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 an apparatus for checking the connection condition of a secondary side of a current transformer. [Background technology]

[0002] Patent Document 1 discloses a secondary structure of a current transformer that can prevent the current transformer from burning out even if the secondary side of the current transformer is in an open state. This conventional technology includes a short circuit that is connected in parallel with a secondary circuit that is connected to the secondary side of the current transformer and that is short-circuited when the secondary voltage of the current transformer exceeds a predetermined voltage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 08-182183 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when inspecting the secondary circuit of a current transformer, the inspection is performed with the current flowing through the primary side of the current transformer stopped. After that, normal operation is resumed. However, if a current flows through the primary side of the current transformer while the secondary side of the current transformer is open due to a break in the secondary circuit of the current transformer, the open part of the secondary side of the current transformer may be in a high voltage state. In this case, in the conventional technology, the short circuit is activated to create a short circuit, preventing the current transformer from burning out.

[0005] However, the conventional technology is a process after the open part of the secondary side of the current transformer is in a high voltage state. If the short circuit does not function for some reason, the open part of the secondary side of the current transformer will remain at a high voltage, and the current transformer may burn out. In order to more reliably prevent the secondary side of the current transformer from becoming high voltage, it is necessary to check that the secondary side of the current transformer is not in an open state before returning to normal operation. In general, the secondary circuit of a current transformer is not limited to the distribution board where the current transformer is installed, but is often routed through multiple devices such as multiple distribution boards, control devices, protection devices, and monitoring devices. When repairing a device in which the secondary circuit of this current transformer is routed, it is necessary to check that there is no break in the secondary circuit.

[0006] An object of the present disclosure is to provide a technology that can easily check whether the secondary side of a current transformer is in a connected or open state as part of an inspection of the secondary side circuit of the current transformer before current is passed through the primary side of the current transformer. [Means for solving the problem]

[0007] A first aspect of the present 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 pass a direct current generated by a generator through the secondary wiring to confirm whether the secondary side of the current transformer is in a connected state or an open state, and a changeover switch provided in the secondary wiring and 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 during other than inspection. When the secondary side of the current transformer is determined to be in a connected state during inspection, the confirmation circuit notifies the user that the connection state of the secondary side of the current transformer is normal, and does not notify the user when the secondary side of the current transformer is determined to be in an open state. Effect of the Invention

[0008] According to the present disclosure, as part of an inspection of the secondary circuit of a current transformer, it is possible to easily check whether the secondary circuit of the current transformer is in a connected or open state. [Brief description of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a configuration example of an inspection system according to an embodiment. [Diagram 2] FIG. 2 is an explanatory diagram showing a specific example of an inspection device according to an embodiment. [Diagram 3] FIG. 2 is an explanatory diagram showing a first example of a lock structure of an inspection device according to an embodiment. [Figure 4] 6 is an explanatory diagram showing a second example of a lock structure of an inspection device according to an embodiment. FIG. [Diagram 5] 4 is a flowchart showing a processing example of the inspection system according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An inspection system and an inspection device according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. In addition, common elements in the drawings will be denoted by the same reference numerals and duplicated explanations will be omitted.

[0011] 1. Configuration example Fig. 1 is a block diagram showing a configuration example of an inspection system 1 according to an embodiment. The inspection system 1 includes a current transformer 2, a secondary side circuit 3, and an inspection device 10. The current transformer 2 is a device that converts the current flowing from a power source to a primary side wiring 4a into 1 / n times the current (for example, to a value at which the current can be measured) and passes the converted current to the secondary side 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, for example, a through-type structure that allows the primary side wiring 4a that flows the current generated by the power source to pass through the main circuit. The secondary side structure is a structure having secondary side terminals (secondary side terminal 2a, secondary side terminal 2b) for connecting the secondary side wiring 4b that flows the current generated on the secondary side of the current transformer 2 so that the current generated on the secondary side of the current transformer 2 is looped through the secondary side circuit 3. The secondary side wiring 4b means a wiring that connects two secondary side terminals (secondary side terminal 2a and secondary side terminal 2b) of the current transformer 2 and the secondary side circuit 3 in a ring shape. The secondary side wiring 4b is, for example, as shown in FIG. 1, composed of wiring 4b1, wiring 4b2, wiring 4b3, wiring 4b4, wiring 4b5, and wiring 4b6.

