JP6327507B2 - Insulation monitoring device - Google Patents

Description

  The present invention relates to an insulation monitoring apparatus for monitoring insulation deterioration of an electric circuit having a plurality of branch circuits in a circuit configuration in which a secondary side electric circuit of a transformer is in a non-grounded state by a non-ground distribution system or a ground distribution system.

  In the non-grounded distribution system in which the secondary side of the transformer is ungrounded, a closed circuit is not formed even if the insulation resistance decreases in one phase. Therefore, since the supply of power can be ensured even in the case of one-phase ground insulation breakdown (ground fault), it is possible to prevent the entire secondary side electric circuit of the transformer from causing a power failure.

  Although this non-grounded distribution system can prevent a power failure of the entire secondary side electric circuit of the transformer even if the insulation is deteriorated in one phase, the insulation deterioration of the electric circuit cannot be removed. Furthermore, if the other phases are insulated and deteriorated in this state, the entire secondary side electric circuit of the transformer will be cut off. Therefore, an insulation monitoring device is installed to monitor the insulation deterioration of the electric circuit.

  As an insulation monitoring device for ungrounded electrical circuits, a device that can accurately measure the leakage current of each feeder of a distribution facility composed of a plurality of banks and a plurality of feeders branched from each bank. Yes (see Patent Document 1). In addition, as an insulation monitoring method for non-grounded electric circuits, there is one that can monitor which feeder of a plurality of feeders has deteriorated from the bus (see, for example, Patent Document 2).

JP 2007-285929 A JP 9-218237 A

  However, in Patent Documents 1 and 2, it is possible to monitor which feeder has undergone insulation degradation, but it is difficult to specify the location of insulation degradation. In order to identify the location where insulation deterioration has occurred in a live line state, for example, it is necessary to unplug each device from the outlet and check with which device the insulation monitoring device will not detect insulation deterioration. Also, if it is assumed that the insulation deterioration is due to the insulation deterioration of the wire, open the switches one by one and check which switch is opened when the insulation monitoring device will not detect the insulation deterioration However, the insulation deterioration point of the electric wire must be specified. Therefore, in order to protect the electric circuit and equipment and to ensure the safety and continuity of operation, it is required that the location of insulation deterioration can be specified in a live line state.

  An object of the present invention is to provide an insulation monitoring device that can identify an insulation deterioration point of an electric circuit having a plurality of branch circuits in a non-grounded state by a non-grounded distribution method or a grounded distribution method. is there.

In the insulation monitoring device of the present invention, a plurality of feeders are drawn from a branch distribution bus that branches from the nearest distribution bus on the secondary side of the transformer in a circuit configuration that is ungrounded by a non-ground distribution system or a ground distribution system. A DC current supply unit that is connected to the nearest distribution bus of an electric circuit having a plurality of branch circuits in the feeder and supplies an exploration current to the electric circuit in a live state when the electric circuit has insulation deterioration; and a branch of the branch circuit a current detector for detecting a probe current supplied from the direct current supply unit respectively provided on the downstream side of the point, the predetermined value is greater than exploration currents enter the probe current detected by said current detector An insulation state evaluation unit that identifies a location of insulation deterioration from the detected arrangement relationship of current detectors is provided.

  According to the present invention, a non-grounded distribution system or a grounded distribution system is used for the nearest distribution bus on the secondary side of a transformer in a circuit having a plurality of branch circuits on the secondary side of the transformer. Since the location of insulation deterioration is identified from the arrangement relationship of the current detectors that supply the exploration current in the line state and detect the exploration current greater than the predetermined value, set it to the non-ground state with the non-ground distribution method or the ground distribution method With this circuit configuration, it is possible to identify the location of insulation deterioration in an electric circuit having a plurality of branch circuits in a live state.

The systematic diagram which shows an example of the electric circuit of the non-grounding distribution system to which the insulation monitoring apparatus which concerns on 1st Embodiment of this invention is applied. The system diagram which simplified the system diagram of the electric circuit shown in FIG. Operation | movement explanatory drawing of the insulation monitoring apparatus which concerns on 1st Embodiment of this invention when insulation degradation exists in the terminal circuit of the electric circuit shown in FIG. Operation | movement explanatory drawing of the insulation monitoring apparatus which concerns on 1st Embodiment of this invention when there is insulation degradation in the middle of the electric circuit shown in FIG. Operation | movement explanatory drawing of the insulation monitoring apparatus which concerns on 1st Embodiment of this invention when insulation degradation exists in two places of the electrical circuit shown in FIG. The simplified systematic diagram which shows an example of the electric circuit of the non-grounding distribution system to which the insulation monitoring apparatus which concerns on 2nd Embodiment of this invention is applied. Operation | movement explanatory drawing of the insulation monitoring apparatus which concerns on 2nd Embodiment of this invention when there exists insulation degradation in the middle of the electric circuit shown in FIG. Operation | movement explanatory drawing of the insulation monitoring apparatus which concerns on 2nd Embodiment of this invention when insulation degradation exists in the branch distribution bus of the electrical circuit shown in FIG. Operation | movement explanatory drawing of the insulation monitoring apparatus which concerns on 2nd Embodiment of this invention which shows an example when insulation degradation exists in two places of the electrical circuit shown in FIG. Operation | movement explanatory drawing of the insulation monitoring apparatus which concerns on 2nd Embodiment of this invention when insulation degradation exists in the downstream of the connection point to the nearest distribution bus of the direct current supply part of the electric circuit shown in FIG. Operation | movement explanatory drawing of the insulation monitoring apparatus which concerns on 2nd Embodiment of this invention which shows another example when insulation degradation exists in two places of the electrical circuit shown in FIG. Operation | movement explanatory drawing of the insulation monitoring apparatus which concerns on 2nd Embodiment of this invention when insulation degradation exists in the upstream of the connection point to the nearest distribution bus of the direct current supply part of the electric circuit shown in FIG. Operation | movement explanatory drawing of the insulation monitoring apparatus which concerns on 2nd Embodiment of this invention which shows another example when insulation degradation exists in two places of the electrical circuit shown in FIG.

Hereinafter, a first embodiment of the present invention will be described. The present invention can be applied not only to the non-grounded power distribution method but also to a circuit configuration in a non-grounded state by the grounded power distribution method. In the following description, a case where the present invention is applied to the non-grounded power distribution method will be described.
FIG. 1 is a system diagram showing an example of an ungrounded power distribution system to which the insulation monitoring apparatus according to the first embodiment of the present invention is applied. The transformer 11 is provided with a contact prevention plate (not shown). This anti-contact plate protects the primary side high voltage from entering the secondary side (low voltage side) even if the insulation between the transformer primary coil (high voltage coil) and secondary coil (low voltage coil) is broken. To do. This constitutes a non-grounded power distribution system.

