Inspection device

Abstract

To provide a technique that can check whether a secondary side of a current transformer is in a connected state or an open state before causing a current to flow to a primary side of the current transformer, as a part of inspection of a secondary side circuit of the current transformer.SOLUTION: An inspection device 10 comprises: a checking circuit 20 that is connected in series to a secondary side circuit 3 connected to a secondary side of a current transformer 2, and causes a DC current generated by using a power generator 21 to flow in secondary side wiring 4b to check whether the secondary side of the current transformer 2 is in a connected state or an open state; and a changeover switch 30 that is provided in the secondary side wiring 4b, and connects the checking circuit 20 to the secondary side wiring 4b in inspection of the secondary side circuit 3 and detaches the checking circuit 20 from the secondary side wiring 4b in a normal operation other than the inspection. When the secondary side of the current transformer 2 is determined to be in the connected state in the inspection, the checking circuit 20 notifies a user of a fact that the connected state of the secondary side of the current transformer 2 is normal, and when the secondary side of the current transformer 2 is determined to be in the open state, does not perform the notification.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a device for inspecting the connection state of the secondary side of a current transformer.

Background Art

[0002] Patent Document 1 discloses a secondary side structure of a current transformer that can prevent the current transformer from burning out even when the secondary side of the current transformer is in an open state. In this prior art, a short-circuit circuit is provided that is connected in parallel with the secondary side circuit connected to the secondary side of the current transformer and that enters a short-circuit state when the secondary side voltage of the current transformer becomes a predetermined voltage or higher.

Prior Art Documents

Patent Documents

[0003] [[ID=2C]]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when inspecting the secondary side circuit of a current transformer, the inspection is performed with the current flowing through the primary side of the current transformer stopped. After that, it returns to normal operation. However, if the secondary side of the current transformer is open due to a disconnection or the like in the secondary side circuit of the current transformer and a current is passed through the primary side of the current transformer, the open portion on the secondary side of the current transformer can be in a high voltage state. In this case, in the prior art, the short-circuit circuit operates to enter a short-circuit state, thereby preventing the current transformer from burning out.

[0005] However, conventional technology only addresses the issue after the open section on the secondary side of the current transformer has reached a high voltage state. If the short circuit fails to function for any reason, the open section on the secondary side of the current transformer may remain at a high voltage, potentially causing the current transformer to burn out. To more reliably avoid the secondary side of the current transformer reaching a high voltage state, it is necessary to confirm that the secondary side of the current transformer is not in an open state before returning to normal operation. Generally, the secondary circuit of a current transformer is routed not only to the distribution panel in which the current transformer is installed, but also to multiple distribution panels, control devices, protective devices, monitoring devices, and many other devices. When modifying equipment to which this secondary circuit of a current transformer is routed, it is necessary to confirm that there are no breaks in the secondary circuit.

[0006] The purpose of this disclosure is to provide a technique that allows for easy confirmation of whether the secondary side of a current transformer is connected or open, as part of inspecting the secondary circuit of the current transformer before applying current to the primary side of the current transformer. [Means for solving the problem]

[0007] The first aspect of this disclosure relates to an inspection device. The inspection device includes a confirmation circuit connected in series with a secondary circuit connected to the secondary side of a current transformer, and configured to check whether the secondary side of the current transformer is connected or open by flowing a DC current generated using a generator through the secondary wiring; and a changeover switch provided in the secondary wiring, configured to connect the confirmation circuit to the secondary wiring during inspection of the secondary circuit, and to disconnect the confirmation circuit from the secondary wiring when not inspecting. During inspection, if the confirmation circuit determines that the secondary side of the current transformer is connected, it notifies that the connection state of the secondary side of the current transformer is normal, and does not notify if it determines that the secondary side of the current transformer is open. [Effects of the Invention]

[0008] According to this disclosure, as part of inspecting the secondary circuit of a current transformer, it is possible to easily confirm whether the secondary side of the current transformer is connected or open. [Brief explanation of the drawing]

