrically connected. The load means, for example, a device operating by consuming electric power, such as a lighting fixture, a display, an air conditioner, and a refrigerator. When an accident, such as tracking, a short circuit, disconnection, and current leakage, occurs in the branch circuit or the load, discharge takes place between electric wires or between electrodes. When discharge occurs, a noise is superimposed on the voltage or current in the branch circuit. The discharge detection structure detects noises in a high frequency band superimposed on the voltage or current by a high pass filter and determines that discharge has occurred if the noise level is a threshold or more.
A noise associated with discharge (hereinafter, referred to as a “discharge noise”) has an excessive level. Accordingly, as illustrated in
The present invention has been made in view of the above problems, and it is an object thereof to provide a discharge detection system capable of distinguishing a discharge noise from a propagation noise without adding a low pass filter to interrupt such a propagation noise.
The discharge detection system of the present invention allows a discharge noise to be distinguished from a propagation noise without adding a low pass filter to interrupt such a propagation noise.
A discharge detector according to an embodiment of the present invention is described below with reference to the drawings.
An accident, such as tracking, a short circuit, and disconnection, may occur in the branch circuits and the loads. The discharge detection system in the present embodiment detects discharge occurred due to an accident, such as tracking, a short circuit, and disconnection. When discharge occurs, a discharge noise at an excessive level is superimposed on the voltage or current in the branch circuit. The discharge detection system determines whether discharge has occurred based on a duration time of the noise at the level of a threshold or more. The discharge detection system also specifies the discharge noise by eliminating propagation noises from the subject of the determination if a plurality of noises at levels of the threshold or more are detected.
As illustrated in
The filter circuit 32 of each subunit 3 is configured by, for example, connecting a capacitor and a resistor, not shown, in parallel to the branch circuit. The filter circuit 32 removes the utility frequency and passes noises in a predetermined frequency range. In the present embodiment, the noise means a voltage and is output from both ends of the resistor constituting the filter circuit 32. The amplifier 31 amplifies the level of the noise passed through the filter circuit 32 and outputs the noise to the processor 50.
The processor 50 detects occurrence of discharge based on the noise level amplified by the amplifier 31. The determination mechanism 52 determines whether discharge has occurred based on the duration time of the noise at the level of the threshold or more. In addition, if a plurality of noises at levels of the threshold or more are detected, the determination mechanism 52 specifies the discharge noise by eliminating propagation noises from these noises. The arithmetic mechanism 55 calculates values for the determination by the determination mechanism 52. If a plurality of noises at levels of the threshold or more are detected, the reset mechanism 51 changes the value of the setting of the amplification factor (multiple) of the amplifier 31. All of the reset mechanism 51, the determination mechanism 52, and the arithmetic mechanism 55 are programs to cause the processor 50 to execute predetermined process.
The processor 50 is electrically connected to the main breaker 11 and each branch breaker 12. The processor 50 is capable of interrupting the main breaker 11 and/or the branch breakers 12 by outputting a signal if detecting discharge. The power circuit 54 is electrically connected to the secondary side of the main breaker 11 to supply the electric power to the main unit 5. The power supplied to the main unit 5 is further supplied to each subunit 3.
A description is then given to process for specifying a discharge noise executed by the processor 50 of the main unit 5. As described above, the determination mechanism 52 of the processor 50 determines whether discharge has occurred based on the duration time of the noise at the level of the threshold or more. However, as illustrated in
When the amplification factor of each amplifier 31 having output the noise at the level of the threshold or more is reduced, the processor 50 is capable of specifying the noise with the least reduced level as the discharge noise.