  In such an ungrounded distribution system, the voltage stepped down by the transformer 11 is supplied to the distribution bus 12. The distribution bus 12 includes a nearest distribution bus 12a closest to the secondary side of the transformer 11 and a branch distribution line 12b branched from the nearest distribution bus 12a. A plurality of feeders 13a to 13n are drawn out from the branch distribution bus 12b, and power is supplied to each of the feeders 13a to 13n via the branch distribution bus 12b. Each feeder 13a-13n has a plurality of branch circuits. A switch 14 is provided on the downstream side of the branch point of the secondary side electric circuit. The switch 14 is normally closed and is opened when the downstream side (load side) of the switch 14 is inspected.

  The insulation monitoring apparatus according to the first embodiment of the present invention includes a current detector 15 provided on the downstream side of the branch point of the branch circuit, that is, on the upstream side (transformer side) of each switch 14, It consists of a direct current supply unit 16 that supplies the exploration current Is to the secondary side electric circuit of the transformer 11 in a live line state, and an insulation state evaluation unit 17 that identifies the location of insulation degradation.

  The direct current supply unit 16 is connected to the closest distribution bus 12 a on the secondary side of the transformer 11. Then, a DC exploration current Is is supplied to the secondary side electric circuit of the transformer 11 in a live line state. The direct current supply unit 16 includes a direct current power source 18, a switch 19, and a resistor R0, and is grounded to the ground point A through the resistor R0. When the switch 19 of the DC current supply unit 16 is turned on, the DC power supply 18 is connected to the ground point A through the resistor R0. The switch 19 of the DC current supply unit 16 is normally on. The exploration current Is is a direct current that flows when the secondary side electric circuit of the transformer 11 is deteriorated in insulation, and the exploration current Is is zero when there is no portion of insulation deterioration.

  The current detector 15 is provided on the upstream side of each switch 14 (branch point of the branch circuit), and detects the exploration current Is supplied from the DC current supply unit 16. For example, the feeder 13a is provided with current detectors 15a1 to 15a11 on the upstream side of the switches 14a1 to 14a11, the feeder 13d is provided with current detectors 15d1 to 15d4 on the upstream side of the switches 14d1 to 14d4, and the feeder 13n. Are provided with current detectors 15n1 to 15n11 upstream of the switches 14n1 to 14n11.

  The other feeder 13 is similarly provided with a switch 14 and a current detector 15, but FIG. 1 shows the switches 14b1, 14c1, 14e1 and the current detectors 15b1, 15c1, 15e1, and other switches. The device 14 and the current detector 15 are not shown. The current detector 15 uses a highly sensitive measuring instrument {for example, an AC / DC clamp leaker (M700, M730) with a clamp type measuring instrument manufactured by Multi Instrument Co., Ltd.}.

  The current detector 15 may be provided on the upstream side corresponding to all the switches 14, but is not necessarily provided on the upstream side of all the switches 14. What is necessary is just to provide in the branch point of a branch circuit as needed according to the importance of a load or a branch circuit.

  The insulation state evaluation unit 17 inputs the detection value of the exploration current Is detected by each current detector 15. The detection value of each current detector 15 is input to the insulation state evaluation unit 17 through a signal line (not shown). Moreover, you may make it input into the insulation state evaluation part 17 by radio | wireless communication.

  The insulation state evaluation unit 17 determines the current detector 15 that has detected the exploration current Is larger than a predetermined value, and identifies the location of insulation deterioration from the arrangement relationship of these current detectors. For example, the current detector 15 that detects the exploration current Is greater than a predetermined value is output, and information for specifying the location of insulation deterioration is provided to the worker. Moreover, the location of insulation deterioration is specified from the arrangement relationship of the current detectors. Further, as necessary, when the current detector 15 detects the exploration current Is, the insulation state evaluation unit 17 obtains the insulation resistance R based on the magnitude of the exploration current Is, and determines the obtained insulation resistance R. The insulation state is evaluated by the size.

  The insulation resistance evaluation result obtained by the insulation state evaluation unit 17 and the information on the location of insulation deterioration may be stored in a storage device, or an alarm device, a display device, a printing device, communication, if necessary. You may make it output to output devices, such as an apparatus.

  FIG. 2 is a system diagram that simplifies the system diagram of the electric circuit shown in FIG. 1, and the feeder 13 shows the case of five feeders 13 a to 13 e, and the feeder 13 a to 13 e at the branching point. The branch circuit is not shown. Since the current detector 15 is provided on the downstream side of the branch point, the branch circuit is actually branched on the upstream side of each current detector, but the illustration of the branch circuit is omitted. The illustration of the switch 14 is also omitted. Hereinafter, description will be given based on the simplified system diagram shown in FIG.

  FIG. 3 is an operation explanatory diagram of the insulation monitoring apparatus according to the first embodiment of the present invention when there is insulation deterioration in the terminal circuit of the electric circuit shown in FIG. Now, it is assumed that the insulation resistance R1 is deteriorated at the point F1 of the terminal circuit of the feeder 13e. Then, since the switch 19 of the DC current supply unit 16 is in an ON state, the DC power supply 18 of the DC current supply unit 16, the grounding point A, the insulation deterioration point F1, the feeder 13e, the branch distribution bus 12b, the nearest distribution bus 12a, A closed circuit (hereinafter referred to as F1 closed circuit) of the DC power supply 18 of the DC current supply unit 16 is formed, and the search current Is1 flows from the DC power supply 18 of the DC current supply unit 16 in the direction indicated by the arrow in FIG. This exploration current Is1 flows from the downstream side (load side) to the upstream side (transformer side) when viewed from the transformer side, and is detected by the current detectors 15e4, 15e3, 15e2, and 15e1 of the feeder 13e.

  When the current detectors 15e4, 15e3, 15e2, and 15e1 detect the exploration current Is1, the insulation state evaluation unit 17 determines the exploration current Is1 detected by the current detectors 15e4, 15e3, 15e2, and 15e1 as a predetermined value. It is determined whether or not the value is larger than the predetermined value. Thereby, the worker can specify the location of insulation deterioration.

  Moreover, the insulation state evaluation part 17 specifies the location of insulation degradation from the arrangement | positioning relationship of the current detectors 15e4, 15e3, 15e2, and 15e1. That is, the insulation state evaluation unit 17 is downstream of the most downstream current detector 15e4 through which the search current Is1 flows among the current detectors 15e4, 15e3, 15e2, and 15e1 that have detected a search current greater than a predetermined value. It is judged that there is a place of insulation deterioration on the load side. This is because the exploration current Is1 that flows through the current detectors 15e3, 15e2, and 15e1 upstream of the current detector 15e4 flows due to the effect of insulation deterioration at a location downstream of the current detector 15e4.