[0009] [Figure 1] This is a block diagram showing an example configuration of an inspection system according to an embodiment. [Figure 2] This is an explanatory diagram showing a specific example of an inspection device according to an embodiment. [Figure 3] This is an explanatory diagram showing a first example of the locking structure of an inspection device according to an embodiment. [Figure 4] This is an explanatory diagram showing a second example of the locking structure of the inspection device according to the embodiment. [Figure 5] This flowchart shows an example of the processing of the inspection system according to the embodiment. [Modes for carrying out the invention]

[0010] The inspection system and inspection device according to the embodiments of this disclosure will be described with reference to the attached drawings. In addition, elements common to each figure are denoted by the same reference numerals, and redundant explanations are omitted.

[0011] 1. Example Configuration Figure 1 is a block diagram showing an example configuration of inspection system 1 according to an embodiment. Inspection system 1 consists of a current transformer 2, a secondary circuit 3, and an inspection device 10. The current transformer 2 is a device that converts the current flowing from the power source to the primary wiring 4a to 1 / n times (for example, to a size that allows the current to be measured) and flows it to the secondary circuit 3. The current transformer 2 is also called a CT (Current Transformer).

[0012] The current transformer 2 has a primary side structure and a secondary side structure. The primary side structure is a through-type structure that allows, for example, primary side wiring 4a, which carries the current generated by the power supply to the main circuit, to pass through. The secondary side structure has secondary side terminals (secondary side terminals 2a, secondary side terminals 2b) for connecting secondary side wiring 4b, which carries the current generated on the secondary side of the current transformer 2, so that the current is looped through the secondary side circuit 3. The secondary side wiring 4b refers to wiring that connects the two secondary side terminals of the current transformer 2 (secondary side terminals 2a and secondary side terminals 2b) and the secondary side circuit 3 in a ring. The secondary side wiring 4b is composed of wiring 4b1, wiring 4b2, wiring 4b3, wiring 4b4, wiring 4b5, and wiring 4b6, for example, as shown in Figure 1.

[0013] The secondary circuit 3 includes, for example, a protection circuit 5, a monitoring device 6, and a power factor control device 7. The secondary circuit 3 is connected, for example, in the following order: Specifically, the secondary terminal 2a of the current transformer 2 is connected to terminal 30a1 of the first changeover switch 30a by wiring 4b1, terminal 30a2 of the first changeover switch 30a is connected to terminal 30b2 of the second changeover switch 30b by wiring 4b2, terminal 30b1 of the second changeover switch 30b is connected to terminal 5a of the protection circuit 5 by wiring 4b3, terminal 5b of the protection circuit 5 is connected to terminal 6a1 of the ammeter 6a in the monitoring device 6 by wiring 4b4, terminal 6a2 of the ammeter 6a is connected to terminal 7a of the power factor control device 7 by wiring 4b5, and terminal 7b of the power factor control device 7 is connected to the secondary terminal 2b of the current transformer 2 by wiring 4b6.

[0014] The inspection device 10 includes a verification circuit 20 and a changeover switch 30. By operating the changeover switch 30, the verification circuit 20 is connected in series with the secondary circuit 3 or disconnected. The changeover switch 30 includes a first changeover switch 30a and a second changeover switch 30b. The first changeover switch 30a has three terminals, terminals 30a1, 30a2, and 30a3, and is a changeover switch that has a first mode in which terminals 30a1 and 30a2 are connected internally, and a second mode in which terminals 30a1 and 30a3 are connected. In the first mode, terminals 30a1 and 30a3 are not connected, in the second mode, terminals 30a1 and 30a2 are not connected, and in either mode, terminals 30a2 and 30a3 are not connected.

[0015] The second changeover switch 30b has three terminals, terminals 30b1, 30b2, and 30b3, and is a changeover switch that has a first mode in which terminals 30b1 and 30b2 are connected internally, and a second mode in which terminals 30b1 and 30b3 are connected. In the first mode, terminals 30b1 and 30b3 are not connected, in the second mode, terminals 30b1 and 30b2 are not connected, and in either mode, terminals 30b2 and 30b3 are not connected.

