Voltage detector and method for determining short-circuit condition using the same

Abstract

To provide a voltage detector capable of determining a short-circuit condition caused by the remaining presence of a short-circuit grounding device. [Solution] The present invention is a voltage detector for detecting the charge state of an electrical circuit. The voltage detector comprises a voltage detection unit having a conductive detector and electrically connecting the detector to the electrical circuit to be detected in voltage detection mode, thereby detecting the charge state of the electrical circuit, and a short-circuit determination unit having a grounding wire connectable to a grounding terminal provided in the electrical equipment into which the electrical circuit is drawn, and determining the short-circuit state based on the conductivity between the detector electrically connected to the electrical circuit and the grounding terminal in short-circuit determination mode. The short-circuit determination unit determines the short-circuit state between the electrical circuit and the grounding terminal in the electrical equipment based on a response signal transmitted via the detector when a predetermined DC voltage is applied to the grounding terminal.

Description

Technical Field

[0001] The present invention relates to an electroscope, and particularly to an electroscope having a function of determining a short - circuit state of an electric circuit. Further, the present invention relates to a method for determining a short - circuit state using such an electroscope.

Background Art

[0002] For example, in electrical work such as maintenance inspection and replacement and repair work of various electrical equipment, if an operator misidentifies a live - wire state (charged state) electric circuit as a power - off wire state (non - charged state), it may lead to an electric shock accident. Therefore, it is required to confirm the charged state of the electric circuit in advance, and for this purpose, an electroscope is used.

[0003] For example, Patent Document 1 below discloses an electroscope including a detector electrically connected to an electric circuit by contact with the electric circuit, and a main body portion provided with the detector at its tip. By bringing the detector into contact with the electric circuit, the charged state of the electric circuit is determined and notified by the main body portion. This electroscope incorporates a sensor for detecting the contact between the detector and the electric circuit in the main body portion, determines the non - charged state of the electric circuit by a determination circuit based on the detection output of the sensor, and is configured to be able to notify by a lamp and a buzzer.

[0004] Further, Patent Document 2 below discloses a DC electroscope provided with a charging detection unit for detecting a live - wire voltage through a detector fitting by hooking and locking the detector fitting attached to the tip side of a cylindrical operating rod to an overhead line, a disconnection detection unit for detecting a disconnection of a ground wire for grounding the detector fitting through the charging detection unit, and an operation inspection unit for inspecting whether the charging detection unit operates normally, and provided with an electroscope main body in which the charging detection unit, the disconnection detection unit, and the operation inspection unit are housed on the base end side of the operating rod.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] Incidentally, in large factories and facilities, extra-high voltage power from the power company is received by extra-high voltage substations in the higher-level system, stepped down, and then supplied to several lower-level substations. For example, for electrical work at a specific substation, a worker opens the circuit breaker for the circuit leading to that specific substation in the extra-high voltage substation to create a power outage. Then, they install a short-circuit grounding device at the power receiving point of the specific substation to create a short circuit in the circuit connected to the extra-high voltage substation, and then perform various electrical work. After the electrical work at the specific substation is completed, the worker removes the short-circuit grounding device and then closes the circuit breaker to restore power to the circuit.

[0007] However, in reality, ground fault accidents continue to occur due to workers restoring power without removing short-circuit grounding devices. Normally, workers should visually confirm, or be informed by other workers, that no short-circuit grounding devices remain at the site (specific sub-substation equipment) before restoring power, but this is not consistently followed.

[0008] However, while the technology described in the above-mentioned patent document can prevent electric shock accidents by detecting the charge state of the circuit, it did not take into account the determination of a short circuit caused by the remaining short-circuit grounding device as described above.

[0009] Therefore, the present invention aims to provide a voltage detector that can detect the charge state of an electrical circuit and determine a short-circuit state caused by the remaining short-circuit grounding device. [Means for solving the problem]

[0010] The present invention, which solves the above problems, is comprised of the following inventive features or technical characteristics.