  Further, the insulation state evaluation unit 17 evaluates the insulation resistance R1 at the insulation deterioration point F1 based on the magnitude of the exploration current Is1. In the F1 closed circuit at the insulation deterioration point F1, the search current Is1 detected by the current detectors 15e4, 15e3, 15e2, and 15e1 is input, and the insulation resistance R1 is calculated based on the magnitude of the search current Is1. . The search current Is1 detected by the current detectors 15e4, 15e3, 15e2, and 15e1 in the F1 closed circuit has the same value because there is no insulation deterioration point other than the insulation deterioration point F1.

  Assuming that the voltage of the DC power supply 18 of the DC current supply unit 16 is E, the following equation (1) is established. When the insulation resistance R1 is obtained from the equation (1), the insulation resistance R1 is expressed by the equation (2).

Is1 = E / (R0 + R1) (1)
R1 = (E / Is1) −R0 (2)
Since the voltage E of the DC power supply 18 and the resistance R0 of the DC current supply unit 16 are known, and the exploration current Is1 is a value detected by the current detectors 15e4, 15e3, 15e2, and 15e1, the insulation resistance is obtained from the equation (2). R1 can be determined. The insulation state evaluation unit 17 evaluates the insulation state based on the obtained magnitude of the insulation resistance R1.

  In this way, the insulation state evaluation unit 17 outputs information on the current detector 15 that has detected the exploration current Is greater than a predetermined value, and determines the location of insulation deterioration from the arrangement relationship of these current detectors 15. Identify and determine insulation resistance as needed. If there is insulation degradation at point F1 in FIG. 3, it is determined that insulation degradation has occurred at a location downstream of the most downstream current detector 15e4 through which the search current Is1 flows. Further, the insulation resistance R1 is obtained based on the magnitude of the search current Is1 detected by the current detectors 15e4, 15e3, 15e2, and 15e1.

  FIG. 4 is an operation explanatory diagram of the insulation monitoring apparatus according to the first embodiment of the present invention when insulation deterioration occurs in the middle of the electric circuit shown in FIG. Now, it is assumed that the insulation resistance R2 is deteriorated at the point F2 in the middle of the feeder 13e. Then, the DC power supply 18 of the DC current supply unit 16, the ground point A, the insulation degradation point F2, the feeder 13e, the branch distribution bus 12b, the nearest distribution bus 12a, and the closed circuit of the DC power supply 18 of the DC current supply unit 16 (F2 closed circuit). ) And the exploration current Is2 flows from the DC power source 18 of the DC current supply unit 16 in the direction indicated by the arrow in FIG. This exploration current Is2 is detected by the current detectors 15e2 and 15e1 of the feeder 13e.

  In the F2 closed circuit, the insulation state evaluation unit 17 determines whether the exploration current Is2 detected by the current detectors 15e2 and 15e1 is greater than a predetermined value when the exploration current Is2 is detected by the current detectors 15e2 and 15e1. If it is greater than a predetermined value, the information is output to the outside. Thereby, the worker can specify the location of insulation deterioration.

  Moreover, the insulation state evaluation part 17 specifies the location of insulation degradation from the arrangement | positioning relationship of the electric current detectors 15e2 and 15e1. That is, the insulation state evaluation unit 17 is the current detector 15e2, 15e1 that has detected the exploration current greater than a predetermined value on the load side downstream of the most downstream current detector 15e2 through which the exploration current Is1 flows. Judge that there is a place of insulation deterioration. In addition, since the current detectors 15e3 and 15e4 on the downstream side of the current detector 15e2 have not detected the exploration current Is2 that is larger than the predetermined value, the location of insulation deterioration is on the upstream side of the current detector 15e3. to decide.

  Further, the insulation state evaluation unit 17 evaluates the insulation resistance R2 at the insulation deterioration point F2 based on the magnitude of the exploration current Is2. Using the above equations (1) and (2), Is1 in the equation (1) is replaced with Is2 and R1 is replaced with R2, and the insulation resistance R2 is obtained. The insulation state is determined by the magnitude of the obtained insulation resistance R2. evaluate.

  In this way, the insulation state evaluation unit 17 outputs information on the current detector 15 that has detected the exploration current Is greater than a predetermined value, and determines the location of insulation deterioration from the arrangement relationship of these current detectors 15. Identify and determine insulation resistance as needed. When insulation degradation occurs at point F2 in FIG. 4, it is determined that insulation degradation has occurred on the upstream side of the current detector 15e3 at a location downstream of the current detector 15e2 on the most downstream side where the exploration current Is2 flows. . Further, the insulation resistance R2 is obtained based on the magnitude of the exploration current Is2 detected by the current detectors 15e2 and 15e1.

  FIG. 5 is an operation explanatory diagram of the insulation monitoring apparatus according to the first embodiment of the present invention when insulation deterioration occurs at two locations on the electric circuit shown in FIG. Now, it is assumed that the insulation resistance R3 is deteriorated at the point F3 in the middle of the feeder 13e, and the insulation resistance R4 is also deteriorated at the point F4 in the middle of the feeder 13b.

  Then, the DC power supply 18 of the DC current supply unit 16, the ground point A, the insulation deterioration point F3, the feeder 13e, the branch distribution bus 12b, the nearest distribution bus 12a, and the closed circuit of the DC power supply 18 of the DC current supply unit 16 (F3 closed circuit). ) And a search current Is3 flows from the DC power supply 18 of the DC current supply unit 16 in the direction indicated by the arrow in FIG. The search current Is3 is detected by the current detectors 15e2 and 15e1 of the feeder 13e.

  Similarly, the DC power supply 18 of the DC current supply unit 16, the ground point A, the insulation deterioration point F4, the feeder 13b, the branch distribution bus 12b, the nearest distribution bus 12a, and the closed circuit of the DC power supply 18 of the DC current supply unit 16 (F4 closed). Circuit) is formed, and the search current Is4 flows from the DC power supply 18 of the DC current supply unit 16 in the direction indicated by the arrow in FIG. This exploration current Is4 is detected by current detectors 15b3, 15b2, and 15b1 of the feeder 13b. A total current Is3 + Is4 of the exploration current Is3 due to the insulation deterioration at the point F3 and the exploration current Is4 due to the insulation deterioration at the insulation deterioration point F4 flows in a part of the ground.

  First, in the F3 closed circuit, when the current detectors 15e2 and 15e1 detect the exploration current Is3, the insulation state evaluation unit 17 determines that the exploration current Is3 detected by the current detectors 15e2 and 15e1 is greater than a predetermined value. It is determined whether or not the value is larger, and when the value is larger than a predetermined value, the information is output to the outside. Thereby, the worker can specify the location of insulation deterioration.