[0016] The first changeover switch 30a and the second changeover switch 30b are switched to connect the terminals of the verification circuit 20 to the secondary wiring 4b during inspection of the secondary circuit 3. On the other hand, during normal operation other than inspection of the secondary circuit 3, the first changeover switch 30a and the second changeover switch 30b are switched to disconnect the terminals of the verification circuit 20 from the secondary wiring 4b. In other words, during normal operation, both the first changeover switch 30a and the second changeover switch 30b are in the first mode, and during inspection of the secondary circuit 3, both the first changeover switch 30a and the second changeover switch 30b are in the second mode. During inspection of the secondary circuit 3, the output terminals 20a and 20b of the verification circuit 20 are connected in series to the secondary loop circuit of the current transformer 2.

[0017] The switching operations of the first switching switch 30a and the second switching switch 30b for connecting or disconnecting the terminals of the confirmation circuit 20 and the secondary wiring 4b are manually performed. Also, the switching operations of the first switching switch 30a and the second switching switch 30b may be performed individually, but preferably, the switching operations of the first switching switch 30a and the second switching switch 30b are configured to be interlocked. Thus, by using the switching switch 30 (the first switching switch 30a and the second switching switch 30b), it becomes possible to easily include the confirmation circuit 20 in the loop (including the protection circuit 5, the monitoring device 6, and the power factor control device 7) constituted by the secondary wiring 4b of the secondary circuit 3 of the current transformer 2, and to disconnect the confirmation circuit 20 from that loop.

[0018] The confirmation circuit 20 is a circuit for confirming whether the secondary side of the current transformer 2 is in a connected state or an open state. The confirmation circuit 20 includes a generator 21, a rectifier circuit 22, a capacitor 23, a constant current circuit 24, a bidirectional two-terminal thyristor 25, a notification device 26, an LED 27, and a resistor 27R. The generator 21 is a device that generates an alternating current. An example of the generator 21 is a hand-cranked generator. The rectifier circuit 22 is an element that converts the alternating current generated by the generator 21 into a direct current. The capacitor 23 is a capacitor that smooths the direct current voltage to stabilize it.

[0019] The constant current circuit 24 is a circuit that outputs a constant direct current. Thereby, even if the direct current voltage generated by the generator 21 fluctuates, a constant direct current can flow through the secondary wiring 4b. Incidentally, the constant current circuit 24 is composed of a resistor 24a, a resistor 24b, an NPN transistor 24c, a diode 24d, and a Zener diode 24e. Therefore, when the confirmation circuit 20 is connected to the secondary side of the current transformer 2, even if the output of the generator 21 becomes excessive due to the constant current circuit 24, the current flowing from the confirmation circuit 20 to the secondary side of the current transformer 2 can be kept constant.

[0020] The bidirectional two-terminal thyristor 25 is provided between the output terminals 20a and 20b of the confirmation circuit 20. The bidirectional two-terminal thyristor 25 is an example of an overvoltage protection element that conducts electricity (shorts) between the terminals when a specified voltage is applied. Thereby, even if an abnormal voltage occurs between the output terminals 20a and 20b due to some cause, the secondary side of the current converter 2 can be protected.

[0021] The output of the generator 21 is connected to the AC input of the rectifier circuit 22. The wiring of the positive electrode on the DC side of the rectifier circuit 22 is referred to as the positive electrode wiring, and the wiring of the negative electrode on the DC side of the rectifier circuit 22 is referred to as the negative electrode wiring. The capacitor 23 is connected between the positive electrode wiring and the negative electrode wiring. The resistor 27R and the LED 27 are provided in parallel with the capacitor 23 and are connected between the positive electrode wiring and the negative electrode wiring. Specifically, the positive electrode wiring is connected to the anode of the LED 27 via the resistor 27R. On the other hand, the negative electrode wiring is connected to the cathode of the LED 27. The resistor 27R plays a role of limiting the current flowing through the LED 27.

