Power supply capacitor electrostatic capacitance measuring device and power supply capacitor electrostatic capacitance measuring method

Abstract

The object of the present invention is to provide a power supply capacitor electrostatic capacitance measuring device and method capable of suppressing reliability reduction and suppressing electrostatic capacitance measurement errors of a power supply capacitor. The present invention comprises a power supply capacitor (16), a DC power supply (500) for charging the power supply capacitor (16), and a charging switch (501) for switching the connection between the DC power supply (500) and the power supply capacitor (16) to form a charging circuit. A current sensor (504, 505) for detecting the charging current of the power supply capacitor (16) is provided in the charging circuit. The electrostatic capacitance of the power supply capacitor (16) is measured based on a first time (T1) from the start of charging the power supply capacitor (16) to the detection of a first current value (I1) by the current sensor (504), a second time (T2) from the start of charging the power supply capacitor (16) to the detection of a second current value (I2) by the current sensor (505), and a time difference between the first time (T1) and the second time (T2).

Description

Technical Field

[0001] The present invention relates to an apparatus and method for measuring the electrostatic capacitance of a power supply capacitor used in a switching device or the like. Background Art

[0002] The switchgear is provided with a vacuum circuit breaker, which is operated by an electromagnetic operating mechanism. A power supply capacitor is used as the electromagnetic operating mechanism to operate the vacuum circuit breaker. When measuring the electrostatic capacitance of the power supply capacitor, the charge and discharge leads are removed from the power supply capacitor, and the electrostatic capacitance is measured by the electrostatic capacitance, so the equipment needs to be stopped.

[0003] As a technology for solving this problem, there is a technology described in Patent Document 1, for example. In Patent Document 1, a power supply capacitor is discharged for a certain period of time through a discharge circuit connected in parallel with the power supply capacitor, and the voltage of the power supply capacitor at that time is measured, thereby measuring the electrostatic capacitance.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: WO2010 / 150599 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, in the technology described in Patent Document 1, a discharge circuit is separately connected in parallel with the power supply capacitor in order to measure the electrostatic capacitance of the power supply capacitor. This causes a risk of additional failure of the discharge circuit and a problem of reduced reliability.

[0009] Furthermore, if the initial voltage of the power supply capacitor varies when the discharge circuit is connected, the voltage value of the power supply capacitor after the discharge circuit is discharged for a certain period of time also varies, causing an error in the measurement of the electrostatic capacitance of the power supply capacitor.

[0010] An object of the present invention is to provide a power supply capacitor electrostatic capacitance measuring device and a power supply capacitor electrostatic capacitance measuring method which can suppress a decrease in reliability and suppress an error in measuring the electrostatic capacitance of a power supply capacitor.

[0011] Technical solutions to solve problems

[0012] In order to achieve the above-mentioned purpose, the present invention is characterized in that a charging circuit is composed of a power supply capacitor, a power supply for charging the power supply capacitor, and a charging switch for opening and closing the connection between the power supply and the power supply capacitor, and a current sensor for detecting the charging current of the power supply capacitor is provided in the charging circuit, and the electrostatic capacitance of the power supply capacitor is measured based on a first time taken from the start of charging of the power supply capacitor to the detection of the first current value by the current sensor, a second time taken from the start of charging of the power supply capacitor to the detection of the second current value by the current sensor, and the time difference between the first time and the second time.

[0013] Effects of the Invention

[0014] According to the present invention, it is possible to provide a power supply capacitor electrostatic capacitance measuring device and a power supply capacitor electrostatic capacitance measuring method which can suppress a decrease in reliability and suppress an error in measuring the electrostatic capacitance of a power supply capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 1 is a longitudinal sectional view of a switchgear including the vacuum circuit breaker of the first embodiment.

[0016] Figure 2 It is a diagram showing the detailed structure of the vacuum circuit breaker of the first embodiment.

[0017] Figure 3 This is a longitudinal cross-sectional view of the vacuum circuit breaker of Example 1.

[0018] Figure 4 This is a diagram showing a charge and discharge circuit of Example 1.

[0019] Figure 5 This is a block diagram of the storage / comparison unit of the first embodiment.