  Moreover, the insulation state evaluation part 17 specifies the location of insulation degradation from the arrangement | positioning relationship of the electric current detectors 15e2 and 15e1. In other words, the insulation state evaluation unit 17 is the current detector 15e2, 15e1 that has detected the exploration current greater than a predetermined value on the load side downstream of the most downstream current detector 15e2 through which the exploration current Is3 flows. Judge that there is a place of insulation deterioration. This is because the exploration current Is3 flowing through the current detector 15e1 upstream of the current detector 15e2 flows due to the influence of insulation deterioration at a location downstream of the current detector 15e2.

  Further, the insulation state evaluation unit 17 evaluates the insulation resistance R3 of the insulation deterioration point F3 based on the magnitude of the exploration current Is3. Using the equations (1) and (2) described above, Is1 in the equation (1) is replaced with Is3 and R1 is replaced with R3 to obtain the insulation resistance R3. The insulation state is determined by the magnitude of the obtained insulation resistance R3. evaluate.

  Similarly, when the current detectors 15b3, 15b2, and 15b1 detect the exploration current Is4 in the F4 closed circuit, the insulation state evaluation unit 17 obtains the exploration current Is4 detected by the current detectors 15b3, 15b2, and 15b1 in advance. It is determined whether or not the value is larger than a predetermined value. If the predetermined value is larger, the information is output to the outside. Thereby, the worker can specify the location of insulation deterioration.

  Moreover, the insulation state evaluation part 17 pinpoints the location of insulation degradation from the arrangement | positioning relationship of electric current detector 15b3, 15b2, 15b1. That is, the insulation state evaluation unit 17 is a load on the downstream side of the most downstream current detector 15b3 through which the search current Is4 flows among the current detectors 15b3, 15b2, and 15b1 that have detected the search current larger than a predetermined value. It is judged that there is a place of insulation deterioration on the side. This is because the exploration current Is4 flowing in the current detectors 15b2 and 15b1 on the upstream side of the current detector 15b3 flows due to the effect of insulation deterioration at a location downstream of the current detector 15b3.

  Furthermore, the insulation state evaluation unit 17 evaluates the insulation resistance R4 at the insulation deterioration point F4 based on the magnitude of the exploration current Is4. Using the above equations (1) and (2), Is1 in the equation (1) is replaced with Is4 and R1 is replaced with R4 to obtain the insulation resistance R4, and the insulation state is determined by the magnitude of the obtained insulation resistance R4. evaluate.

  Thus, even when there is insulation degradation at two locations on the secondary side of the transformer 11, the location of insulation degradation can be identified and the insulation resistance R due to insulation degradation can be evaluated.

  In the first embodiment of the present invention, since the DC current supply unit 16 of the insulation monitoring device is connected to the nearest distribution bus 12 on the secondary side of the transformer 11, insulation deterioration occurs in any of the secondary side electric circuits of the transformer 11. The exploration current Is flows from the downstream side (load side) to the upstream side (transformer side) when viewed from the transformer side. Therefore, it can be determined that among the current detectors 15 that have detected the exploration current Is, there is a portion of insulation deterioration downstream from the most downstream current detector 15 in which the exploration current Is flows when viewed from the transformer side. Thereby, the location of the insulation degradation of the electric circuit with a some branch circuit by a non-grounded distribution system can be specified in a live state.

  Next, a second embodiment of the present invention will be described. FIG. 6 is a simplified system diagram showing an example of an ungrounded power distribution system to which the insulation monitoring device according to the second embodiment of the present invention is applied. This second embodiment is different from the first embodiment shown in FIG. 2 in that the current detector 15T1 and the direct current supply unit 16 are arranged on the transformer side at the connection point between the nearest distribution bus 12a and the branch distribution bus 12b. A current detector 15T2 is additionally provided on the upstream side and a current detector 15T3 is additionally provided on the downstream side when viewed from the transformer 11 across the connection point to the distribution bus 12a. By providing these current detector 15T1, current detector 15T2, and current detector 15T3, it is possible to detect insulation deterioration of the nearest distribution bus 12a and branch distribution bus 12b. The same elements as those in FIG.

  FIG. 7 is an operation explanatory diagram of the insulation monitoring apparatus according to the second embodiment of the present invention when there is insulation deterioration in the middle of the electric circuit shown in FIG. Now, it is assumed that the insulation resistance R5 is deteriorated at the point F5 in the middle of the feeder 13e. Then, the DC power supply 18 of the DC current supply unit 16, the ground point A, the insulation deterioration point F5, the feeder 13e, the branch distribution bus 12b, the nearest distribution bus 12a, and the closed circuit of the DC power supply 18 of the DC current supply unit 16 (F5 closed circuit). ) And a search current Is5 flows from the DC power supply 18 of the DC current supply unit 16 in the direction indicated by the arrow in FIG. This exploration current Is5 is sandwiched between the current detectors 15e2 and 15e1 of the feeder 13e, the current detector 15T1 on the transformer side of the connection point with the branch distribution bus 12b, and the connection point to the nearest distribution bus 12a of the DC current supply unit 16. The current is detected by the downstream current detector 15T3 when viewed from the transformer 11.

  When the current detectors 15e2, 15e1, 15T1, and 15T3 detect the search current Is5 in the F5 closed circuit, the insulation state evaluation unit 17 detects the search current Is5 detected by the current detectors 15e2, 15e1, 15T1, and 15T3. Is larger than a predetermined value, and if it is larger than the predetermined value, the information is output to the outside. Thereby, the worker can specify the location of insulation deterioration.

  Moreover, the insulation state evaluation part 17 specifies the location of insulation degradation from the arrangement | positioning relationship of the current detectors 15e2, 15e1, 15T1, and 15T3. That is, the insulation state evaluation unit 17 is downstream of the most downstream current detector 15e2 through which the exploration current Is1 flows among the current detectors 15e2, 15e1, 15T1, and 15T3 that have detected the exploration current greater than a predetermined value. It is judged that there is a place of insulation deterioration on the load side. In addition, since the current detectors 15e3 and 15e4 on the downstream side of the current detector 15e2 have not detected the exploration current Is5 larger than a predetermined value, the location of insulation deterioration is on the upstream side of the current detector 15e3. to decide.

  Further, the insulation state evaluation unit 17 evaluates the insulation resistance R5 of the insulation deterioration point F5 based on the magnitude of the exploration current Is5. Using the above equations (1) and (2), Is1 in equation (1) is replaced with Is5 and R1 is replaced with R5 to obtain an insulation resistance R5, and the insulation state is determined by the magnitude of the obtained insulation resistance R5. evaluate.