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

[0014] The inspection device 10 includes a check circuit 20 and a changeover switch 30. By operating the changeover switch 30, the check circuit 20 is connected in series to or disconnected from the secondary side circuit 3. The changeover switch 30 includes a first changeover switch 30a and a second changeover switch 30b. The first changeover switch 30a has three terminals, ie, a terminal 30a1, a terminal 30a2, and a terminal 30a3, and is a changeover switch having a first mode in which the terminal 30a1 is connected to the terminal 30a2, and a second mode in which the terminal 30a1 is connected to the terminal 30a3. In the first mode, the terminal 30a1 is not connected to the terminal 30a3, and in the second mode, the terminal 30a1 is not connected to the terminal 30a2, and in either mode, the terminal 30a2 is not connected to the terminal 30a3.

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

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

[0017] The switching operation of the first changeover switch 30a and the second changeover switch 30b for connecting or disconnecting the terminal of the confirmation circuit 20 and the secondary wiring 4b is performed manually. The switching operation of the first changeover switch 30a and the second changeover switch 30b may be performed individually, but preferably, the switching operations of the first changeover switch 30a and the second changeover switch 30b are configured to be linked. In this way, by using the changeover switch 30 (the first changeover switch 30a and the second changeover switch 30b), it becomes possible to easily include the confirmation circuit 20 in a loop (including the protection circuit 5, the monitoring device 6, and the power factor control device 7) formed by the secondary wiring 4b of the secondary circuit 3 of the current transformer 2 and to easily separate the confirmation circuit 20 from the loop.

[0018] The confirmation circuit 20 is a circuit that confirms 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 AC current. An example of the generator 21 is a hand-cranked generator. The rectifier circuit 22 is an element that converts the AC current generated by the generator 21 into a DC current. The capacitor 23 is a capacitor that smoothes the DC voltage so as to stabilize it.

[0019] The constant current circuit 24 is a circuit that outputs a constant DC current. This allows a constant DC current to flow through the secondary wiring 4b even if the DC voltage generated by the generator 21 fluctuates. 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 check circuit 20 is connected to the secondary side of the current transformer 2, the constant current circuit 24 allows the current flowing from the check circuit 20 to the secondary side of the current transformer 2 to be kept constant even if the output of the generator 21 becomes excessive.

[0020] The bidirectional two-terminal thyristor 25 is provided between the output terminal 20a and the output terminal 20b of the check circuit 20. The bidirectional two-terminal thyristor 25 is an example of an overvoltage protection element that energizes (short-circuits) between the terminals when a specified voltage is applied. This makes it possible to protect the secondary side of the current transformer 2 even if an abnormal voltage occurs between the output terminal 20a and the output terminal 20b for some reason.

[0021] The output of the generator 21 is connected to the AC input of the rectifier circuit 22. The positive wiring on the DC side of the rectifier circuit 22 is referred to as the positive wiring, and the negative wiring on the DC side of the rectifier circuit 22 is referred to as the negative wiring. The capacitor 23 is connected between the positive wiring and the negative wiring. The resistor 27R and the LED 27 are provided in parallel with the capacitor 23 and connected between the positive wiring and the negative wiring. Specifically, the positive wiring is connected to the anode of the LED 27 via the resistor 27R. On the other hand, the negative wiring is connected to the cathode of the LED 27. The resistor 27R serves to limit 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 and negative wirings. Specifically, the positive wiring is connected to the anode of the diode 24d via the resistor 24a, and is further connected to the cathode of the Zener diode 24e via the diode 24d. On the other hand, the negative wiring is connected to the anode of the Zener diode 24e.