[0022] The resistor 24a, the diode 24d, and the Zener diode 24e are provided in parallel with the capacitor 23 and are connected between the positive electrode wiring and the negative electrode wiring. Specifically, the positive electrode wiring is connected to the anode of the diode 24d via the resistor 24a, and further, via the diode 24d, it is connected to the cathode of the Zener diode 24e. On the other hand, the negative electrode wiring is connected to the anode of the Zener diode 24e.

[0023] The positive electrode wiring is connected to the output terminal 20b via the notification device 26. The connection point of the resistor 24a and the diode 24d is connected to the base of the NPN transistor 24c. The emitter of the NPN transistor 24c is connected to the negative electrode wiring via the resistor 24b. The collector of the NPN transistor 24c is connected to the output terminal 20a.

[0024] The notification device 26 is a device that notifies that the connection status of the secondary side of the current transformer 2 is normal. For example, when the changeover switch 30 is set to the second mode, that is, when the confirmation circuit 20 and the secondary side wiring 4b are connected, and the confirmation circuit 20 is connected to the loop circuit on the secondary side of the current transformer 2, the notification device 26 notifies that the connection status of the secondary side of the current transformer 2 is normal by utilizing the fact that current flows between output terminals 20b and 20a through the notification device 26. In other words, if the secondary side of the current transformer 2 is open, the notification device 26 does not make the notification because no current flows. This makes it possible to check whether the secondary side of the current transformer 2 is connected or open. Examples of notification devices 26 include a buzzer, a lamp, an LED, etc. The buzzer sounds, or the lamp or LED lights up, indicating that the connection status of the secondary side of the current transformer 2 is normal.

[0025] LED27 is a monitor that monitors the power generation status of the generator 21. When LED27 is lit, it indicates that the generator 21 is generating power, and when LED27 is off, it indicates that the generator 21 is not generating power. Therefore, when inspecting the secondary circuit 3, if the first changeover switch 30a and the second changeover switch 30b are set to the second mode and the generator 21 is operated, and when LED27 lights up, the notification device 26 notifies that the connection status of the secondary side of the current transformer 2 is normal, then it can be determined that the connection status of the secondary side of the current transformer 2 is normal. Also, if LED27 lights up and the notification device 26 does not notify that the connection status of the secondary side of the current transformer 2 is normal, then it can be determined that the secondary side of the current transformer 2 is open.

[0026] As mentioned above, since the secondary circuit 3 of the current transformer 2 is connected to multiple devices, the inductance component of the circuit formed in a loop by the secondary wiring 4b becomes large. However, the output of the verification circuit 20 in this embodiment is DC and is not affected by the inductance component, so it is easy to determine whether or not the secondary circuit 3 of the current transformer 2 is open, even at low voltage.

[0027] 2. Specific Examples 2-1. Examples of inspections using inspection devices Figure 2 is an explanatory diagram showing a specific example of the inspection device 10 according to the embodiment. As shown in case (A) of Figure 2, when current is flowing on the primary side of the current transformer 2, that is, when the electrical equipment is in a powered state, the first changeover switch 30a and the second changeover switch 30b enter the first mode, and the confirmation circuit 20 is not connected to the secondary side wiring 4b. In this case, the inspection device 10 does not use the confirmation circuit 20 to check whether the secondary side of the current transformer 2 is connected or open.

[0028] On the other hand, as shown in cases (B), (C), and (D) of Figure 2, when inspecting the secondary circuit 3 of the current transformer 2 while no current is flowing to the primary side of the current transformer 2, that is, when the upstream main circuit breaker (not shown) connected to the primary wiring 4a is open and the electrical equipment is in a state of power outage, the first changeover switch 30a and the second changeover switch 30b are set to the second mode, and the verification circuit 20 is connected to the secondary wiring 4b. In this case, the inspection device 10 uses the verification circuit 20 to check whether the secondary side of the current transformer 2 is connected or open. Details of each case will be explained below.

[0029] First, in the example shown in Case (B) of Figure 2, the generator 21 is not operating, and this is the state at the start of the inspection of the secondary circuit 3 of the current transformer 2. Since the generator 21 is not operating, there is no notification from the notification device 26 of the inspection device 10, regardless of whether the secondary side of the current transformer 2 is connected or open.