[0011] The present invention, in accordance with a certain view, is a voltage detector for detecting the charge state of an electrical circuit. The voltage detector comprises a voltage detection unit having a conductive detector, which detects the charge state of an electrical circuit by electrically connecting the detector to the electrical circuit to be detected in voltage detection mode, and a short-circuit determination unit having a grounding wire connectable to a grounding terminal provided in the electrical equipment into which the electrical circuit is drawn, which determines the short-circuit state based on the conductivity between the detector electrically connected to the electrical circuit and the grounding terminal in short-circuit determination mode. The short-circuit determination unit determines the short-circuit state between the electrical circuit and the grounding terminal in the electrical equipment based on a response signal via the detector when a predetermined DC voltage is applied to the grounding terminal.

[0012] Furthermore, the voltage detector may be equipped with a power supply for applying the predetermined DC voltage to the grounding electrode terminal. The voltage detector may operate in the short-circuit detection mode when the predetermined DC voltage is applied to the grounding electrode terminal from the power supply.

[0013] Furthermore, the voltage detector may further include a notification unit that operates to notify the outside in a manner that indicates voltage detection in a manner that is at least visually and / or audibly recognizable, depending on the charge state of the circuit. The notification unit may also operate to notify in a manner that indicates a short circuit in a manner different from the manner that indicates voltage detection, in a manner that is visually and / or audibly recognizable, when it is determined that a short circuit is occurring.

[0014] Furthermore, the short-circuit detection unit may output a short-circuit detection signal when the response signal exceeds a predetermined operating threshold. The notification unit may then operate to notify in a manner indicating the short-circuit state based on the short-circuit detection signal.

[0015] Furthermore, the voltage detection unit may include an AC voltage detection unit for detecting the AC charging state of the circuit and a DC voltage detection unit for detecting the DC charging state of the circuit.

[0016] Furthermore, the short-circuit detection unit can determine the short-circuit state based on the response signal transmitted via the DC detection unit when the predetermined DC voltage is applied.

[0017] Furthermore, the DC detection unit may include a voltage divider circuit for determining the predetermined operating threshold. The voltage divider circuit may be set such that the predetermined operating threshold is lower than a specified operating threshold required for the DC detection unit to detect the DC charge state of the circuit.

[0018] Furthermore, the short-circuit detection unit may output the short-circuit detection signal when a predetermined DC voltage of 9V is applied from the power supply to the grounding terminal and the voltage of the response signal exceeds at least 5V set by the voltage divider circuit.

[0019] Furthermore, the voltage detector may further include an operating mode control unit that controls whether it operates in the voltage detection mode or the short-circuit detection mode. The operating mode control unit may then control the voltage detection unit to operate in the short-circuit detection mode after it has operated in the voltage detection mode.

[0020] Furthermore, the present invention, from a certain perspective, can also be understood as a short-circuit condition determination device equipped with a voltage detection unit for detecting the charge state of an electrical circuit.

[0021] Another aspect of the present invention is a short-circuit condition determination method for determining a short-circuit condition in electrical equipment into which an electrical circuit is connected, using a voltage detector that detects the charge state of an electrical circuit. The voltage detector comprises a voltage detection unit having a conductive detector and detecting the charge state of an electrical circuit by electrically connecting the detector to the electrical circuit to be detected in voltage detection mode, and a short-circuit determination unit having a grounding wire connectable to a grounding electrode terminal provided in the electrical equipment and determining the short-circuit condition based on the conductivity between the detector electrically connected to the electrical circuit and the grounding electrode terminal in short-circuit determination mode. The short-circuit condition determination method includes, in the short-circuit determination mode, applying a predetermined DC voltage from the voltage detector to the grounding electrode terminal while the detector probe of the voltage detector is electrically connected to the circuit and the grounding wire is electrically connected to the grounding electrode terminal; the short-circuit determination unit receiving a response signal based on the applied predetermined DC voltage; determining a short-circuit condition between the circuit and the grounding electrode terminal in the electrical equipment based on the received response signal; and, if a short-circuit condition is determined to exist, notifying the outside in a manner that is visually and / or audibly recognizable. [Effects of the Invention]