[0023] The positive wiring is connected to the output terminal 20b via the notification device 26. The connection point between 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 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 state 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 state of the secondary side of the current transformer 2 is normal by utilizing the current flowing between the output terminal 20b and the output terminal 20a via the notification device 26. In other words, when the secondary side of the current transformer 2 is in an open state, the notification device 26 does not perform the notification because no current flows. This makes it possible to confirm whether the secondary side of the current transformer 2 is in a connected state or an open state. Examples of the notification device 26 include a buzzer, a lamp, an LED, and the like. By sounding a buzzer or lighting a lamp or an LED, it is notified that the connection state of the secondary side of the current transformer 2 is normal.

[0025] The LED 27 is a monitor that monitors the power generation state of the generator 21. When the LED 27 is lit, it indicates that the generator 21 is generating power, and when the LED 27 is off, it indicates that the generator 21 is not generating power. Therefore, when inspecting the secondary side circuit 3, if the first changeover switch 30a and the second changeover switch 30b are set to the second mode to operate the generator 21, and when the LED 27 is lit, the notification device 26 notifies that the connection state of the secondary side of the current transformer 2 is normal, it can be determined that the connection state of the secondary side of the current transformer 2 is normal. Also, when the LED 27 is lit, if the notification device 26 does not notify that the connection state of the secondary side of the current transformer 2 is normal, it can be determined that the secondary side of the current transformer 2 is in an open state.

[0026] As described above, multiple devices are connected to the secondary circuit 3 of the current transformer 2, so the inductance component of the loop circuit formed by the secondary wiring 4b becomes large. However, the output of the confirmation circuit 20 of this embodiment is direct current 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 disconnected, even at a low voltage.

[0027] 2. Specific examples 2-1. Inspection examples using inspection equipment Fig. 2 is an explanatory diagram showing a specific example of the inspection device 10 according to the embodiment. As shown in case (A) of Fig. 2, when a current flows through the primary side of the current transformer 2, that is, when the state of the electrical equipment is a power receiving state, the first changeover switch 30a and the second changeover switch 30b are in 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 confirm whether the secondary side of the current transformer 2 is in a connected state or an open state.

[0028] On the other hand, as shown in Cases (B), (C), and (D) of Fig. 2, when no current flows through the primary side of the current transformer 2 and the secondary side circuit 3 of the current transformer 2 is inspected, that is, when the upstream main circuit breaker (not shown) connected to the primary side wiring 4a is opened and the state of the electrical equipment is a power outage, the first changeover switch 30a and the second changeover switch 30b are set to the second mode and the confirmation circuit 20 is connected to the secondary side wiring 4b. In this case, the inspection device 10 uses the confirmation circuit 20 to confirm whether the secondary side of the current transformer 2 is in a connected state or an open state. Each case will be described in detail below.

[0029] 2, case (B) is a state in which the generator 21 is not operating and at the start of 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 in a connected or open state.

[0030] 2, case (C) shows an inspection result of the connection state of the secondary side of the current transformer 2 when the generator 21 is in operation and the secondary side of the current transformer 2 is in a connected state during 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 in a connected state.