[0030] Next, in the example shown in case (C) of Figure 2, the inspection result of the connection status of the secondary side of the current transformer 2 is shown when the generator 21 is operating and the secondary side of the current transformer 2 is connected during the inspection of the secondary side circuit 3 of the current transformer 2. In this case, the notification device 26 of the inspection device 10 notifies that the secondary side of the current transformer 2 is connected.

[0031] Finally, in the example shown in case (D) of Figure 2, the inspection result of the connection status of the secondary side of the current transformer 2 is shown when the generator 21 is operating and the secondary side of the current transformer 2 is open during the inspection of the secondary circuit 3 of the current transformer 2. In this case, the notification device 26 of the inspection device 10 does not notify that the secondary side of the current transformer 2 is connected. Therefore, when the secondary circuit 3 of the current transformer 2 is inspected, it can be assumed that there is a disconnection in one of the secondary wirings 4b due to being disconnected or the like. Accordingly, an investigation is conducted to find the cause of the disconnection in the secondary wiring 4b, and the disconnection in the secondary wiring 4b is addressed. After restoration, the secondary circuit 3 of the current transformer 2 is inspected again, and the inspection is completed after confirming that the inspection device 10 has notified that it is normal. After the inspection is completed, the first changeover switch 30a and the second changeover switch 30b are switched from the second mode to the first mode.

[0032] 2-2. Examples of safety features in inspection devices 2-2-1. Example 1 Figure 3 is an explanatory diagram showing a first example of the lock structure of the inspection device 10 according to the embodiment. Specifically, Figure 3(A) shows an example of the external shape of the inspection device 10 when the electrical equipment is receiving power, as viewed from above. Figure 3(B) shows an example of the external shape of the inspection device 10 in a side view as in Figure 3(A). Figure 3(C) shows an example of the external shape of the inspection device 10 when the electrical equipment is in the state of inspection start or inspection in progress, as viewed from above. Figure 3(D) shows an example of the external shape of the inspection device 10 in a side view as in Figure 3(C). As shown in Figures 3(A) to 3(D), when the generator 21 is a hand-cranked generator (hereinafter simply referred to as generator 21), a hand-cranked generator handle 21a is provided on the top of the generator 21. Also, near the generator 21, for example, a notification device 26 and a mode switching handle 40 are provided.

[0033] The mode switching handle 40 is equipped with a rotating shaft 41. The locking rod 43 of the electromagnetic lock 42 is configured to switch the rotating shaft 41 between a rotatable state and a non-rotatable state. Therefore, the lock and unlock of the hand crank lock 50 are switched depending on the state of the rotating shaft 41. The excitation and de-excitation of the electromagnetic lock 42 are controlled by an auxiliary contact (not shown) that is linked to a main circuit breaker (not shown) located upstream of the current transformer 2 in the primary wiring 4a.

[0034] For example, when the main circuit breaker is closed, the auxiliary contacts open and the electromagnetic lock 42 is de-energized. As a result, as shown in Figure 3(B), the locking rod 43 protrudes and the rotating shaft 41 becomes immobile. Furthermore, the hand crank lock 50 is locked. When the main circuit breaker is open, the auxiliary contacts close and the electromagnetic lock 42 is energized. As a result, as shown in Figure 3(D), the locking rod 43 is retracted into the electromagnetic lock 42 and the rotating shaft 41 becomes rotatable. Furthermore, the hand crank lock 50 is unlocked.

[0035] By manually turning the mode switching handle 40, the rotating shaft 41 rotates in conjunction, and the changeover switches 30 (first changeover switch 30a, second changeover switch 30b) are switched to connect or disconnect the confirmation circuit 20 and the secondary wiring 4b. When the electrical equipment is receiving power, the confirmation circuit 20 and the secondary wiring 4b are disconnected, and the first changeover switch 30a and the second changeover switch 30b are in the first mode. When the electrical equipment is experiencing a power outage, the electromagnetic lock 42 is energized provided that the main circuit breaker is open, and the locking rod 43 is pulled into the electromagnetic lock 42, allowing the rotating shaft 41 to rotate. In this case, by operating the mode switching handle 40, the confirmation circuit 20 and the secondary wiring 4b are connected, and the first changeover switch 30a and the second changeover switch 30b are in the second mode.