[0022] According to the present invention, a single voltage detector (short-circuit condition detector) can detect the energized state of an electrical circuit and determine if a short-circuit condition exists due to the remaining (forgotten to remove) of a short-circuit grounding device, thereby preventing ground fault accidents. In particular, since the present invention employs a configuration in which the short-circuit condition determination function is incorporated into a conventional voltage detector, workers can perform the short-circuit condition determination work with simple operations similar to those of a familiar voltage detector, and can safely perform the short-circuit condition determination work within a range corresponding to the dielectric strength of the voltage detector. Furthermore, according to the present invention, it is possible to contribute to the creation of sustainable infrastructure through safe electrical work in such electrical equipment.

[0023] Other technical features, objectives, and effects or advantages of the present invention will be illustrated by the following embodiments described with reference to the attached drawings.

Brief Description of the Drawings

[0024] [Figure 1] FIG. 1 is a plan view showing an example of the overall configuration of an electrical detector according to an embodiment of the present invention. [Figure 2] FIG. 2 is a side view showing an example of a state in which the main body of the electrical detection unit of the electrical detector according to an embodiment of the present invention is contracted. [Figure 3] FIG. 3 is a diagram showing an example of a functional model of an electrical detector according to an embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram for explaining the principle of AC electrical detection by an electrical detector according to an embodiment of the present invention. [Figure 5] FIG. 5 is a schematic diagram for explaining the principle of DC electrical detection by an electrical detector according to an embodiment of the present invention. [Figure 6] FIG. 6 is a diagram for explaining the principle of short - circuit state determination by an electrical detector according to an embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing another example of a functional model of an electrical detector according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0025] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments described below are merely examples, and there is no intention to exclude various modifications and applications of technologies not explicitly described below. The present invention can be implemented with various modifications (for example, combining each embodiment) without departing from its gist. Also, in the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. The drawings are schematic and do not necessarily match actual dimensions, ratios, etc. There may be parts where the dimensional relationships and ratios are different between the drawings.

[0026] <The First Embodiment> Figure 1 is a plan view showing an example of the overall configuration of a voltage detector according to one embodiment of the present invention. As shown in the figure, the voltage detector 1 of this embodiment is composed of, for example, a voltage detection unit body 2 and a power box 3. The voltage detector 1 further includes a grounding wire 4 and a connecting wire 5. The voltage detector 1 of this disclosure is a portable electrical device configured to operate in a voltage detection mode capable of detecting (detecting) the charge state of an electrical circuit, and in a short-circuit determination mode capable of determining a short-circuit state of an electrical circuit, as described below. In the figure, the grounding wire 4 is shown connected to the power box 3, but when detecting the DC charge state of an electrical circuit, it may be connected directly to the voltage detection unit body 2 instead of the connecting wire 5, without going through the power box 3. The voltage detector 1 normally operates in voltage detection mode and operates in short-circuit determination mode according to predetermined conditions.

[0027] The main body 2 of the voltage detection unit is a unit composed of, for example, a gripping part 21, an insulating rod 22, a voltage detection part 23, and a detector 24. The gripping part 21 is an insulating part for the worker to grip the main body 2 of the voltage detection unit during work, and is configured in a roughly cylindrical shape with a diameter that is easy for the worker to grip. An insulating rod 22 is provided at one end of the gripping part 21, and the voltage detection part 23 is provided at the end of the rod.

[0028] The insulating rod 22 is a cylindrical member that allows the operator to approach or bring the voltage detection unit 23 close to or into contact with the electrical circuit while maintaining a safe distance from the circuit. The voltage detection unit 23 is connected to the end opposite the gripping unit 21. The insulating rod 22 is typically an extendable and retractable cylindrical member. That is, the insulating rod 22 is composed of multiple insulating tubes connected together, with the diameter decreasing in stages from the largest diameter insulating tube connected to the gripping unit 21 towards the insulating tube on the voltage detection unit 23 side. Therefore, when the operator extends the insulating rod 22, each insulating tube extends passively, and when the operator retracts the insulating rod 22, each insulating tube retracts passively. Figure 2 is a side view showing an example of the voltage detection unit body of a voltage detector according to one embodiment of the present invention in a retracted state. Note that each insulating tube of the insulating rod 22 may have insulating folds formed to effectively insulate surface electricity.