[0031] Finally, in the example shown in case (D) of FIG. 2, the result of the inspection of the connection state of the secondary side of the current transformer 2 when the generator 21 is operating and the secondary side of the current transformer 2 is in an open state during the inspection of the secondary side circuit 3 of the current transformer 2 is shown. 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 in a connected state. Therefore, when the secondary side circuit 3 of the current transformer 2 is inspected, it can be assumed that any part of the secondary side wiring 4b is in a disconnected state due to non-connection or the like. Therefore, the cause of the disconnected state of the secondary side wiring 4b is investigated, and the disconnected part of the secondary side wiring 4b is treated. After recovery, the secondary side 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 of inspection equipment 2-2-1. First example FIG. 3 is an explanatory diagram showing a first example of a lock structure of the inspection device 10 according to the embodiment. Specifically, FIG. 3(A) shows an example of the outer shape of the inspection device 10 when the state of the electrical equipment is receiving power, as viewed from above. FIG. 3(B) shows an example of the outer shape of the inspection device 10 when viewed from the side in FIG. 3(A). FIG. 3(C) shows an example of the outer shape of the inspection device 10 when the state of the electrical equipment is at the start of inspection or during inspection, as viewed from above. FIG. 3(D) shows an example of the outer shape of the inspection device 10 when viewed from the side in FIG. 3(C). As shown in FIG. 3(A)-FIG. 3(D), when the generator 21 is a hand-cranked generator (hereinafter simply referred to as the generator 21), a hand-cranked generator handle 21a is provided on the upper part of the generator 21. In addition, for example, a notification device 26 and a mode switching handle 40 are provided near the generator 21.

[0033] The mode switching handle 40 has a rotating shaft 41. A 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. Thus, the hand-operated handle lock 50 is switched between locked and unlocked depending on the state of the rotating shaft 41. The excitation and de-excitation of the electromagnetic lock 42 is controlled by an auxiliary contact (not shown) that is linked to a main circuit breaker (not shown) provided upstream of the current transformer 2 in the primary wiring 4a.

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

[0035] By manually turning the mode switching handle 40, the rotating shaft 41 rotates in conjunction with the mode switching handle 40, and the changeover switch 30 (first changeover switch 30a, second changeover switch 30b) is switched so as to connect or disconnect the check circuit 20 and the secondary wiring 4b. When the electrical equipment is receiving power, the check 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 in a power outage, the electromagnetic lock 42 is excited on the condition that the main circuit breaker is in an open state, and the lock rod 43 is drawn into the electromagnetic lock 42, so that the rotating shaft 41 is in a rotatable state. In this case, by operating the mode switching handle 40, the check 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] 3(A) and 3(B), when the electrical equipment is receiving power, the main circuit breaker is in an on state, and the electromagnetic lock 42 is in a non-excited locked state. The hand-cranked power generation handle 21a remains stored in a predetermined position, and the mode switching handle 40 is fixed by the hand-cranked handle lock 50 while maintaining the state in which the check circuit 20 and the secondary wiring 4b are disconnected. For example, the hand-cranked handle lock 50 is fixedly attached at one end to the hand-cranked power generation handle 21a, and at the other end to the mode switching handle 40.

[0037] On the other hand, as shown in Fig. 3(C) and Fig. 3(D), when the electrical equipment is in a power outage, the main circuit breaker is in an open state, and the electromagnetic lock 42 is excited and in an unlocked state. This allows the mode switching handle 40 and the hand-operated handle lock 50 to be operated. The hand-operated power generation handle 21a stored in a predetermined position is taken out to manually rotate the generator 21, and the hand-operated power generation handle 21a is manually rotated. The mode switching handle 40 is also operated to connect the check circuit 20 and the secondary wiring 4b. Therefore, in this case, the hand-operated power generation handle 21a and the hand-operated handle lock 50 fixedly attached to the mode switching handle 40 are released. In the example shown in Fig. 3(D), the hand-operated handle lock 50 is released by removing one end of the hand-operated power generation handle 21a fixedly attached to the hand-operated power generation handle 21a.

[0038] In this way, the inspection device 10 is provided with a safety function as a measure to prevent human erroneous operation when the inspection device 10 is operated manually. Specifically, the inspection device 10 has a lock structure that fixes the change-over switch 30 so that the check circuit 20 and the secondary wiring 4b are not erroneously connected 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, the first changeover switch 30a and the second changeover switch 30b may each be further provided with an auxiliary contact that is closed only in the first mode, and this auxiliary contact may be connected in series to the closing command circuit of the main circuit breaker closing operation circuit, so that the main circuit breaker is closed only in the first mode.

