JP2007285929A - Insulating monitoring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure precisely a leakage current from each feeder which is a measuring object with a simple constitution. <P>SOLUTION: This device has the first leakage current detection device 3 for detecting always each leakage current from a plurality of banks B, the second leakage current detection device 5 for detecting each leakage current from each feeder F branched from one bank in each bank B among a plurality of feeders F branched respectively from each bank B, a switching means for switching a detection object by the second leakage current detection device 5, and a control means for controlling the switching means so that a leakage current from each feeder F branched from a bank B wherein a leakage current value detected by first leakage current detection device 3 exceeds a prescribed threshold is detected by the second leakage current detection device 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an insulation monitoring apparatus that manages distribution lines and electrical circuit insulation for electrical security operations, and in particular, includes a plurality of banks and a plurality of feeders branched from these banks. The present invention relates to a device that detects leakage current in the entire power receiving facility.

  Conventionally, as an insulation monitoring device (also referred to as a “ground fault relay”) for monitoring insulation between a circuit and a ground (also referred to as “ground insulation resistance”), for example, one employing an Io method or an Igr method is known. Yes.

  In the conventional monitoring device, ZCT (Zero Phase Current Transformer) is installed in each of a plurality of feeders (distribution lines; electric circuit), and each installed ZCT is sequentially switched, and the leakage current of each of the feeders The thing of the structure which monitors is known (for example, refer patent document 1).

In addition, as an insulation monitoring device of a method not adopting the switching, for example, in order to detect the leakage current of each of a plurality of banks (buses; electric circuit) and the leakage current of a plurality of feeders branched from each of the banks A configuration is adopted in which a ZCT is installed in each bank and each feeder and the leakage current of each bank and each feeder is detected.
Japanese Utility Model Publication No. 61-182857

  By the way, in the conventional insulation monitoring apparatus described in Patent Document 1, since the feeders to be detected (measurement targets) are sequentially switched, there is a problem that the leakage current of each feeder may not be measured.

  The adverse effect of the above problem is more so-called intermittent than the case in which current starts to leak from scratches and deteriorated parts of the cable sheath, etc., and the leakage current increases due to deterioration caused by the heat generated by the leakage current (case due to deterioration). The case with a solitary earth fault becomes more prominent.

  That is, in the case of deterioration or the like, leakage current is continuously generated. On the other hand, intermittent solitary ground faults can cause insulation breakdown to occur at once when moisture penetrates into an insulator such as a cover in the form of a tree, but then the insulation may recover. In many cases, it only occurs. Therefore, a feeder in which an intermittent solitary ground fault is detected can be detected if a leakage current has occurred when this feeder becomes a measurement target, but a feeder in which an intermittent solitary ground fault occurs is a measurement target. If the leakage current does not occur at the time of occurrence and the leakage current is generated only when it is not the measurement target, it is impossible to detect the leakage current at the feeder in which the intermittent arc fault occurs.

  And all the feeders may generate a false report that there is no abnormality (no leakage). In addition, the above problem is more remarkable in the Igr method that requires more time for measurement than in the Io method.

  Therefore, an insulation monitoring device that can always detect the leakage currents of all feeders can be considered, but there is a problem in that the configuration of the insulation monitoring device becomes complicated.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an insulation monitoring device that can accurately measure the leakage current of each feeder to be measured with a simple configuration.

  The invention according to claim 1 is a first leakage current detection device that constantly detects a leakage current of each of a plurality of banks, and a plurality of feeders branched from each of the banks. A second leakage current detecting device for detecting a leakage current of each feeder branched from one bank; a switching means for switching a detection target by the second leakage current detecting device; and the first leakage current detection. When there is a bank in which the leakage current value detected by the device exceeds a predetermined threshold, the second leakage current detection device detects the leakage current of each feeder branched from the bank exceeding the threshold. And an insulation monitoring device having control means for controlling the switching means.

  According to a second aspect of the present invention, in the insulation monitoring device according to the first aspect, each of the leakage current detection devices is an insulation monitoring device that is a device that detects a leakage current by an Igr method.

  According to a third aspect of the present invention, in the insulation monitoring apparatus according to the first or second aspect, each of the control means is a detection target of the second leakage current detection apparatus by switching by the switching means. The leakage current threshold value in the feeder is notified to the second leakage current detection device, and the second leakage current detection device is an insulation monitoring device that detects the leakage current state of each feeder based on the notification. is there.