In the three waveform diagrams of
As illustrated in
As described above, the processor 50 is capable of specifying which noise is the discharge noise by reducing the amplification factor of the amplifier 31 corresponding to each of the loads 8a through 8h to compare the reduced amount of the level of the noise output from each amplifier 31. For example, the processor 50 may specify which noise is the discharge noise by reducing the amplification factor of the two amplifiers 31 corresponding to the loads 8a and 8b outputting the noises at the levels of the threshold or more. As indicated by a broken line in
The processor 50 then determines that discharge has occurred when the duration time of the discharge noise reaches a preset determination time (e.g., 500 ms) or more. Based on the result of the determination, the processor 50 detects occurrence of discharge. The processor 50 having detected the occurrence of discharge executes, for example, process for interrupting the branch breaker 12 to which the load 8a is electrically connected, process for issuing an alarm, and the like. Moreover, the processor 50 is also capable of reporting that discharge has occurred in the branch circuit to which the subunit 3 corresponding to the load 8a is electrically connected, that is, the source of discharge.
The processor 50 is capable of specifying the noise at the highest level as the discharge noise when the amplification factor of each of the plurality of amplifiers 31 outputting the noises at the levels of the threshold or more is reduced to the same value.
For example, as indicated by a broken line in
The processor 50 then determines that discharge has occurred when the duration time of the discharge noise reaches a preset determination time (e.g., 500 ms) or more. Based on the result of the determination, the processor 50 detects occurrence of discharge. The processor 50 having detected the occurrence of discharge executes, for example, process for interrupting the branch breaker 12 to which the load 8a is electrically connected, process for issuing an alarm, and the like. Moreover, the processor 50 is also capable of reporting that discharge has occurred in the branch circuit to which the subunit 3 corresponding to the load 8a is electrically connected, that is, the source of discharge.
In the process of reducing the amplification factor of each of the plurality of amplifiers 31, the processor 50 may reduce the amplification factor of each amplifier 31 stepwise at each predetermined time to have the same value.
For example, as illustrated in the three waveform diagrams of
The processor 50 may calculate a total value or average value of the noise level amplified with each amplification factor of 20 times, 10 times, 5 times, and 2 times and compare the level of the noise output from the amplifier 31 corresponding to each of the loads 8a through 8h. In this case, the processor 50 determines that the noise having the largest total value or average value is the discharge noise. The calculation and comparison of the total value or average value of the noise level allow reduction in the number of determinations for specifying the discharge noise, causing reduction in the time until specifying the discharge noise. As a result, it becomes possible to detect discharge ending in a relatively short period of time.
For example, as illustrated in the three waveform diagrams of
In the embodiment illustrated in
The above process of reducing the amplification factor of the amplifiers 31 stepwise at each predetermined time and measuring the noise level may be executed only on the two or more amplifiers 31 outputting the noises at the levels of the threshold or more. As another example, the process may be executed on all the amplifiers 31 in the timing before the processor 50 detects the noises at the levels of the threshold or more. Moreover, the maximum value of the amplification factor of the amplifiers 31 may be a value reset in a learning mode described later.
The discharge detection system is intended to detect discharge occurred by an accident, such as tracking, a short circuit, and disconnection. However, some of the loads 8a through 8h continuously generate the noises at the levels of the threshold or more set in the processor 50. For example, fluorescent lamps sometimes continuously generate noises at levels more than the threshold for a while after being turned on. Thus, discharge detection systems turn out to make an erroneous determination that discharge has occurred due to a noise generated by normal operation of a load.
For this reason, as the discharge detection system illustrated in
If a noise is detected at the level of the threshold or more due to normal operation of the loads 8a through 8h, the learning mode is executed to reset the value of the amplification factor of the amplifiers 31 corresponding to the loads 8a through 8h. The two waveform diagrams in
The processor 50 executes the learning mode based on a signal output from an operation section, such as a switch, a button, and a touch screen, not shown. The processor 50 in the learning mode samples a noise at the first threshold or more output from each of the amplifiers 31 corresponding to the loads 8a through 8h. The processor 50 executes the process of reducing the amplification factor of any of the amplifiers 31 if the level of the noise output from the amplifiers 31 is the first threshold or more. For example, as illustrated in
The processor 50 then compares the level of the noise output from the amplifier 31 and having the reduced amplification factor with a second threshold. The second threshold is a value smaller than the first threshold and is set in the reset mechanism 51. The second threshold is preferably set to a value that cannot exceed the noise level of any of the loads 8a through 8h. If the noise level is the second threshold or more, the processor 50 reduces the amplification factor of the amplifier 31 again and compares the noise level with the second threshold. Meanwhile, if the noise level is less than the second threshold, the processor 50 terminates the process of reducing the amplification factor of the amplifier 31. Due to the above-described process of resetting the amplification factor, the noise levels of the loads 8a and 8b illustrated in
In the learning mode, the learning period is set for sampling the noises at the levels of the threshold or more by the processor 50. The length of the learning period may be set in, for example, hours, days, weeks, or months. The learning period may also be set by combining two or more of hours, days, weeks, and months. For example, for the discharge detection system to be installed in indoor wiring of a fully automated factory, the learning period is preferably set in a day or a week. In particular, a learning period of a week allows calculation of the optimal value of the setting of the determination time by executing the sampling by the processor 50 on weekdays and holidays and sampling noises from various devices operating in the factory without omission.