[0020] Figure 6 1 is a diagram showing the time characteristics of the voltage and current when the power supply capacitor of the first embodiment is charged.

[0021] Figure 7 1 is a diagram showing the time characteristics of the voltage and current when the power supply capacitor of the first embodiment is charged.

[0022] Figure 8 1 is a diagram showing the time characteristics of the voltage and current when the power supply capacitor of the first embodiment is charged.

[0023] Fig. 9 This is a block diagram of the storage / comparison unit of the second embodiment.

[0024] Fig.10 It is a perspective view showing the structure of the current sensor of the third embodiment.

[0025] Fig.11 It is a perspective view showing the structure of a current sensor according to a fourth embodiment.

[0026] Fig.12 It is a perspective view showing the structure of the current sensor of Example 5. DETAILED DESCRIPTION

[0027] Hereinafter, preferred embodiments based on the implementation of the present invention will be described using the accompanying drawings. In addition, the following are merely examples of implementation, and the content of the invention is not limited to the following specific modes. The present invention can of course be modified into various modes including the following modes.

[0028] (Example 1)

[0029] use Figures 1 to 7 Example 1 is described.

[0030] Figure 1 It is a longitudinal sectional view of a switchgear including a vacuum circuit breaker according to Embodiment 1 of the present invention.

[0031] like Figure 1 As shown, the switchgear 150 is divided into a circuit breaker chamber 154 , a measuring chamber 152 arranged above the circuit breaker chamber 154 , a busbar chamber 153 and a cable chamber 155 arranged on the back sides of the circuit breaker chamber 154 and the measuring chamber 152 .

[0032] A vacuum circuit breaker 156 is provided in the circuit breaker chamber 154 .

[0033] The measuring chamber 152 is provided with a control unit 220 for controlling the opening and closing of the main contacts of the vacuum circuit breaker 156; a storage / comparison unit 221 for determining whether there is an abnormality in the state of the vacuum circuit breaker 156 and the type of abnormality; and an abnormal state display unit 222 for displaying that the vacuum circuit breaker 156 is in an abnormal state by lighting (or extinguishing) a lamp, an image, a sound, etc., when the storage / comparison unit 221 determines that the state of the vacuum circuit breaker 156 is abnormal. The storage / comparison unit 221 sequentially stores the measurement results of the electrostatic capacitance of the power supply capacitor, and compares the newly measured results with the previously stored results, thereby detecting abnormalities.

[0034] The busbar chamber 153 is provided with a busbar 162 electrically connected to the fixed contact 7 of the vacuum valve 9 in the vacuum circuit breaker 156 , and a power distribution cable 161 electrically connected to the movable contact 8 of the vacuum valve 9 in the vacuum circuit breaker 156 .

[0035] Moreover, on the front side of the housing of the switch device 150 ( Figure 1A door is provided on the right side of the vacuum circuit breaker 156. When the door is opened, an operation panel including switches and the like provided on the front of the vacuum circuit breaker 156 is exposed. During maintenance and inspection, the operator can open the door and pull out the vacuum circuit breaker 156.

[0036] Next, the detailed structure of the vacuum circuit breaker 156 will be described. Figure 2 It is a diagram showing the detailed structure of the vacuum circuit breaker of the first embodiment.

[0037] like Figure 2 As shown, the vacuum circuit breaker 156 of this embodiment generally includes: a vacuum valve 9 having a main circuit opening and closing part (fixed contact 7 and movable contact 8) inside; an electromagnetic operating device 1 for performing opening and closing operations on the main circuit opening and closing part (fixed contact 7 and movable contact 8) of the vacuum valve 9; and a connecting rod mechanism 2 connecting the electromagnetic operating device 1 and the vacuum valve 9.

[0038] The electromagnetic operating device 1 has a movable iron core 302 and a fixed iron core 306 arranged opposite to each other, and is mainly composed of an electromagnetic operating device side rod 3 and a movable plate 317 connected to the movable iron core 302 that rises and falls in the vertical direction, an electromagnetic coil 17 (load), and an electromagnet 14 in which a permanent magnet 304 is accommodated in a shell 305, and is connected to the first rod 22 via a pin 19, a connecting member 21, and a link mechanism 2. They are arranged in the housing 10.