  According to a fourth aspect of the present invention, in the insulation monitoring device according to any one of the first to third aspects, the control means has a predetermined leakage current value detected by the first leakage current detection device. When there is no bank exceeding the threshold value, the feeders in the bank whose leakage current value detected by the first leakage current detection device is close to a predetermined threshold value are set as detection targets of the second leakage current detection device. And an insulation monitoring device for controlling the switching means.

  According to the present invention, it is possible to accurately measure the leakage current of each feeder to be measured with a simple configuration.

  FIG. 1 is a block diagram showing a schematic configuration of an insulation monitoring apparatus 1 according to an embodiment of the present invention.

  The insulation monitoring device 1 is a device that measures and monitors leakage (leakage current) from a plurality of banks (buses; electric circuits) B and a plurality of feeders (distribution lines; electric circuits) F branched from the banks B. Yes, a first leakage current detection device 3 is provided. In FIG. 1, the number of banks B is eight (banks B1 to B8), and eight feeders are branched from each bank as an example. More specifically, eight feeders F11 to F18 are branched from the first bank B1, and eight feeders F21 to F28 are branched from the second bank B2. As an example, eight feeders F81 to F88 are branched from the eye bank B8. Each feeder F is connected to a load such as a motor or lighting.

  The leakage current detection device 3 of the insulation monitoring device 1 can always detect the leakage current of each of the plurality of banks B. That is, the leakage current detection device 3 includes a device main body 4, and the device main body 4 is provided with, for example, eight monitoring units 41 to 48. Each of the banks B1 to B8 is provided with zero-phase current transformers (ZCT) Z1 to Z8. The detection result of each zero-phase current transformer Z (Z1 to Z8) is sent to each monitoring unit 41 to 48 via a signal line (for example, the detection result by the zero-phase current transformer Z1 in the bank B1 is the monitoring unit 41). The leakage current of each bank B (B1 to B8) is always detected in a live state (monitoring the ground insulation state).

  In addition, the insulation monitoring device 1 is provided with a leakage current detection device 5, and the leakage current detection device 5 is a plurality of feeders F branched from each of the banks B. The leakage current of each feeder F branched from one bank can be detected.

  That is, the leakage current detection device 5 includes a device main body 6, and the device main body 6 is provided with, for example, eight monitoring units 61 to 68. In addition, each of the feeders F (F11 to F18, F21 to F28,..., F81 to F88) has zero phase current transformers Z (Z11 to Z18, Z21 to Z28,..., Z81 to Z88). ) Is provided. The detection result of each zero-phase current transformer Z is sent to each monitoring unit 61-68 via a signal line, and the leakage current of each feeder F is always detected.

  In addition, the insulation monitoring device 1 is provided with changeover switches SW1 to SW8 which are examples of switching means for switching a detection target by the leakage current detection device 5. By closing (connecting) only one of the change-over switches SW1 to SW8, the measurement target of the leakage current detection device 5 can be changed.

  More specifically, the changeover switch SW1 is composed of eight switches SW11 to SW18, and the other switches SW2 to SW8 are similarly configured. Then, for example, by closing the switches SW11 to SW18 of the changeover switch SW1 and opening all of the other changeover switches SW2 to SW8, each of the zero-phase current transformers Z11 to Z18 is monitored by the leakage current detection device 5. The leakage currents of the feeders F11 to F18 connected to the units 61 to 68 and branching from the bank B1 can be measured simultaneously.

  Further, the insulation monitoring device 1 is provided with a control device (CT switching controller) 7. The control device 7 includes an LCD display 71 that is an example of output means, a contact output unit 75, a communication port 77, an operation switch 73 that is an example of input means, and a communication port 77. In addition, the control device 7 receives a signal from the leakage current detection device 3 via, for example, RS-485, switches the changeover switches SW1 to SW8 based on the received signal, and is measured by the leakage current detection device 5. The feeder F is controlled so as to determine the feeder F.

  That is, when there is a bank B in which the leakage current value detected by the leakage current detection device 3 exceeds a predetermined threshold (for example, when the bank B2 exceeds the threshold), the bank B2 is branched from the bank B2 exceeding this threshold. Control is performed such that only the changeover switch SW2 (each switch SW21 to SW28) is closed and the other changeover switches SW1, SW3 to SW8 are opened so that the leakage current detection device 5 detects the leakage current of each feeder F21 to F28. It is supposed to be.

  And the feeder F in which the value of the leakage current exceeded the threshold among each feeder F21-F28 used as the measuring object of the leakage current detection apparatus 5 is specified.