[0036] As shown in Figures 3(A) and 3(B), when the electrical equipment is receiving power, the main circuit breaker is closed, so the electromagnetic lock 42 is de-energized and locked. The hand crank generator handle 21a remains stored in its designated position, and the mode switching handle 40 is fixed by the hand crank handle lock 50 while maintaining the state in which the confirmation circuit 20 and the secondary wiring 4b are disconnected. For example, one end of the hand crank handle lock 50 is fixed to the hand crank generator handle 21a, and the other end is fixed to the mode switching handle 40.

[0037] On the other hand, as shown in Figures 3(C) and 3(D), when the electrical equipment is out of service, the main circuit breaker is open, so the electromagnetic lock 42 is energized and released. Therefore, it becomes possible to operate the mode switching handle 40 and the hand crank handle lock 50. To manually turn the generator 21, the hand crank generator handle 21a, which is stored in a predetermined position, is taken out and the hand crank generator handle 21a is turned manually. The mode switching handle 40 is also operated to connect the confirmation circuit 20 and the secondary wiring 4b. Therefore, in this case, the hand crank generator handle 21a and the hand crank handle lock 50, which are fixedly attached to the mode switching handle 40, are released. In the example shown in Figure 3(D), one end of the hand crank handle lock 50, which is fixedly attached to the hand crank generator handle 21a, is removed to release it.

[0038] Thus, when the inspection device 10 is operated manually, safety features are provided to prevent human error. Specifically, the inspection device 10 is equipped with a locking structure that secures the changeover switch 30 to prevent accidental connection of the confirmation circuit 20 and the secondary wiring 4b, except when inspecting the secondary circuit 3 of the current transformer 2. Therefore, damage to the secondary circuit 3 of the current transformer 2 can be prevented.

[0039] Furthermore, auxiliary contacts that close only in the first mode may be provided in both the first changeover switch 30a and the second changeover switch 30b, and these auxiliary contacts may be connected in series with the closing command circuit of the main circuit breaker closing operation circuit, thereby closing the main circuit breaker only in the first mode.

[0040] 2-2-2. Second Example Figure 4 is an explanatory diagram showing a second example of the lock structure of the inspection device 10 according to the embodiment. Specifically, Figure 4(A) shows an example of the external appearance of the inspection device 10 when the electrical equipment is receiving power, in a top view. Figure 4(B) shows an example of the external appearance of the inspection device 10 when the electrical equipment is unpowered and being inspected, in a top view. As shown in Figures 4(A) and 4(B), the first changeover switch 30a and the second changeover switch 30b are provided with a switch switching lever 60 that can switch both changeover switches in conjunction.

[0041] As shown in Figure 4(A), when the electrical equipment is receiving power, the switch switching lever 60 is pushed in the direction that the first changeover switch 30a and the second changeover switch 30b enter the first mode (i.e., the check circuit 20 and the secondary wiring 4b are disconnected) so that the current output from the secondary terminal 2a of the current transformer 2 flows to the protection circuit 5 without going through the check circuit 20. When the inner door 10e is closed, pushing the switch switching lever 60 puts the first changeover switch 30a and the second changeover switch 30b into the first mode. The inner door 10e is a door that separates live parts from non-live parts so that maintenance personnel and others cannot easily touch the live parts inside the distribution panel when the main door (not shown) is opened. As will be described later, when the electrical equipment is receiving power, the distribution panel is always in the closed position of the inner door 10e.

[0042] On the other hand, as shown in Figure 4(B), if the electrical equipment is out of service and can be inspected, the inner door 10e can be opened. In this case, the switch switching lever 60 is pulled out in the direction that connects the inspection circuit 20 and the secondary wiring 4b so that the current output from the secondary terminal 2a of the current transformer 2 flows to the protection circuit 5 via the inspection circuit 20.