[0039] In addition, if an excitation current is supplied to the electromagnet coil 17, the movable iron core 302 descends. When the electromagnetic operating device side rod 3 connected to the movable iron core 302 descends, the second rod 23 rotates, the connecting part 24 and the vacuum valve side rod 114 rise, and the fixed contact 7 provided in the vacuum valve 9 contacts the movable contact 8.

[0040] The insulating frame 130 includes a main circuit portion consisting of a circuit breaker 131, 132, a fixed conductor 133, a vacuum valve 9, and a movable side conductor 134. In addition, in order to freely drive the movable contact 8 of the vacuum valve 9 to be separated from the fixed contact 7, it includes a vacuum valve side rod 114, a friction spring 59, a shaft 25, and a circuit breaker spring 60.

[0041] During the closing operation of the vacuum circuit breaker 156, the friction spring 59 and the circuit breaker spring 60 are compressed, and elastic energy is accumulated, and the circuit breaker operation is performed by this elastic energy. When the opening and closing part of the vacuum valve 9 is in the closed state, the movable iron core 302 and the movable plate 317 are held by the attraction force of the permanent magnet 304.

[0042] During the circuit-breaking action of the electromagnetically operated vacuum circuit breaker 156, a current in the opposite direction to the connection action flows through the electromagnet coil 17, thereby generating a magnetic flux in the direction that offsets the attractive force of the permanent magnet 304. The elastic energy stored in the friction spring 59 and the circuit-breaking spring 60 is released, thereby causing the side rod 3 of the electromagnetic operating device to rise, and the fixed contact 7 and the movable contact 8 arranged in the vacuum valve 9 to separate.

[0043] When the electromagnetic operating device side rod 3 rises, the shaft 25 moves upward, and the third rod (not shown) rotates in accordance with the movement of the shaft 25. The third rod and the auxiliary switch 20 are linked, and the auxiliary switch 20 has both the state detection of the opening and closing part of the vacuum valve 9 and the control of the current flowing through the electromagnetic coil 17. During the entry action, the fourth rod (not shown) rotates counterclockwise around the pin and moves to a position where the text "ON" on the display panel (not shown) can be seen from the front side.

[0044] In addition, the auxiliary switch 20 described above is based on the operation timing of the normally open contact and the normally closed contact as the signal contact of the auxiliary switch 20 and the control unit 220 (refer to Figure 1 ) generates a time difference between the time of the on command and the time of the off command (disconnection command), and measures the on action time and the off action time of the vacuum circuit breaker 156. Based on the time change of the measured on action time and the off action time, the state of the vacuum circuit breaker 156, such as the consumption of the fixed contact 7 and the movable contact 8 in the vacuum valve 9, the vacuum leakage of the vacuum valve 9, and the increase in friction of the driving mechanism of the movable contact 8, is determined.

[0045] Figure 3 1 is a longitudinal front cross-sectional view of the vacuum circuit breaker 156 of the first embodiment. A control substrate 18 extending in the vertical direction is fixed to the housing 10. Lead wires 514 extend from the control substrate 18, and the lead wires 514 are connected to the auxiliary switch 20, the power supply capacitor 16, and the electromagnet coil 17. Current sensors 504 and 505 are mounted on the lead wires 514a through which the charging current of the power supply capacitor 16 flows.

[0046] Figure 4 1 is a diagram showing a charging and discharging circuit of Example 1. The charging and discharging circuit is connected to each device through lead wires 514a and 514b. The charging switch 501, the charging resistor 502, and the power supply capacitor 16 are connected to the DC power supply 500 (power supply) through the lead wire 514a to form a charging circuit. And, by turning on the charging switch 501, the power supply capacitor 16 is charged. When the power supply capacitor 16 is charged, the charging switch 501 is turned off.

[0047] In addition, the discharge switch 503 and the electromagnet coil 17 (load) are connected to the power supply capacitor 16 through the lead wire 514b to form a discharge circuit. Then, by turning on the discharge switch 503, current is supplied from the power supply capacitor 16 to the electromagnet coil 17 (load), and the electromagnet 14 is operated. After the electromagnet 14 is operated, the discharge switch 503 is turned off and the charging switch 501 is turned on, thereby recharging the power supply capacitor 16. The charging current at this time is measured by the current sensors 504 and 505.