  In this way, the transformer 11 is seen from the transformer 11 across the connection point of the current detector 15T1 and the direct current supply unit 16 to the nearest distribution bus 12a on the transformer side of the connection point between the nearest distribution bus 12a and the branch distribution bus 12b. Even when the current detector 15T2 is additionally provided on the upstream side and the current detector 15T3 is additionally provided on the downstream side, as in the first embodiment of the present invention, the location of insulation degradation can be specified, and the insulation resistance due to insulation degradation can be specified. R can be evaluated. That is, when there is insulation degradation at point F5 in FIG. 7, it is determined that it is upstream of the current detector 15e3 at a location downstream of the most downstream current detector 15e2 through which the exploration current Is5 flows.

  FIG. 8 is an operation explanatory diagram of the insulation monitoring apparatus according to the second embodiment of the present invention when there is insulation deterioration in the branch distribution bus 12b of the electric circuit shown in FIG. Assume that there is an insulation deterioration of the insulation resistance R6 at the point F6 of the branch distribution bus 12b between the drawing point of the feeder 13c and the drawing point of the feeder 13d. Then, the DC power supply 18 of the DC current supply unit 16, the ground point A, the insulation deterioration point F6, the branch distribution bus 12b, and the closed circuit (F6 closed circuit) of the DC power supply 18 of the DC current supply unit 16 are formed. The search current Is6 flows from the DC power supply 18 of the DC current supply unit 16 in the direction indicated by the arrow. This exploration current Is6 is transmitted from the transformer 11 across the connection point of the connection point between the nearest distribution bus 12a and the branch distribution bus 12b on the transformer side of the current detector 15T1 on the transformer side and the nearest distribution bus 12a of the DC current supply unit 16. It is detected by the downstream current detector 15T3. The current detector 15 of each feeder 13 does not detect this exploration current Is6 because a closed circuit passing through each feeder 13 is not formed.

  The insulation state evaluation unit 17 determines whether or not the exploration current Is6 detected by the current detectors 15T1 and 15T3 is larger than a predetermined value when the exploration current Is6 is detected by the current detectors 15T1 and 15T3. When the value is larger than a predetermined value, the information is output to the outside. Thereby, the worker can specify the location of insulation deterioration.

  Moreover, the insulation state evaluation part 17 specifies the location of insulation degradation from the arrangement | positioning relationship of the current detectors 15T1 and 15T3 in F6 closed circuit. That is, the insulation state evaluation unit 17 determines that there is a portion of insulation deterioration in the branch distribution bus 12b on the downstream side of the current detector 15T1. This is because the current detector 15 of each feeder 13 does not detect the search current Is6.

  Further, the insulation state evaluation unit 17 evaluates the insulation resistance R6 of the insulation deterioration point F6 based on the magnitude of the exploration current Is6. Using the equations (1) and (2) described above, Is1 in the equation (1) is replaced with Is6 and R1 is replaced with R6 to obtain the insulation resistance R6, and the insulation state is determined by the magnitude of the obtained insulation resistance R6. evaluate.

  In this way, the insulation state evaluation unit 17 outputs information on the current detector 15 that has detected the exploration current Is greater than a predetermined value, and determines the location of insulation deterioration from the arrangement relationship of these current detectors 15. Identify and determine insulation resistance as needed. When there is insulation degradation at point F6 in FIG. 8, the current detectors of the feeders 13 that have not detected the search current Is6 at a location downstream of the most downstream current detector 15T1 through which the search current Is6 flows. 15, that is, it is determined that there is a portion of insulation deterioration in the branch distribution bus 12 b on the downstream side of the current detector 15 </ b> T <b> 1. Further, the insulation resistance R6 is obtained based on the magnitude of the exploration current Is6 detected by the current detectors 15T1 and 15T3.

  FIG. 9 is an operation explanatory diagram of the insulation monitoring apparatus according to the second embodiment of the present invention, showing an example of the case where insulation deterioration has occurred in two places of the electric circuit shown in FIG. Now, there is an insulation deterioration of the insulation resistance R7 at the point F7 of the branch distribution bus 12b between the drawing point of the feeder 13c and the drawing point of the feeder 13d, and there is an insulation deterioration of the insulation resistance R8 also at the F8 point in the middle of the feeder 13e. Suppose.

  Then, the DC power supply 18 of the DC current supply unit 16, the ground point A, the insulation deterioration point F7, the branch distribution bus 12b, and the closed circuit (F7 closed circuit) of the DC power supply 18 of the DC current supply unit 16 are formed. The exploration current Is7 flows from the DC power supply 18 of the DC current supply unit 16 in the direction indicated by the arrow. The search current Is7 is detected by the current detector 15T1 and the current detector 15T3. Since a closed circuit passing through each feeder 13 is not formed, the current detector 15 of each feeder 13 does not detect this exploration current Is7.

  Similarly, the DC power supply 18 of the DC current supply unit 16, the ground point A, the insulation deterioration point F8, the feeder 13e, the branch distribution bus 12b, the nearest distribution bus 12a, and the closed circuit of the DC power supply 18 of the DC current supply unit 16 (F8 closed). The search current Is8 flows from the DC power supply 18 of the DC current supply unit 16 in the direction indicated by the arrow in FIG. The search current Is8 is detected by the current detectors 15e2, 15e1, the current detector 15T1, and the current detector 15T3 of the feeder 13e. A total current Is7 + Is8 of the exploration current Is7 due to the insulation deterioration at the point F7 and the exploration current Is8 due to the insulation deterioration at the point F8 of insulation flows through a part of the branch distribution bus 12b and the nearest distribution bus 12a.

  Here, when the current detectors 15 of both the current detectors 15e2 and 15e1 of the feeder 13e and the current detectors 15T1 and 15T3 of the distribution bus 12 detect the exploration current Is, as shown in FIG. This is the same not only when there is insulation deterioration in both the power supply line 13 and the distribution bus 12 but also when there is insulation deterioration in the feeder 13 as shown in FIG.

  Therefore, when the search current Is is detected by the current detectors 15e2, 15e1, 15T1, and 15T3, the insulation state evaluation unit 17 determines the search current Is detected by these current detectors 15e2, 15e1, 15T1, and 15T3 in advance. It is determined whether the current value is larger than the predetermined value. If the predetermined value is larger than the predetermined value, the exploration current Is detected by the current detectors 15e2 and 15e1 of the feeder 13 and the current detector 15T1 of the distribution bus 12 The search current Is detected by 15T3 is compared. Then, the information is output to the outside.

  As shown in FIG. 9, when both the feeder 13 and the distribution bus 12 have insulation deterioration, the search current Is detected by the current detectors 15e2 and 15e1 is Is8, and the current detectors 15T1 and 15T3 The detected exploration current Is is Is7 + Is8. The detected exploration current Is is also output externally. Thereby, the worker can easily specify the insulation deterioration point F7 and the insulation deterioration point F8, and can specify the location of the insulation deterioration.