[0040] 2-2-2. Second example Fig. 4 is an explanatory diagram showing a second example of the lock structure of the inspection device 10 according to the embodiment. Specifically, Fig. 4(A) shows an example of the outer shape of the inspection device 10 when the electrical equipment is receiving power, as viewed from above. Fig. 4(B) shows an example of the outer shape of the inspection device 10 when the electrical equipment is in a power outage and is being inspected, as viewed from above. As shown in Figs. 4(A) and 4(B), the first changeover switch 30a and the second changeover switch 30b are provided with a switch changeover lever 60 that can change over both changeover switches in conjunction with each other.

[0041] As shown in FIG. 4(A), when the electrical equipment is receiving power, the switch switching lever 60 is pushed in a direction in which the first changeover switch 30a and the second changeover switch 30b are in the first mode (i.e., the check circuit 20 and the secondary wiring 4b are cut off) so that the current output from the secondary terminal 2a of the current transformer 2 flows to the protection circuit 5 without passing through the check circuit 20. When the inner door 10e is closed, the switch switching lever 60 is pushed in, so that the first changeover switch 30a and the second changeover switch 30b are in the first mode. The inner door 10e is a door for separating the live part from the non-live part so that a maintenance person or the like cannot easily touch the live part in the switchboard when the main door (not shown) is opened. As will be described later, when the electrical equipment is receiving power, the switchboard is always in a state in which the inner door 10e is closed.

[0042] On the other hand, as shown in Fig. 4(B), when the electrical equipment is out of power and can be inspected, the inner door 10e can be opened. In this case, the switch switching lever 60 is pulled out in a direction to connect the check 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 check circuit 20.

[0043] 4(A) and 4(B), the inspection device 10 is typically stored in a case 10a, and is fixedly attached to the inside through an inner door 10e of the switchboard that stores the current transformer 2. Specifically, the case 10a that stores the inspection device 10 is fixed to a frame angle 10b provided on a side panel 10d of the switchboard using fixing screws 10c.

[0044] Generally, for safety reasons, the switchboard is provided with an inner door 10e or panel inside the outer main door, and the charging section is not exposed even if the outer main door is opened. When the primary wiring 4a (main circuit) is charged, the inner door 10e of the switchboard is always closed. Furthermore, as shown in FIG. 4(A), when the electrical equipment is receiving power, the main circuit is in a state where current is flowing, so the inner door 10e of the case 10a is closed for safety reasons. On the other hand, as shown in FIG. 4(B), when the electrical equipment is in a power outage, the main circuit is in a state where no current is flowing, so there is no problem in opening the inner door 10e of the case 10a. Therefore, the switch switch 30 can be set to the second mode by pulling out the switch switch lever 60 only when the inner door 10e is open. Also, since the hand-cranked power generation handle 21a is inside the case 10a, the hand-cranked power generation handle 21a is operated only when the inner door 10e is open.

[0045] Furthermore, as described above, when the inner door 10e is closed, the switch switching lever 60 is pushed in, so that the first changeover switch 30a and the second changeover switch 30b are in the first mode. Therefore, even if the user forgets to push in the switch switching lever 60 to restore the first mode from the second mode before charging, the switch switching lever 60 is pushed in by closing the inner door 10e, so that the first changeover switch 30a and the second changeover switch 30b are shifted to the first mode. Note that a cover such as a panel may be used instead of the inner door 10e.

[0046] In this way, when the inspection device 10 is operated manually, the inspection device 10 is provided with a safety function as a measure to prevent human erroneous operation. Specifically, the inspection device 10 has a lock structure for fixing the change-over switch 30 so as to prevent the check circuit 20 from being erroneously connected to 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] As in the first example, in the second example, the first changeover switch 30a and the second changeover switch 30b may each be further provided with an auxiliary contact that is closed only in the first mode, and this auxiliary contact may be connected in series to the closing command circuit of the main circuit breaker closing operation circuit, so that the main circuit breaker is closed only in the first mode.

[0048] 3. Processing example FIG. 5 is a flowchart showing an example of processing performed by 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 in which the electrical equipment can be repaired and inspected. After that, the process proceeds to step S110.