[0048] Next, use Figure 5 and Figure 6 A method for measuring the electrostatic capacitance of the power supply capacitor 16 will be described. Figure 5 is a block diagram of the storage / comparison unit 221 of the first embodiment. Figure 6 1 is a diagram showing the time characteristics of the voltage and current when the power supply capacitor of the first embodiment is charged.

[0049] exist Figure 5 In this example, multiple digital current sensors are used. Figure 6 As shown, when the initial voltage of the power supply capacitor is 0 V, the power supply capacitor charging current 507 has the following characteristics: it gradually decreases with the time constant CR from the value obtained by dividing the DC power supply voltage by the charging resistance to 0 A. On the other hand, the power supply capacitor voltage 506 has the characteristic of gradually increasing from 0 V to a predetermined DC power supply voltage with the time constant CR as time passes.

[0050] The current sensors 504 and 505 detect the charging current for charging the power supply capacitor 16. As the current sensors 504 and 505, for example, sensors having normally open contacts having different sensitivities to the detected current values ​​are used.

[0051] like Figure 6 As shown, as the power supply capacitor charging current 507 gradually decreases with the time constant CR, when the output signal 601a of the current sensor 504 (first current sensor) intersects the current value I1 (first current value), it switches from closed to open. Similarly, when the output signal 602 of the current sensor 505 (second current sensor) intersects the current value I2, it switches from closed to open. The output signal 601a of the current sensor 504 (first current sensor) and the output signal 602 of the current sensor 505 (second current sensor) switch from closed to open with a time difference dt.

[0052] In Embodiment 1, two current sensors are used in combination. The current sensors 504 and 505 are adjusted so as to digitally switch their outputs when the power supply capacitor charging current 507 crosses the current values ​​I1 and I2, respectively.

[0053] Then, when current sensors 504 and 505 detect different current values, the sensors are switched from closed to open. Then, by measuring the difference between the time when current sensor 504 switches from closed to open and the time when current sensor 505 switches from closed to open, the electrostatic capacitance of the power supply capacitor can be calculated.

[0054] The detection results detected by the current sensors 504 and 505 are respectively stored in the storage units 520 and 521 of the storage / comparison unit 221 .

[0055] In the storage unit 520, in addition to the predetermined current value I1 (first current value), the first time T1 (time that cuts across the current value I1) from the start of charging the power supply capacitor 16 to the time when the current sensor 504 (first current sensor) detects the predetermined current value I1 (first current value) is also stored.

[0056] In the storage unit 521, in addition to the predetermined current value I2 (second current value), the second time T2 (time that cuts across the current value I2) which is the time from when charging of the power supply capacitor 16 starts to when the current sensor 505 (second current sensor) detects the predetermined current value I2 (second current value) is also stored.

[0057] The current value I1 (first current value) and the current value I2 (second current value) are different values. The detection results stored in the storage units 520 and 521 are sent to the difference calculation unit 522 .

[0058] In the difference calculation unit 522, the electrostatic capacitance C of the power supply capacitor 16 is calculated by the following equation based on the time difference dt between the current values ​​I1 and I2 and the times T1 and T2 crossing the current values ​​I1 and I2.

[0059] C=(1 / R)·dt / (ln(I1 / I2))

[0060] Here, if the current values ​​I1 and I2 and the charging resistance R are fixed, the electrostatic capacitance C of the power supply capacitor can be calculated by measuring the time difference dt.

[0061] Next, the power supply capacitor capacitance C calculated by the difference calculation unit 522 is sent to the comparison unit 523, and the calculated power supply capacitor capacitance C is compared with the predetermined time difference judgment value 524 in the comparison unit 523. In the comparison unit 523, it is determined whether the calculated power supply capacitor capacitance C is lower than the time difference judgment value 524. If the calculated power supply capacitor capacitance C is lower than the time difference judgment value 524, a command signal for displaying an abnormality is output to the abnormal state display unit 222. In the abnormal state display unit 222, after receiving the command signal, the abnormality of the power supply capacitor is notified.