  The results measured in this way are displayed on the LCD display 71 as an example of the output means, or are output to the central monitoring panel CW via the contact output unit 75 and the communication port 77. Yes.

  By the way, each of the leakage current detection devices 3 and 5 is configured to detect the leakage current not by the Io method but by the Igr method, for example. Here, the Io method means that a ground fault current (leakage current) actually flowing outside the system at 50 Hz / 60 Hz (commercial frequency) is obtained by letting a wire to be measured pass through a zero-phase current transformer all at once. This is a detection method, and the Igr method electromagnetically couples an AC signal (AC voltage) of a frequency different from the commercial frequency (for example, a frequency of about 20 Hz) to the measurement target wire to the ground wire of the class B grounding work. A ground fault current that is a leakage current flowing between the electric circuit and the earth is detected by a ZCT (zero phase current transformer; also indicated as “CT”) provided on the ground line, and the detected signal This is a system that extracts the current component due to the ground insulation resistance component from the inside (detects the effective component), performs various calculations and monitors the true insulation resistance, and electrical equipment where many OA and FA devices are used Then, leakage current compared to Io method There are those that can be detected with accuracy. The details of the Igr method are described in more detail in, for example, Japanese Patent Laid-Open No. 9-318684.

  Further, the control device 7 notifies the leakage current detection device 5 of the leakage current threshold value of each feeder F to be detected by the leakage current detection device 5 and the electric circuit voltage of each feeder F by switching by the switching means. It is like that. The leakage current detection device 5 detects the leakage current state of each feeder F based on the notification.

  In addition, the threshold value of the leakage current in each feeder F and the electric circuit voltage of each feeder F are input to the control device 7 by a personal computer PC connected to the operation switch 73 and the communication port 77 which are examples of the input means, for example, via RS-232C. And stored in a storage device (not shown) of the control device 7. And it is suitably sent to the leakage current detection device 5.

  Next, the operation of the insulation monitoring device 1 will be described.

  FIG. 2 is a flowchart showing the operation of the insulation monitoring apparatus 1.

  First, each bank B and each feeder F are connected to a commercial power source, and when a load is connected to each feeder F, it is assumed that this load is operating or is at rest.

  Under the control of the control device 7, the leakage current detection device 3 constantly monitors the leakage current of each bank B (S1), and determines whether there is a bank B whose leakage current value exceeds the threshold (S3). . In addition, although the threshold value of the leakage current in each bank B is input and stored in advance in the leakage current detection device 3, it is input by the input means of the control device 7 as in the case of each feeder F, The leakage current detection device 3 may be notified.

  When there is a bank B in which the value of the leakage current exceeds the threshold value, the changeover switches SW1 to SW8 are switched so as to detect the leakage current of each feeder F branched from the bank B exceeding the threshold value ( S5), monitoring (measuring) the leakage current of each feeder F that is the measurement target in the leakage current detection device 5 (S7). For example, when the leakage current in the bank B8 exceeds the threshold value, the switches SW81 to SW88 are closed, the other switches SW11 to SW18,..., SW71 to SW78 are opened, and the feeders F81 to F88 are set as measurement targets. To do.

  Subsequently, it is determined whether or not there is a feeder F whose leakage current value exceeds the threshold among the feeders F to be measured (S9), and the feeder whose leakage current value exceeds the threshold. If F exists, a signal for identifying the feeder such as the feeder number is output to the central monitoring panel CW (S11).

  As described above, when the leakage current in the bank B8 exceeds the threshold value, the switches SW81 to SW88 can be closed simultaneously and collectively.

  According to the insulation monitoring device 1, the leakage current detection device 3 always detects the leakage current of each of the plurality of banks B, and there is a bank B in which the leakage current value detected by the leakage current detection device 3 exceeds a predetermined threshold. In this case, since the leakage current of each feeder F branched from the bank B exceeding the threshold value is detected by the leakage current detection device 5, the number of leakage current detection devices is smaller than that of the prior art, that is, with a simple configuration, The leakage current of the bank B and the feeder F can be accurately detected. Further, it is possible to easily detect an intermittent solitary ground fault in which a leakage current is generated only intermittently.

  For example, as shown in FIG. 1, when there are eight banks B and eight feeders F branching from each bank B, in order to accurately detect the leakage current of all the feeders F, If the conventional method without switching is adopted, an expensive monitoring unit (41 or the like) for at least 64 feeders is required. However, in the case of the insulation monitoring apparatus 1, a total of 16 for 8 banks and 8 feeders. There may be only one monitoring unit 41 to 48, 61 to 68.