[0043] Furthermore, as shown in Figures 4(A) and 4(B), the inspection device 10 is typically housed in a case 10a and fixedly installed inside the inner door 10e of the switchboard that houses the current transformer 2. Specifically, the case 10a housing the inspection device 10 is fixed to a frame angle 10b provided on the side panel 10d of the switchboard using fixing screws 10c.

[0044] Generally, for safety reasons, distribution panels have an inner door 10e and panel inside the outer main door, so that live parts are not exposed even when the outer main door is opened. Furthermore, when the primary wiring 4a (main circuit) is charged, the inner door 10e of the distribution panel is always closed. In addition, as shown in Figure 4(A), when the electrical equipment is receiving power, current flows to the main circuit, so for safety reasons, the inner door 10e of case 10a is closed. On the other hand, as shown in Figure 4(B), when the electrical equipment is experiencing a power outage, no current flows to the main circuit, so it is not a problem to open the inner door 10e of case 10a. Therefore, the changeover switch 30 can be set to the second mode by pulling out the switch changeover lever 60 only when the inner door 10e is open. Also, because the hand-crank generator handle 21a is located inside case 10a, the hand-crank generator handle 21a can only be operated when the inner door 10e is open.

[0045] Furthermore, as described above, when the inner door 10e is closed, the switch change lever 60 is pushed in, so the first changeover switch 30a and the second changeover switch 30b enter the first mode. Therefore, even if you forget to push in the switch change lever 60 to return from the second mode to the first mode before performing the charging operation, closing the inner door 10e will push in the switch change lever 60, so the first changeover switch 30a and the second changeover switch 30b will switch to the first mode. Note that a cover such as a panel may be used instead of the inner door 10e.

[0046] Thus, when the inspection device 10 is operated manually, safety features are provided to prevent human error. Specifically, the inspection device 10 is equipped with a locking structure that secures the changeover switch 30 to prevent accidental connection of the verification circuit 20 and the secondary wiring 4b, except when inspecting the secondary circuit 3 of the current transformer 2. Therefore, the same effect as in the first example described above can be obtained.

[0047] Furthermore, similar to the first example, in the second example, auxiliary contacts that close only in the first mode may be provided in both the first changeover switch 30a and the second changeover switch 30b, and these auxiliary contacts may be connected in series with the closing command circuit of the main circuit breaker closing operation circuit, thereby closing the main circuit breaker only in the first mode.

[0048] 3. Processing Example Figure 5 is a flowchart showing an example of the processing of the inspection system 1 according to the embodiment.

[0049] In step S100, the inspection system 1 opens the upstream main circuit breaker and performs safety measures such as grounding and voltage detection. This creates a power outage state that allows for the repair and inspection of the electrical equipment. The process then proceeds to step S110.

[0050] In step S110, inspection system 1 performs necessary repairs and inspections of electrical equipment. The process then proceeds to step S120.

[0051] In step S120, the inspection system 1 switches the changeover switch 30 of the inspection device 10 from the first mode to the second mode. The process then proceeds to step S130.

[0052] In step S130, the inspection system 1 operates the generator 21 of the inspection device 10. The process then proceeds to step S140.

[0053] In step S140, the inspection system 1 determines whether the secondary side of the current transformer 2 is connected or not. If it is determined that the secondary side of the current transformer 2 is connected (step S140; Yes), the process proceeds to step S150. Otherwise (step S140; No), the process proceeds to step S190.

[0054] In step S150, the inspection system 1 notifies that the connection status of the secondary side of the current transformer 2 is normal. The process then proceeds to step S160.

[0055] In step S160, the inspection system 1 stops the operation of the generator 21 and switches the changeover switch 30 from the second mode to the first mode. The process then proceeds to step S170.

[0056] In step S170, the inspection system 1 performs a final check before restoration, releases safety measures such as grounding, and closes the door of the distribution panel. The process then proceeds to step S180.

[0057] In step S180, inspection system 1 closes the main circuit breaker and resumes power supply operation of the electrical equipment.

[0058] In step S190, the inspection system 1 does not notify that the connection status of the secondary side of the current transformer 2 is normal. The process then proceeds to step S200.