[0062] In the above-mentioned embodiment, normally open contact sensors are used as current sensors 504 and 505, but for example, current sensor 504 may be set as a normally closed contact sensor and current sensor 505 may be set as a normally open contact sensor, so that the sensitivity of the current value detected by each sensor is different. Figure 6 As shown, as the power supply capacitor charging current 507 gradually decreases with the time constant CR, when the output signal 601b of the current sensor 504 (first current sensor) becomes 10s, it switches from open to closed. Similarly, when the output signal 602 of the current sensor 505 (second current sensor) becomes 15s, it switches from closed to open. In addition, if the logical AND 603 of the output signal 601b of the current sensor 504 (first current sensor) and the output signal 602 of the current sensor 505 (second current sensor) are monitored, the time difference dt can be measured, and the electrostatic capacitance of the power supply capacitor 16 can be calculated. If the current sensors 504 and 505 are contact outputs, the logical AND 603 can be easily obtained by connecting their respective outputs in series.

[0063] In addition, in this embodiment, the current sensor 504 may be a sensor with a normally open contact, and the current sensor 505 may be a sensor with a normally closed contact. That is, either the current sensor 504 (first current sensor) or the current sensor 505 (second current sensor) may include a normally closed contact, and the other may include a normally open contact.

[0064] In the present embodiment, even when the electrostatic capacitance of the power supply capacitor 16 is different, the electrostatic capacitance of the power supply capacitor 16 can be measured.

[0065] Figure 7 is a graph showing the time characteristics of the voltage and current when the power supply capacitor of Example 1 is charged, including the ratio Figure 6 The electrostatic capacitance of the power supply capacitor used in the power supply capacitor is a small value of electrostatic capacitance. Figure 6 If the current values ​​I1 and I2 are set to Figure 6 are equal, the calculated time difference dt becomes smaller in proportion to the electrostatic capacitance of the power supply capacitor.

[0066] Figure 8 is a graph showing the time characteristics of the voltage and current when the power supply capacitor of Example 1 is charged, showing that the initial voltage of the power supply capacitor 16 includes the ratio Figure 7 In this case, both times T1 and T2 move toward zero, but the time difference dt remains the same. Figure 7 Since the same value is obtained, the electrostatic capacitance can be measured in a state where the variation in the electrostatic capacitance caused by the difference in the initial voltage of the power supply capacitor 16 is suppressed.

[0067] According to this embodiment, since the time difference dt between times T1 and T2 when the power capacitor charging current 507 crosses the current values ​​I1 and I2 is measured, the electrostatic capacitance of the power capacitor 16 can be calculated while suppressing the influence of the initial voltage of the power capacitor.

[0068] Furthermore, according to the present embodiment, when measuring the electrostatic capacitance of the power supply capacitor, it is not necessary to newly provide a discharge circuit, so it is possible to provide a power supply capacitor electrostatic capacitance measuring device that suppresses a decrease in reliability.

[0069] (Example 2)

[0070] Next, use Fig. 9 Embodiment 2 will be described. The same reference numerals are given to the same structures as those in Embodiment 1, and detailed description thereof will be omitted. Fig. 9 This is a block diagram of the storage / comparison unit 221 of the second embodiment. The difference from the first embodiment is that the number of current sensors to be installed is set to a single number (one).

[0071] In the second embodiment, only one current sensor capable of continuously measuring current is provided, and its output is continuously monitored by a microcomputer to calculate the time difference when the power supply capacitor charging current 507 crosses the current values ​​I1 and I2.

[0072] exist Fig. 9 In the example of using a single analog current sensor. Fig. 9 In the example, the detection values ​​continuously detected by the current sensor 901 are sent to the comparison units 902 and 903 and compared with the current determination values ​​904 and 905. The current determination values ​​904 and 905 store the current values ​​I1 and I2 respectively, and the detection values ​​continuously detected by the current sensor 901 are compared with the current values ​​I1 and I2.