[0029] Returning to Figure 1, the voltage detection unit 23 is configured to include a circuit inside its housing that implements functions related to detecting the charge state of an electrical circuit (voltage detection mode) and determining a short circuit state (short circuit state determination mode). The voltage detection unit 23 is equipped with a detector 24 at its tip. The detector 24 is a conductive terminal for electrically connecting the voltage detection unit 23 to the electrical circuit CR to be detected. In addition, a notification unit 25 is provided on the surface of the housing of the voltage detection unit 23 to notify the outside (i.e., the worker) of the detection and determination. The notification unit 25 includes, for example, light-emitting units 25a and 25b that emit light in a manner that can be visually recognized by the worker, and a sound-emitting unit 25c that sounds in a manner that can be audibly recognized by the worker. In addition, a push-button type switch 26 is provided on the surface of the housing of the voltage detection unit 23 for performing a self-test to determine whether the voltage detection unit 23 is functioning correctly. The worker presses the switch 26 before actually checking the charge state of the electrical circuit to confirm whether the voltage detection unit 23 is functioning correctly.

[0030] In this disclosure, the voltage detection unit 23 is configured to function as a dual AC / DC voltage detector in voltage detection mode. Specifically, the voltage detection unit 23 includes an AC voltage detection unit for detecting the AC charging state of the circuit (AC voltage detection) and a DC voltage detection unit for detecting the DC charging state of the circuit (DC voltage detection) (see Figure 3). Furthermore, as will be described later, the voltage detector 1 is configured to be able to determine the short-circuit state of the circuit using the function of the DC voltage detection unit in the short-circuit state determination mode.

[0031] The power box 3 is a unit that houses a power supply 31 inside its casing for supplying a predetermined DC voltage to determine if a circuit is short-circuited. The power supply 31 is, for example, a battery with a DC voltage of 9V, but is not limited to this. The power box 3 has sockets 32 for connecting the grounding wire 4 and the connecting wire 5, respectively. The power box 3 is used when the circuit is short-circuited. That is, when the circuit is short-circuited, the power box 3 is electrically connected to the grounding terminal via the grounding wire 4, while being electrically connected to the voltage detection unit body 2 via the connecting wire 5. The power box 3 also has a power switch 33 on the surface of its casing. When the power switch 33 is activated, the voltage detector 1 operates in short-circuit detection mode, and a predetermined DC voltage is supplied to the grounding terminal via the connecting wire 4.

[0032] In this example, the power box 3 is configured as a unit separate from the voltage detection unit body 2, but this is not limited to this configuration. For example, it may be housed inside the gripping unit 21 and configured integrally with the voltage detection unit body 2.

[0033] The grounding wire 4 is a conductive member for electrically connecting the voltage detector 1 to the grounding terminal provided on the electrical equipment. For example, one end is provided with a grounding clip 41 and the other end with a pin plug 42. When the voltage detector 1 is used to detect DC voltage in an electrical circuit, typically the grounding clip 41 of the grounding wire 4 is connected to the grounding terminal of the electrical equipment, while the pin plug 42 is connected to the socket 27 of the voltage detector body 2. Therefore, the use of the power box 3 and connecting wire 5 is not essential when detecting DC voltage. Also, when the voltage detector 1 is used to determine if an electrical circuit is short-circuited, the grounding clip 41 of the grounding wire 4 is connected to the grounding terminal of the electrical equipment, while the pin plug 42 is connected to the socket 32 ​​of the power box 3.

[0034] As described above, the connecting wire 5 is a conductive member for electrically connecting the voltage detection unit body 2 and the power supply 3, and for example, pin plugs 51 and 52 are provided at both ends. When determining whether an electrical circuit is short-circuited, the pin plugs 51 and 52 of the connecting wire 5 are connected to the socket 27 of the voltage detection unit body 2 and the socket 32 ​​of the power supply 3, respectively.