[0059] In step S200, the inspection system 1 investigates the cause of the disconnection and restores the connection on the secondary side of the current transformer 2, as it has been found to be disconnected.

[0060] Furthermore, according to the above explanation, the changeover switch 30 is composed of two parts: a first changeover switch 30a and a second changeover switch 30b. However, if the confirmation circuit 20 may be at the same potential as the secondary wiring 4b during operation of the electrical equipment, the second changeover switch 30b may be omitted, and the first changeover switch 30a (terminal 30a2) may be configured to connect terminal 5a and output terminal 20b.

[0061] 4. Effects During the inspection of the secondary circuit 3 of the current transformer 2, if the secondary side of the current transformer 2 is connected, a notification is issued indicating that the connection status of the secondary side of the current transformer 2 is normal. If the secondary side of the current transformer 2 is open, no such notification is issued. This makes it easier to inspect the connection status of the secondary circuit of the current transformer 2 of the electrical equipment, and the operation to flow current to the primary side of the current transformer 2 is performed only after confirming that the secondary side of the current transformer 2 is open. Therefore, it is possible to avoid the secondary side of the current transformer becoming high voltage after the inspection of the secondary circuit 3 of the current transformer 2. [Explanation of symbols]

[0062] 1…Inspection system, 2…Current transformer, 2a…Secondary terminal, 2b…Secondary terminal, 3…Secondary circuit, 4a…Primary wiring, 4b…Secondary wiring, 5…Protection circuit, 6…Monitoring device, 6a…Ammeter, 7…Power factor control device, 10…Inspection device, 10a…Case, 10b…Frame angle, 10c…Fixing screw, 10d…Side panel of distribution board, 10e…Inner door, 20…Verification circuit, 21…Generator, 21a…Hand crank for generator, 22…Rectifier circuit, 23…Capacitor, 24…Constant current circuit, 24a,24b…Resistor, 24c…NPN transistor, 24d…Diode, 24e…Zener diode, 25…Bidirectional 2-terminal thyristor, 26…Notification device, 27…LED, 30…Changeover switch, 30a…First changeover switch, 30b…Second changeover switch, 40…Mode switching handle, 50…Manual handle lock, 60…Switch switching lever

Claims

1. A confirmation circuit is connected in series with the secondary circuit connected to the secondary side of the current transformer, and is configured to check whether the secondary side of the current transformer is connected or open by passing a DC current generated using a generator through the secondary wiring. A changeover switch provided in the secondary wiring is configured to connect the verification circuit to the secondary wiring during inspection of the secondary circuit, and to disconnect the verification circuit from the secondary wiring when not inspecting the circuit. Equipped with, The aforementioned verification circuit, in the inspection, If the secondary side of the current transformer is determined to be in the aforementioned connection state, the system will notify that the connection state of the secondary side of the current transformer is normal. The current transformer is configured not to issue the notification if the secondary side is determined to be in the open state. An inspection device characterized by the following features.

2. An inspection device according to claim 1, The aforementioned verification circuit is A constant current circuit that outputs a constant DC current to the secondary wiring, An overvoltage protection element is provided between the terminals, and when the voltage between the terminals becomes an abnormal voltage, it short-circuits the terminals. Equipped with An inspection device characterized by the following features.

3. An inspection device according to claim 1, The aforementioned changeover switch is, A first changeover switch is provided on the secondary wiring and switches between disconnecting and connecting one end of the terminal of the confirmation circuit and the secondary wiring, A second changeover switch is provided on the secondary wiring at a position further away from the current transformer than the first changeover switch, and in conjunction with the first changeover switch, switches between disconnecting and connecting the other end of the terminal of the confirmation circuit and the secondary wiring, including An inspection device characterized by the following features.

4. An inspection device according to any one of claims 1 to 3, The system further includes a locking structure to secure the changeover switch to prevent the confirmation circuit and the secondary wiring from being mistakenly connected in situations other than the aforementioned inspection. An inspection device characterized by the following features.

5. An inspection device according to any one of claims 1 to 3, The aforementioned generator is a hand-cranked generator. An inspection device characterized by the following features.

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