[0050] In step S110, the inspection system 1 performs necessary repairs and inspections of the electrical equipment. Then, the process 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. After that, the process proceeds to step S130.

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

[0053] In step S140, the inspection system 1 determines whether or not the secondary side of the current transformer 2 is in a connected state. If it is determined that the secondary side of the current transformer 2 is in a connected state (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 state of the secondary side of the current transformer 2 is normal. After that, the process 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. After that, the process proceeds to step S170.

[0056] In step S170, the inspection system 1 performs a final check before restoration, releases safety measures such as grounding, closes the door of the switchboard, etc. After that, the process proceeds to step S180.

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

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

[0059] In step S200, since the connection state on the secondary side of the current transformer 2 is disconnected, the inspection system 1 investigates the cause of the disconnection and performs recovery.

[0060] According to the above description, the changeover switch 30 is composed of two switches, the first changeover switch 30a and the second changeover switch 30b. However, if it does not matter if the check circuit 20 has the same potential as the secondary side wiring 4b during operation of the electrical equipment, the second changeover switch 30b may be omitted and the first changeover switch 30a (terminal 30a2), the terminal 5a, and the output terminal 20b may be connected.

[0061] 4.Effects During inspection of the secondary circuit 3 of the current transformer 2, if the secondary side of the current transformer 2 is in a connected state, a notification is given that the connection state of the secondary side of the current transformer 2 is normal, and if the secondary side of the current transformer 2 is in an open state, no such notification is given. This makes it easy to inspect the connection state of the circuit on the secondary side of the current transformer 2 of the electrical equipment, and an operation to pass a current through the primary side of the current transformer 2 is performed after confirming that the secondary side of the current transformer 2 is in an open state. Therefore, it is possible to prevent the secondary side of the current transformer from becoming a high voltage after 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 switchboard, 10e...Inner door, 20...Check circuit, 21...Generator, 21a...Hand-cranked generator handle, 22...Rectifier circuit, 23...Capacitor, 24...Constant current circuit, 24a,24b...Resistor, 24c...NPN transistor, 24d...Diode, 24e...Zener diode, 25...Bidirectional two-terminal thyristor, 26...Notification device, 27...LED, 30...Change-over switch, 30a...first changeover switch, 30b...second changeover switch, 40...mode changeover handle, 50...handle lock, 60...switch changeover lever

Claims

1. a confirmation circuit connected in series with a secondary circuit connected to a secondary side of a current transformer, the confirmation circuit being configured to pass a direct current generated by a generator through a secondary wiring to confirm whether the secondary side of the current transformer is in a connected state or an open state; A changeover switch provided in the secondary wiring and 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 during other than the inspection; Equipped with The confirmation circuit, in the inspection, If the secondary side of the current transformer is determined to be in the connected state, notify that the connection state of the secondary side of the current transformer is normal; The notification is not performed if the secondary side of the current transformer is determined to be in the open state. An inspection device characterized by:

2. The inspection device according to claim 1, The verification circuit includes: a constant current circuit that outputs a constant DC current to the secondary wiring; an overvoltage protection element provided between the terminals and shorting the terminals when a voltage between the terminals becomes an abnormal voltage; Equipped An inspection device characterized by:

3. The inspection device according to claim 1, The changeover switch is a first changeover switch provided on the secondary wiring and switching between disconnection and connection of one end of the terminal of the confirmation circuit and the secondary wiring; a second changeover switch that is provided on the secondary wiring at a position farther from the current transformer than the first changeover switch and that switches between disconnection and connection of the other end of the terminal of the confirmation circuit and the secondary wiring in conjunction with the first changeover switch; Includes An inspection device characterized by:

4. The inspection device according to any one of claims 1 to 3, The power supply circuit further includes a lock structure for fixing the changeover switch so that the confirmation circuit and the secondary wiring are not erroneously connected during a period other than the inspection. An inspection device characterized by:

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

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