[0035] In this example, the grounding wire 4 and connecting wire 5 are configured to be plugged in and unplugged depending on the work being done, but this is not limited to this configuration. For example, a switchable power switch 33 provided in the power box 3 may be used to switch between a circuit connection configuration to the voltage detection unit body 2 via the power supply 31 and a circuit connection configuration to the voltage detection unit body 2 without using the power supply 31.

[0036] Figure 3 shows an example of a functional model of a voltage detector according to one embodiment of the present invention. As shown in the figure, the voltage detector 1, as a functional model corresponding to the voltage detection unit 2, includes, for example, a main power supply 231, a limiting resistor 232, a measuring resistor 233, a capacitor 234, an AC operating threshold adjustment unit 235, a DC operating threshold adjustment unit 236, an AC level detection unit 237, a DC level detection unit 238, a notification control unit 239, a notification unit 25, and a switch 26. The voltage detector 1 is also shown as an example in which a power supply 31 and a power switch 33 are included as a functional model corresponding to the power supply box 3. In the figure, the same reference numerals are used for functional elements corresponding to the components of the voltage detector 1 shown in Figure 1.

[0037] The main power supply 231 supplies the voltage necessary for the operation of the voltage detector 1. Specifically, the voltage from the main power supply 231 is converted to a predetermined reference voltage and input to the AC level detection unit 237 and the DC level detection unit 238, respectively. Although not shown in the figures, the main power supply 231 also supplies the driving power for the notification unit 25.

[0038] The limiting resistor 232 is an insulating resistor that protects the internal circuit from the current flowing through the circuit CR. The limiting resistor 232 has a resistance value of, for example, 10 to 100 MΩ or more, which is selected according to the voltage of the circuit being tested by the voltage detector 1.

[0039] The measuring resistor 233 is a resistor used to detect the charge state of the circuit CR. The measuring resistor 233 determines the potential difference between an operating threshold based on a predetermined reference voltage and the voltage from the circuit CR. For example, in the case of AC detection, the resistance value of the measuring resistor 233 is selected so that it is possible to detect the voltage of the current flowing to the ground from the detector 24 electrically connected to the circuit CR via the stray capacitance to ground of the detector 1. In the case of DC detection, it is selected so that it is possible to detect the voltage of the current flowing to the grounding terminal E from the detector 24 electrically connected to the circuit CR.

[0040] Capacitor 234 is a capacitor that cuts off DC current from flowing into the AC level detection unit 237 via the detector 24 electrically connected to the circuit CR. This protects the AC level detection unit 237 from DC current flowing in from the circuit CR during DC voltage detection. Note that when AC voltage is detected, if AC current enters from the detector 24 electrically connected to the circuit CR, a virtual closed circuit is not formed, and therefore the DC level detector 238 does not operate. Consequently, when DC voltage detection, the operator needs to connect the grounding wire 4 to the grounding terminal E (i.e., earth) of the voltage detector 1 to form a closed circuit with the circuit CR, but when AC voltage detection, it is not necessary to connect the grounding wire 4 to the grounding terminal E (i.e., earth) of the voltage detector 1.

[0041] The AC operating threshold adjustment unit 235 defines a first operating threshold for the AC level detection unit 237 during AC voltage detection. For example, the AC operating threshold adjustment unit 235 is composed of a voltage divider circuit that divides the voltage of the main power supply 231. Therefore, the first operating threshold can be set by appropriately setting the ratio of resistance values ​​in the voltage divider circuit.

[0042] The DC operating threshold adjustment unit 236 defines a second operating threshold for the DC level detector 238 during DC voltage detection. Similarly, the DC operating threshold adjustment unit 236 is composed of, for example, a voltage divider circuit that divides the voltage of the main power supply 231. Therefore, the second operating threshold can be set by appropriately setting the ratio of resistance values ​​in the voltage divider circuit.