  In the F8 closed circuit, the insulation state evaluation unit 17 specifies the location of insulation deterioration from the arrangement relationship of the current detectors 15e2, 15e1, 15T1, and 15T3 and the magnitude of the search current Is. First, from the arrangement relationship of the current detectors 15e2, 15e1, 15T1, and 15T3, it is determined that there is a location of insulation deterioration on the load side downstream of the most downstream current detector 15e2 through which the exploration current Is flows. On the other hand, from the magnitude of the exploration current Is, it is determined that insulation degradation has occurred between the current detectors 15e1 and 15T1 that have detected different exploration currents Is. Specifically, in the F7 closed circuit, it is determined that insulation deterioration has occurred between the current detector 15T1 that has detected the exploration current Is7 + Is8 and the current detector 15e1 that has detected the exploration current Is8.

  Furthermore, the insulation state evaluation unit 17 evaluates the insulation resistance R7 of the insulation deterioration point F7 based on the magnitude of the exploration current Is7 + Is8 using the above-described equations (1) and (2). Further, the insulation resistance R8 at the insulation deterioration point F8 is evaluated based on the magnitude of the exploration current Is8.

  Thus, even when there is insulation degradation at two locations of the distribution bus 12 and the feeder 13 on the secondary side of the transformer 11, the location of insulation degradation can be identified, and the insulation resistance R due to insulation degradation can be evaluated. Can do.

  FIG. 10 shows the operation of the insulation monitoring apparatus according to the second embodiment of the present invention when there is insulation deterioration downstream of the connection point to the nearest distribution bus 12a of the direct current supply section 16 of the circuit shown in FIG. It is explanatory drawing. Now, it is assumed that the insulation resistance R9 is deteriorated at the point F9 of the nearest distribution bus 12a on the downstream side of the connection point of the direct current supply unit 16 to the nearest distribution bus 12a.

  Then, the DC power supply 18 of the DC current supply unit 16, the ground point A, the insulation deterioration point F9, and the closed circuit (F9 closed circuit) of the DC power supply 18 of the DC current supply unit 16 are formed, and the direction indicated by the arrow in FIG. In addition, a search current Is9 flows from the DC power supply 18 of the DC current supply unit 16. This search current Is9 is detected by the current detector 15T3. Since a closed circuit passing through each feeder 13 is not formed, the current detector 15 of each feeder 13 does not detect this exploration current Is9.

  In the F9 closed circuit, the insulation state evaluation unit 17 determines whether the exploration current Is9 detected by the current detector 15T3 is greater than a predetermined value when the exploration current Is9 is detected by the current detector 15T3. If the value is larger than a predetermined value, the information is output to the outside. Thereby, the worker can specify the location of insulation deterioration.

  Moreover, the insulation state evaluation part 17 specifies the location of insulation degradation from the arrangement | positioning relationship of the current detector 15T3. That is, the insulation state evaluation unit 17 determines that there is a portion of insulation deterioration in the branch distribution bus 12a on the downstream side of the current detector 15T3. This is because the current detector 15T1 and the current detector 15 of each feeder 13 do not detect the search current Is9.

  Further, the insulation state evaluation unit 17 evaluates the insulation resistance R9 at the insulation deterioration point F9 based on the magnitude of the exploration current Is9. Using the equations (1) and (2) described above, Is1 in the equation (1) is replaced with Is9 and R1 is replaced with R9 to obtain the insulation resistance R9, and the insulation state is determined by the magnitude of the obtained insulation resistance R9. evaluate.

  In this way, the insulation state evaluation unit 17 outputs information on the current detector 15 that has detected the exploration current Is greater than a predetermined value, and determines the location of insulation deterioration from the arrangement relationship of these current detectors 15. Identify and determine insulation resistance as needed. When there is insulation degradation at point F9 in FIG. 10, the detector 15T1 that does not detect the exploration current Is9 at each location downstream of the most downstream current detector 15T3 through which the exploration current Is9 flows, and each feeder 13 It is determined that there is a location of insulation deterioration in the nearest distribution bus 12a on the upstream side of the current detector 15, that is, on the downstream side of the current detector 15T3. Further, the insulation resistance R9 is obtained based on the magnitude of the search current Is9 detected by the current detector 15T3.

  FIG. 11 is an operation explanatory diagram of the insulation monitoring apparatus according to the second embodiment of the present invention showing another example in the case where insulation deterioration has occurred in two places of the electric circuit shown in FIG. Now, there is an insulation deterioration of the insulation resistance R10 at the point F10 downstream of the connection point of the DC current supply unit 16 of the electric circuit to the nearest distribution bus 12a, and there is an insulation deterioration of the insulation resistance R11 also at the point F11 in the middle of the feeder 13e. Suppose.

  Then, the DC power supply 18 of the DC current supply unit 16, the ground point A, the insulation deterioration point F10, and the closed circuit (F10 closed circuit) of the DC power supply 18 of the DC current supply unit 16 are formed, and the direction indicated by the arrow in FIG. In addition, the exploration current Is10 flows from the DC power supply 18 of the DC current supply unit 16. This search current Is10 is detected by the current detector 15T3.

  Similarly, the DC power supply 18 of the DC current supply unit 16, the ground point A, the insulation deterioration point F11, the feeder 13e, the branch distribution bus 12b, the nearest distribution bus 12a, and the closed circuit of the DC power supply 18 of the DC current supply unit 16 (F11 closed). Circuit) is formed, and the search current Is11 flows from the DC power supply 18 of the DC current supply unit 16 in the direction indicated by the arrow in FIG. The search current Is11 is detected by the current detectors 15e2, 15e1, the current detector 15T1, and the current detector 15T3 of the feeder 13e. A total current Is10 + Is11 of the exploration current Is10 due to insulation deterioration at the F10 point and the exploration current Is11 due to insulation deterioration at the insulation deterioration point F11 flows through a part of the ground and a part of the nearest distribution bus 12a.

  Here, when the current detectors 15 of both the current detectors 15e2 and 15e1 of the feeder 13 and the current detectors 15T1 and 15T3 of the distribution bus 12 detect the exploration current Is, as shown in FIG. This is the same not only when there is insulation deterioration in both the power supply line 13 and the distribution bus 12 but also when there is insulation deterioration in the feeder 13 as shown in FIG.

  Therefore, when the search current Is is detected by the current detectors 15e2, 15e1, 15T1, and 15T3, the insulation state evaluation unit 17 determines the search current Is detected by these current detectors 15e2, 15e1, 15T1, and 15T3 in advance. It is determined whether the current value is larger than the predetermined value. If the predetermined value is larger than the predetermined value, the exploration current Is detected by the current detectors 15e2 and 15e1 of the feeder 13 and the current detector 15T1 of the distribution bus 12 The search current Is detected by 15T3 is compared. Then, the information is output to the outside.