For example, the learning period may be a combination of a day and hours. In this case, the processor 50 executes the process of sampling noises at levels more than the threshold for given hours (e.g., from 9:00 to 17:00) in a day. As another example, the learning period may be a combination of a week and hours. In this case, the processor 50 executes the sampling of noises at levels more than the threshold for given hours every day in the week. As still another example, the learning period may be a combination of a month, weeks, days, and hours. In this case, the processor 50 executes the sampling of noises at levels more than the threshold for given hours on given days every week in the month.
It should be noted that the learning mode is initiated by manually operating the operation section, not shown. For example, if the learning period is set in a length of hours (e.g., 1 hour), the processor 50 immediately executes the sampling of noises at levels more than the threshold based on the signal from the operation section. As another example, if a start time and an end time are set for the learning period, the processor 50 executes the sampling of noises at levels more than the threshold at a preset start time (e.g., 9:00) based on the signal from the operation section.
The operation section for causing the processor 50 to execute the learning mode has a configuration that is not particularly limited and may be, for example, a simple switch or button. The operation section may also be configured with a plurality of switches or buttons. In this case, a function of initializing the reset value of the amplification factor of the amplifiers 31 to the initial values of the settings before shipment from the factory may be assigned to any of the plurality of switches or buttons. Moreover, the operation section may be configured with a touch screen to display images of such a plurality of switches or buttons.
In the learning mode, the processor 50 does not determine occurrence of discharge by comparing the duration time of the noise with the determination time. In the learning mode, an upper limit is thus set on the duration time of the noise measured by the processor 50. The processor 50 determines that discharge has occurred if the value of the duration time of the noise at the level of the threshold or more exceeds the preset upper limit. Based on the result of the determination, the processor 50 detects occurrence of discharge. The processor 50 having detected the occurrence of discharge executes, for example, process for interrupting the branch breaker 12 to which the load 8a or 8b is electrically connected, process for issuing an alarm, and the like.
The discharge detection system of the present invention is not limited to the embodiment described above. For example, in the embodiment described above, the processor 50 determines whether discharge has occurred based on the noise superimposed on the voltage. However, the processor 50 is also capable of determining whether discharge has occurred based on a noise superimposed on the current. For example, it is possible to detect a noise of the threshold or more superimposed on the current by converting power of an alternating current, which is the utility power, to a direct current by a CT (current transformer).
For example, the plurality of amplifiers 31 may be configured to be built in the main unit 5, not in the subunits 3. As another example, the subunits 3 are not limited to the configuration in the present embodiment where they are connected to the secondary side of the branch breakers 12 in series. For example, the subunits 3 may be connected to the primary side of the branch breakers 12 in series or may be connected to either one of the primary side or the secondary side of the branch breakers 12 in parallel.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-133523 | Aug 2020 | JP | national |
| 2021-064554 | Apr 2021 | JP | national |
This application is the United States national phase of International Patent Application No. PCT/JP2021/028686 filed Aug. 3, 2021, and claims priority to Japanese Patent Application No. 2020-133523 filed Aug. 6, 2020, and Japanese Patent Application No. 2021-064554 filed Apr. 6, 2021, the disclosures of which are hereby incorporated by reference in their entireties.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/028686 | 8/3/2021 | WO |