  Moreover, according to the insulation monitoring apparatus 1, it is possible to detect the accurate leakage current (leakage current) of all the banks B and feeders F without causing a large time lag.

  That is, when the Io method is adopted, it takes only about 1 second to detect the leakage, but when the Igr method is adopted, the Io method is used to detect the leakage in order to perform the calculation of the effective component as described above. It takes about 10 seconds longer than the method, and the conventional method described in Patent Document 1 requires 80 seconds to detect the leakage of eight feeders. However, according to the insulation monitoring apparatus 1, the Igr method that can accurately detect the leakage current with high accuracy by adopting a configuration that closes the switches simultaneously and collectively is adopted. , Almost no time lag occurs.

  Further, according to the insulation monitoring device 1, the leakage current threshold value of each feeder F is notified to the leakage current detection device 5, and the state of leakage current of each feeder F is detected based on the notification. Even if the threshold values of the leakage current at F are different, the leakage current of each feeder F can be accurately detected.

  In the insulation monitoring device 1, even when there is no bank B whose leakage current value detected by the leakage current detection device 3 exceeds a predetermined threshold, the leakage current detection device 3 under the control of the control device 7. Each of the feeders F in the bank B in which the leakage current value detected in step S is close to a predetermined threshold value may be set as a detection target of the leakage current detection device 5.

  Thus, even if the value of the leakage current does not exceed the threshold value in each bank B, the value of the leakage current is set to the threshold value by setting each feeder F of the bank B whose leakage current value is close to the threshold value to be measured. Before exceeding, it is possible to know in advance the deterioration of the wiring of the feeder F, etc., which can be used for maintenance.

  Further, even if the leakage current value does not exceed the threshold value in each bank B, the leakage current value is a threshold value in some of the feeders F of the bank B whose leakage current value is close to the threshold value. However, in this case, it is possible to surely find the partial feeder F.

  When there is no bank B whose leakage current value detected by the leakage current detection device 3 exceeds a predetermined threshold, the detection target of the leakage current detection device 5 is simply switched sequentially under the control of the control device 7. Also good.

  In FIG. 1, the number of feeders F branching from each bank B may be different from each other, and the switching means is changed as appropriate so that the leakage current detection device 3 and the leakage current detection device 5 are You may make it also use.

  In addition, in the insulation monitoring device 1, the feeder F is branched from the bank B, and the leakage current in the two layers of the bank B and the feeder F is detected. By changing the leakage current detection device and the switching means as appropriate, The insulation monitoring device according to the present embodiment can also be applied when the wiring is further branched from each feeder F to have three or more layers.

It is a block diagram which shows schematic structure of the insulation monitoring apparatus which concerns on embodiment of this invention. It is a flowchart which shows operation | movement of an insulation monitoring apparatus.

Explanation of symbols

1 Insulation monitoring device 3, 5 Leakage current detection device 7 Control device B Bank F Feeder Z Zero-phase current transformer

Claims (4)

A first leakage current detection device that constantly detects the leakage current of each of the plurality of banks;
A second leakage current detection device that detects a leakage current of each of the feeders branched from one of the banks among the plurality of feeders branched from each of the banks;
Switching means for switching a detection target by the second leakage current detection device;
When there is a bank in which the leakage current value detected by the first leakage current detection device exceeds a predetermined threshold, the leakage current of each feeder branched from the bank exceeding the threshold is used as the second leakage current. Control means for controlling said switching means for detection by a detection device;
An insulation monitoring device comprising: The insulation monitoring device according to claim 1,
Each said leakage current detection apparatus is an apparatus which detects a leakage current by an Igr system, The insulation monitoring apparatus characterized by the above-mentioned. In the insulation monitoring device according to claim 1 or 2,
The control means notifies the second leakage current detection device of a leakage current threshold value in each feeder to be detected by the second leakage current detection device by switching by the switching means, and the second leakage current detection device. An insulation monitoring apparatus, wherein the leakage current detection apparatus detects a state of leakage current of each feeder based on the notification. In the insulation monitoring apparatus according to any one of claims 1 to 3,
When there is no bank in which the leakage current value detected by the first leakage current detection device exceeds a predetermined threshold, the control means detects the leakage current value detected by the first leakage current detection device as a predetermined threshold. The insulation monitoring device is characterized in that the switching means is controlled so that each feeder in a bank close to is a detection target of the second leakage current detection device.

Images