  As shown in FIG. 11, when there is insulation degradation in both the feeder 13 and the nearest distribution bus 12a downstream of the current detector 15T3, the search current Is detected by the current detectors 15e2, 15e1, and 15T1 is Is11. The search current Is detected by the current detector 15T3 is Is10 + Is11. The detected exploration current Is is also output externally. Thereby, the worker can easily specify the insulation deterioration point F10 and the insulation deterioration point F11, and can specify the location of the insulation deterioration.

  The insulation state evaluation unit 17 specifies the location of insulation deterioration from the arrangement relationship of the current detectors 15e2, 15e1, 15T1, and 15T3 and the magnitude of the search current Is in the F11 closed circuit. First, from the arrangement relationship of the current detectors 15e2, 15e1, 15T1, and 15T3, it is determined that there is a location of insulation deterioration on the load side downstream of the most downstream current detector 15e2 through which the exploration current Is flows. On the other hand, from the magnitude of the exploration current Is, it is determined that insulation deterioration has occurred between the current detectors 15T1 and 15T3 that have detected different exploration currents Is. Specifically, in the F10 closed circuit, it is determined that insulation deterioration has occurred between the current detector 15T3 that has detected the exploration current Is10 + Is11 and the current detector 15T1 that has detected the exploration current Is11.

  Further, the insulation state evaluation unit 17 evaluates the insulation resistance R10 at the insulation deterioration point F10 based on the magnitude of the exploration current Is10 + Is11 using the above-described equations (1) and (2). Further, the insulation resistance R11 at the insulation deterioration point F11 is evaluated based on the magnitude of the exploration current Is10.

  Thus, even when there is insulation degradation at two locations of the distribution bus 12 and the feeder 13 on the secondary side of the transformer 11, the location of insulation degradation can be identified, and the insulation resistance R due to insulation degradation can be evaluated. Can do.

  FIG. 12 shows the operation of the insulation monitoring apparatus according to the second embodiment of the present invention when there is insulation deterioration upstream of the connection point to the nearest distribution bus 12a of the DC current supply unit 16 of the circuit shown in FIG. It is explanatory drawing. Now, it is assumed that the insulation resistance R12 has deteriorated at the F12 point of the nearest distribution bus 12a on the upstream side of the connection point of the DC current supply unit 16 to the nearest distribution bus 12a.

  Then, the DC power supply 18 of the DC current supply unit 16, the ground point A, the insulation deterioration point F12, the nearest power distribution bus 12a, and the closed circuit (F12 closed circuit) of the DC power supply 18 of the DC current supply unit 16 are formed. The search current Is12 flows from the DC power supply 18 of the DC current supply unit 16 in the direction indicated by the arrow. This search current Is12 is detected by the current detector 15T2. Since a closed circuit passing through each feeder 13 is not formed, the current detector 15 of each feeder 13 does not detect this exploration current Is12.

  When the search current Is12 is detected by the current detector 15T2, the insulation state evaluation unit 17 determines whether or not the search current Is12 detected by the current detector 15T2 is larger than a predetermined value. When it is larger than the predetermined value, the information is output to the outside. Thereby, the worker can specify the location of insulation deterioration.

  Moreover, the insulation state evaluation part 17 specifies the location of insulation deterioration from the arrangement | positioning relationship of the current detector 15T2 in F12 closed circuit. That is, the insulation state evaluation unit 17 determines that there is a portion of insulation deterioration in the nearest distribution bus 12a on the upstream side of the current detector 15T2. This is because the current detector 15T2 detects the exploration current Is only when there is a portion of insulation deterioration in the nearest distribution bus 12a on the upstream side of the current detector 15T2.

  Further, the insulation state evaluation unit 17 evaluates the insulation resistance R12 of the insulation deterioration point F12 based on the magnitude of the exploration current Is12. Using the above equations (1) and (2), Is1 in equation (1) is replaced with Is12 and R1 is replaced with R12 to obtain an insulation resistance R12, and the insulation state is determined by the size of the obtained insulation resistance R12. evaluate.

  In this way, the insulation state evaluation unit 17 outputs information on the current detector 15 that has detected the exploration current Is greater than a predetermined value, and determines the location of insulation deterioration from the arrangement relationship of these current detectors 15. Identify and determine insulation resistance as needed. When there is insulation degradation at point F12 in FIG. 12, it is determined that there is a location of insulation degradation in the nearest distribution bus 12a upstream from the current detector 15T2 through which the exploration current Is12 flows. Also, the insulation resistance R12 is obtained based on the magnitude of the search current Is12 detected by the current detector 15T1.

  In the above description, the case where the insulation resistance R12 has deteriorated at the point F12 of the nearest distribution bus 12a upstream of the connection point of the DC current supply unit 16 to the nearest distribution bus 12a has been described. The same can be detected when there is insulation deterioration in the transformer secondary coil upstream of the connection point to the 16 nearest distribution buses 12a. That is, it is possible to detect insulation deterioration at any location upstream of the connection point of the direct current supply unit 16 to the nearest distribution bus 12a. In order to distinguish between the insulation deterioration of the nearest distribution bus 12a and the insulation deterioration of the transformer secondary coil, the current detector 15 may be provided at the boundary between the nearest distribution bus 12a and the transformer secondary coil.

  FIG. 13 is an operation explanatory diagram of the insulation monitoring apparatus according to the second embodiment of the present invention, showing another example when there is insulation degradation at two locations on the electric circuit shown in FIG. Now, there is an insulation deterioration of the insulation resistance R13 at the point F13 upstream of the connection point of the DC current supply unit 16 of the electric circuit to the nearest distribution bus 12a, and there is an insulation deterioration of the insulation resistance R14 also at the point F14 in the middle of the feeder 13e. Suppose.

  Then, the DC power supply 18 of the DC current supply unit 16, the ground point A, the insulation deterioration point F13, and the closed circuit (F13 closed circuit) of the DC power supply 18 of the DC current supply unit 16 are formed, and the directions indicated by the arrows in FIG. In addition, the exploration current Is13 flows from the DC power supply 18 of the DC current supply unit 16. This search current Is13 is detected by the current detector 15T2.

  Similarly, the DC power supply 18 of the DC current supply unit 16, the ground point A, the insulation deterioration point F14, the feeder 13e, the branch distribution bus 12b, the nearest distribution bus 12a, and the closed circuit of the DC power supply 18 of the DC current supply unit 16 (F14 closed). Circuit) is formed, and the search current Is14 flows from the DC power supply 18 of the DC current supply unit 16 in the direction indicated by the arrow in FIG. The search current Is14 is detected by the current detectors 15e2 and 15e1, the current detector 15T1, and the current detector 15T3 of the feeder 13e.