[0073] In the comparison unit 902, the time when the analog current value continuously output from the current sensor 901 becomes the current value I1 (first current value) is determined, and the result is stored in the storage unit 520. Similarly, in the comparison unit 903, the time when the analog current value continuously output from the current sensor 901 becomes the current value I2 (second current value) is determined, and the result is stored in the storage unit 521. The subsequent processing is the same as that in the first embodiment, so the detailed description is omitted.

[0074] According to this embodiment, since the time difference dt between the moments T1 and T2 when the power capacitor charging current 507 crosses the current values ​​I1 and I2 is measured, the electrostatic capacitance of the power capacitor 16 can be calculated while suppressing the influence of the initial voltage of the power capacitor. In addition, since the calculation of the electrostatic capacitance of the power capacitor 16 is realized by one current sensor, the cost can be reduced.

[0075] Furthermore, according to the present embodiment, when measuring the electrostatic capacitance of the power supply capacitor, it is not necessary to newly provide a discharge circuit, so it is possible to provide a power supply capacitor electrostatic capacitance measuring device that suppresses a decrease in reliability.

[0076] (Example 3)

[0077] Next, use Fig.10 Example 3 is described. Fig.10 It is a perspective view showing the structure of the current sensor of the third embodiment.

[0078] exist Fig.10 In the embodiment 3, the current sensor is composed of a reed switch 401 and an annular core 402. The annular core 402 is provided with a slit portion 403 in which a part of the outer circumference of the annular core 402 is opened radially outward, and a hollow portion 404 is radially connected to the slit portion 403, and a lead wire 514 is arranged in the hollow portion 404 so as to penetrate the hollow portion 404. The gap in the slit portion 403 is formed to be larger than the diameter of the lead wire 514, and the lead wire 514 is inserted from the slit portion 403 and positioned in the hollow portion 404. The hollow portion 404 is also formed to be larger than the diameter of the lead wire 514.

[0079] The current sensor operates the reed switch 401 by the magnetic flux leaking from the slit portion 403 .

[0080] The outer shell of the reed switch 401 is formed of a glass tube, and two ferromagnetic reeds are arranged inside the glass tube.

[0081] When the reed switch 401 is always in a normally open contact, the two ferromagnetic reeds face each other with a certain contact gap. If a magnetic field is applied to the lead wire of the normally open contact from the outside, the lead wire is magnetized, and the free ends relative to each other attract and contact each other, which can close the circuit. If the magnetic field is eliminated, the circuit can be opened by the elasticity of the lead wire.

[0082] When the reed switch 401 is a normally closed contact, the contacts of the two ferromagnetic reeds are in contact and facing each other. If a magnetic field is applied to the lead wire of the normally closed contact from the outside, the lead wire is magnetized and the relative free ends are separated from each other, which can open the circuit. If the magnetic field is eliminated, the circuit can be closed by the elasticity of the lead wire.

[0083] In order to measure the charging current of the power supply capacitor 16, in the third embodiment, the lead wire 514 is passed through the annular core 402, and the lead wire of the reed switch 401 arranged adjacent to the annular core 402 is magnetized and operated by using the magnetic flux leaking from the slit portion 403 of the annular core 402. Furthermore, when applied to the first embodiment, two current sensors of the third embodiment are included.

[0084] According to the third embodiment, the current can be measured in a non-contact manner.

[0085] In addition, according to Example 3, by providing a gap in the annular core 402 and a portion of the reed switch 401 for allowing the lead 514 to pass through in the lateral direction, and also ensuring a width in the slit portion 403 for allowing the lead 514 to pass through in the lateral direction, the current sensor can be subsequently installed without removing the existing lead 514.

[0086] Furthermore, according to the third embodiment, since the reed switch has a sealed structure, the reliability can be improved.

[0087] Furthermore, according to the third embodiment, the sensitivity can be adjusted by adjusting the width of the slit portion 403 and the gap between the annular magnetic core 402 and the reed switch 401 .

[0088] (Example 4)

[0089] Next, use Fig.11 Embodiment 4 will be described. The same reference numerals are given to the same structures as those in Embodiment 3, and detailed description thereof will be omitted. Fig.11 : is a perspective view showing the structure of the current sensor of Example 4. The difference from Example 3 is that two annular magnetic cores are provided.