  When the current detectors 15e2, 15e1, 15T1, 15T3, and 15T2 detect the exploration current Is, the insulation state evaluation unit 17 detects the exploration current Is detected by the current detectors 15e2, 15e1, 15T1, 15T3, and 15T2. It is determined whether or not the predetermined value is larger than the predetermined value. If the predetermined value is larger, the information is output to the outside. Thereby, the worker can easily specify the insulation deterioration point F13 and the insulation deterioration point F14, and can specify the location of the insulation deterioration. In addition, as shown in FIG. 13, when both the feeder 13 and the nearest power distribution bus 12a upstream of the current detector 15T2 have insulation deterioration, the search current Is detected by the current detector 15T2 is Is13. The search current Is detected by the current detectors 15e2, 15e1, 15T1, and 15T3 is Is14.

  The insulation state evaluation part 17 specifies the location of insulation degradation from the arrangement | positioning relationship of the current detector 15T2 in F13 closed circuit. That is, the insulation state evaluation unit 17 determines that there is a portion of insulation deterioration in the nearest distribution bus 12a on the upstream side of the current detector 15T2. This is because, as described above, the current detector 15T2 detects the exploration current Is only when there is a location of insulation deterioration in the nearest distribution bus 12a on the upstream side of the current detector 15T2.

  Moreover, the insulation state evaluation part 17 specifies the location of insulation degradation from the arrangement | positioning relationship of the current detectors 15e2, 15e1, 15T1, 15T3, and 15T2 and the magnitude | size of the search electric current Is in F14 closed circuit. First, in the F14 closed circuit, it is determined from the arrangement relationship of the current detectors 15e2, 15e1, 15T1, and 15T3 that there is a location of insulation deterioration on the load side downstream of the most downstream current detector 15e2 through which the exploration current Is flows. .

  Furthermore, the insulation state evaluation unit 17 evaluates the insulation resistance R13 of the insulation deterioration point F13 based on the magnitude of the exploration current Is13 using the above-described equations (1) and (2). Further, the insulation resistance R14 at the insulation deterioration point F14 is evaluated based on the magnitude of the exploration current Is14.

  In this way, even if there is insulation degradation at two locations, the upstream side of the connection point of the direct current supply unit 16 to the nearest distribution bus 12a and the feeder 13, the location of insulation degradation can be identified, and the insulation The insulation resistance R due to deterioration can be evaluated.

  In this case as well, as in the case of FIG. 12, the insulation degradation at any location upstream of the connection point of the direct current supply unit 16 to the nearest distribution bus 12a (the insulation degradation of the nearest distribution bus 12a and the transformer secondary) Side coil insulation deterioration) can be detected. In order to distinguish between the insulation deterioration of the nearest distribution bus 12a and the insulation deterioration of the transformer secondary coil, the current detector 15 may be provided at the boundary between the nearest distribution bus 12a and the transformer secondary coil.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 11 ... Transformer, 12 ... Distribution bus, 13 ... Feeder, 14 ... Switch, 15 ... Current detector, 16 ... DC current supply part, 17 ... Insulation state evaluation part, 18 ... DC power supply, 19 ... Switch

Claims (8)

A circuit in which a plurality of feeders are drawn from a branch distribution bus that branches from the nearest distribution bus on the secondary side of the transformer in a circuit configuration that is not grounded by a non-ground distribution system or a ground distribution system, and the feeder has a plurality of branch circuits A direct current supply unit that is connected to the nearest distribution bus and supplies an exploration current to the electric circuit in a live state when the electric circuit has insulation deterioration ;
A current detector for detecting a probe current supplied from respectively provided on the downstream side of the branching point of the branch circuit the DC current supply unit,
An insulation state evaluation unit for specifying a location of insulation deterioration from an arrangement relationship of current detectors that input a search current detected by the current detector and detected a search current larger than a predetermined value set in advance Insulation monitoring device characterized by.   The insulation state evaluation unit is insulated on a downstream side of a current detector on the most downstream side where the exploration current flows from the transformer side among the current detectors that have detected the exploration current larger than a predetermined value set in advance. The insulation monitoring apparatus according to claim 1, wherein it is determined that there is a portion of deterioration. On the transformer side of the connection point between the nearest distribution bus and the branch distribution bus, the direct current on both sides of the upstream and downstream as viewed from the transformer across the connection point to the nearest distribution bus of the DC current supply unit An additional current detector for detecting the exploration current supplied from the supply unit is provided , and the insulation state evaluation unit is provided downstream of the branch point of these additional current detectors and the branch circuit. 3. The insulation monitoring device according to claim 1 , wherein an insulation deterioration of the nearest distribution bus or the branch distribution bus is detected based on an arrangement relationship of the detected current detectors or a detected exploration current. 4. . The insulation state evaluation unit is a current detector provided on the downstream side of the connection point to the nearest distribution bus of the DC current supply unit, on the transformer side of the connection point of the nearest distribution bus and the branch distribution bus. When the provided current detector and the current detector provided on the downstream side of the branch point of the branch circuit detect an exploration current greater than a predetermined value, the immediate vicinity of the DC current supply unit A current detector provided on the downstream side of the connection point to the distribution bus, and a current flowing through any of the current detectors provided on the transformer side of the connection point between the nearest distribution bus and the branch distribution bus It is determined whether or not it is larger than the current flowing in the current detector provided downstream of the circuit branch point, and when it is larger, it is downstream from the most downstream current detector through which the exploration current flows when viewed from the transformer side. Side and in front of the DC current supply Insulation monitoring device of claim 3, wherein determining that the downstream side of the nearest distribution bus or locations of the insulation deterioration in both the branch distribution bus connection point to the nearest distribution bus there. The insulation state evaluation unit includes a current detector provided downstream of a connection point to the nearest distribution bus of the direct current supply unit, and a transformer side of a connection point between the nearest distribution bus and the branch distribution bus 4. When only the current detector provided in the terminal detects an exploration current larger than a predetermined value, it is determined that there is a portion of insulation deterioration in the branch distribution bus. Insulation monitoring device. When the insulation state evaluation unit detects an exploration current greater than a predetermined value only by a current detector provided on the downstream side of the connection point to the nearest distribution bus of the DC current supply unit, The insulation monitoring apparatus according to claim 3, wherein it is determined that there is a location of insulation deterioration in the nearest distribution bus downstream of the connection point to the nearest distribution bus of the DC current supply unit. When the insulation state evaluation unit detects an exploration current larger than a predetermined value determined only by a current detector provided on the upstream side of the connection point to the nearest distribution bus of the DC current supply unit, The insulation monitoring apparatus according to claim 3, wherein it is determined that there is a location of insulation deterioration in the nearest distribution bus upstream of the connection point to the nearest distribution bus of the DC current supply unit.   The said insulation state evaluation part calculates | requires the insulation resistance of the location of insulation degradation based on the magnitude | size of the search electric current detected by the said current detector, The any one of Claim 1 thru | or 7 characterized by the above-mentioned. The insulation monitoring device described.

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