[0090] In the fourth embodiment, two annular cores, namely, a first annular core 402a and a second annular core 402b are provided, and a reed switch 401 is arranged between the first annular core 402a and the second annular core 402b.

[0091] The first annular core 402a includes a slit portion 403a in which a portion of the outer circumference of the first annular core 402a is open to the outside in the radial direction, and a hollow portion 404a in communication with the slit portion 403a in the radial direction. The lead wire 514 is disposed in the hollow portion 404a so as to pass through the hollow portion 404a. The gap in the slit portion 403a is formed to be larger than the diameter of the lead wire 514, and the lead wire 514 is inserted from the slit portion 403a and positioned in the hollow portion 404a. The hollow portion 404a is also formed to be larger than the diameter of the lead wire 514.

[0092] Similarly, the second annular core 402b is provided with a slit portion 403b in which a portion of the outer circumference of the second annular core 402b is opened radially outward, and a hollow portion 404b in radial communication with the slit portion 403b, and a lead wire 514 is arranged in the hollow portion 404b so as to penetrate the hollow portion 404b. The gap in the slit portion 403b is formed to be larger than the diameter of the lead wire 514, and the lead wire 514 is inserted from the slit portion 403b and positioned in the hollow portion 404b. The hollow portion 404b is also formed to be larger than the diameter of the lead wire 514.

[0093] According to the fourth embodiment, the first annular magnetic core 402 a and the second annular magnetic core 402 b are arranged so as to sandwich the reed switch 401 , so that the sensitivity of the current sensor can be improved.

[0094] (Example 5)

[0095] Next, use Fig.12 Embodiment 5 will be described. The same reference numerals are given to the same structures as those in Embodiment 3, and detailed description thereof will be omitted. Fig.12 : is a perspective view showing the structure of the current sensor of Example 5. The difference from Example 3 is that two reed switches are provided.

[0096] In Example 5, two reed switches, namely, a first reed switch 401 a and a second reed switch 401 b , are provided, and an annular magnetic core 402 is disposed between the first reed switch 401 a and the second reed switch 401 b .

[0097] When the gap between the first reed switch 401a and the annular core 402 is set to G1 and the gap between the second reed switch 401b and the annular core 402 is set to G2, the current value of the first reed switch 401a and the current value of the second reed switch 401b can be changed by changing the distance between G1 and G2.

[0098] That is, according to the fifth embodiment, by changing the distance between G1 and G2, two output signals having different sensitivities can be obtained.

[0099] Furthermore, according to the fifth embodiment, compared with the case where two current sensors are mounted as in the third embodiment, further miniaturization is possible.

[0100] In addition, the present invention is not limited to the above-described embodiments, and includes various modifications.

[0101] The above-mentioned embodiments are described in detail in order to explain the present invention in an easily understandable manner, and are not limited to necessarily including all the structures described.

[0102] Description of Reference Numerals

[0103] 1… Solenoid operating device, 2… Link mechanism, 3… Solenoid operating device side rod, 7… Fixed contact, 8… Movable contact, 9… Vacuum valve, 10… Housing, 14… Electromagnet, 16… Power supply capacitor, 17… Electromagnet coil, 18… Control board, 19… Pin, 20… Auxiliary switch, 21… Connecting member, 22… First rod, 23… Second rod, 24… Connecting member, 25… Shaft, 59… Friction spring, 60… Break spring, 114… Vacuum valve side rod, 130… Insulation frame, 131... Breaker, 132... Breaker, 133... Fixed conductor, 134... Movable conductor, 150... Switchgear, 152... Measuring instrument room, 153... Busbar room, 154... Breaker room, 155... Cable room, 156... Vacuum circuit breaker, 161... Power distribution cable, 162... Busbar, 220... Control unit, 221... Storage / comparison unit, 222... Abnormal state display unit, 302... Movable iron core, 304... Permanent magnet, 305... Shell, 3 06…Fixed core, 317…Movable plate, 401…Reed switch, 401a…1st reed switch, 401b…2nd reed switch, 402…Annular core, 402a…1st annular core, 402b…2nd annular core, 403…Slit portion, 403b…Slit portion, 404…Hollow portion, 404a…Hollow portion, 404b…Hollow portion, 500…DC power supply, 501…Charging switch, 502…Charging resistor, 503…Discharging switch, 50 4…current sensor, 505…current sensor, 506…power supply capacitor voltage, 507…power supply capacitor charging current, 514…lead, 514a…lead, 514b…lead, 520…storage unit, 521…storage unit, 522…difference calculation unit, 523…comparison unit, 524…time difference judgment value, 603…logical AND, 901…current sensor, 902…comparison unit, 903…comparison unit, 904…current judgment value, 905…current judgment value.

Claims

1. A device for measuring electrostatic capacitance of a power supply capacitor, characterized in that: A charging circuit is formed by a power supply capacitor, a power supply for charging the power supply capacitor, and a charging switch for opening and closing the connection between the power supply and the power supply capacitor. A current sensor for detecting a charging current of the power supply capacitor is provided in the charging circuit. The power supply capacitor electrostatic capacitance measuring device includes a storage / comparison unit that measures the electrostatic capacitance of the power supply capacitor based on a first time taken from the start of charging the power supply capacitor to the detection of a first current value by the current sensor, a second time taken from the start of charging the power supply capacitor to the detection of a second current value different from the first current value by the current sensor, a time difference between the first time and the second time, and a charging resistance of the charging circuit. When the first current value is I1, the second current value is I2, the time difference is dt, the charging resistance is R, and the electrostatic capacitance is C, the electrostatic capacitance is calculated using the formula C=(1 / R)·dt / (ln(I1 / I2)).

2. The power supply capacitor electrostatic capacitance measuring device according to claim 1, characterized in that: The invention comprises a discharge circuit composed of a load and a discharge switch, wherein the load is driven by the power supply capacitor, and the discharge switch switches on and off the connection between the power supply capacitor and the load.

3. The power supply capacitor electrostatic capacitance measuring device according to claim 1 or 2, characterized in that: The current sensor includes a first current sensor for measuring the first current value and a second current sensor for measuring the second current value.

4. The power supply capacitor electrostatic capacitance measuring device according to claim 3, characterized in that: The first current sensor and the second current sensor have different sensitivities in detecting current values.

5. The power supply capacitor electrostatic capacitance measuring device according to claim 4, characterized in that: The outputs of the first current sensor and the second current sensor are digitally switchable, and one of the first current sensor and the second current sensor has a normally closed contact, and the other has a normally open contact.

6. The power supply capacitor electrostatic capacitance measuring device according to claim 1 or 2, characterized in that: The output of the current sensor is a continuously output analog current value.

7. The power supply capacitor electrostatic capacitance measuring device according to claim 1 or 2, characterized in that: The current sensor is composed of a ring-shaped magnetic core and a reed switch. The annular magnetic core includes a slit portion whose outer circumference is partially open to the radial outside and a hollow portion which is connected to the slit portion in the radial direction and through which the lead wire is arranged. The reed switch is operated by the magnetic flux leaking from the slit portion.

8. The power supply capacitor electrostatic capacitance measuring device according to claim 7, characterized in that: The annular magnetic core includes a first annular magnetic core and a second annular magnetic core, The reed switch is arranged between the first annular magnetic core and the second annular magnetic core.

9. The power supply capacitor electrostatic capacitance measuring device according to claim 7, characterized in that: The reed switch includes a first reed switch and a second reed switch, The annular magnetic core is arranged between the first reed switch and the second reed switch.

10. A device for measuring electrostatic capacitance of a power supply capacitor, characterized in that: A charging circuit is formed by a power supply capacitor, a power supply for charging the power supply capacitor, and a charging switch for opening and closing the connection between the power supply and the power supply capacitor. measuring the electrostatic capacitance of the power supply capacitor based on a first time taken from the start of charging the power supply capacitor to the detection of a first current value by a current sensor included in the charging circuit, a second time taken from the start of charging the power supply capacitor to the detection of a second current value different from the first current value by the current sensor, a time difference between the first time and the second time, and a charging resistance of the charging circuit, When the first current value is I1, the second current value is I2, the time difference is dt, the charging resistance is R, and the electrostatic capacitance is C, the electrostatic capacitance is calculated using the formula C=(1 / R)·dt / (ln(I1 / I2)).

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