[0043] The AC level detection unit 237 compares the voltage of the alternating current flowing in from the circuit CR with a first operating threshold defined by the AC operating threshold adjustment unit 235 to determine whether the voltage of the alternating current exceeds the first operating threshold. If it determines that the voltage of the alternating current exceeds the first operating threshold, it outputs a first detection signal to the notification control unit 239. In this disclosure, the AC operating threshold adjustment unit 235 and the AC level detection unit 237 function as AC voltage detection units.

[0044] The DC level detection unit 238 compares the voltage of the DC current (response signal) flowing in from the circuit CR with a second operating threshold defined by the DC operating threshold adjustment unit 236 to determine whether the voltage of the DC current exceeds the second operating threshold. If it determines that the voltage of the DC current exceeds the second operating threshold, it outputs a second detection signal (or short-circuit detection signal) to the notification control unit 239. In this disclosure, the DC operating threshold adjustment unit 236 and the DC level detection unit 238 function as both a DC voltage detection unit and a short-circuit condition determination unit.

[0045] Furthermore, the DC operating threshold adjustment unit 236 and the DC level detection unit 238 function as a short-circuit state determination unit that determines the short-circuit state of the CR circuit in short-circuit determination mode.

[0046] The notification control unit 239 controls the notification unit 25 to drive in a manner that indicates at least visually and / or audibly recognizable voltage detection corresponding to the charge state of the circuit CR, based on either the first detection signal output from the AC level detection unit 237 or the second detection signal output from the DC level detection unit 238.

[0047] The notification unit 25 includes light-emitting units 25a and 25b that emit light in a manner that can be visually recognized by the worker, and a sound-emitting unit 25c that makes a sound in a manner that can be audibly recognized by the worker. The light-emitting unit 25a is, for example, a first LED that emits visible light of a first wavelength (e.g., red), and the light-emitting unit 25b is a second LED 25b that emits visible light of a second wavelength (e.g., orange). The sound-emitting unit 25c is, for example, a speaker that emits an electronic sound.

[0048] For example, based on a first detection signal output from the AC level detection unit 237, the notification control unit 239 outputs a drive signal to the light-emitting unit 25a (red LED) so that the light-emitting unit 25a flashes, and also activates the sound-emitting unit 25c so that a predetermined notification sound is emitted, in a manner indicating the detection of AC charging. Also, based on a second detection signal output from the DC level detection unit 238, the notification control unit 239 outputs a drive signal to the light-emitting unit 25b (orange LED) so that the light-emitting unit 25b flashes, and also activates the sound-emitting unit 25c so that a predetermined notification sound is emitted, in a manner indicating the detection of DC charging. The predetermined notification sound may be the same for AC charging detection and DC charging detection, or it may be different.

[0049] Furthermore, the notification control unit 239 controls the notification unit 25 to drive in a manner that indicates a short-circuit state that is visually and / or audibly recognizable, based on a short-circuit detection signal described later. For example, as a manner that indicates a short-circuit state, the notification control unit 239 outputs a drive signal to the light-emitting units 25a and 25b so that they flash alternately, and also activates the sound-emitting unit 25c so that a predetermined notification sound is emitted. The manner of illumination is not limited to alternating flashing, but can be any manner that is recognizable to the user. The predetermined notification sound may be the same as, or different from, the notification sound for detecting AC charging or DC charging states described above.

[0050] Switch 26 is a push-button type switch for performing a self-test to determine whether the voltage detection unit 23 is functioning correctly. When switch 26 is pressed, it becomes conductive, and the notification unit 25 is driven based on the voltage applied from the main power supply 231. This allows the operator to confirm that the voltage of the main power supply 231 of the voltage detector 1 is interrupted and that the notification unit 25 is functioning correctly.

[0051] Next, the functional model of the power box 3 will be described. In the figure, the power box 3 is shown to be electrically connected to the grounding terminal E via the grounding wire 4 and electrically connected to the main body 2 via the connecting wire 5.

[0052] The power supply 31 is a constant voltage source that supplies a predetermined DC voltage to the voltage detector 1 to enable it to determine if a short circuit is present in the circuit. The power supply 31 is, for example, a battery with a DC voltage of 9V, but is not limited to this. In this example, the positive terminal of the power supply 31 is located on the ground terminal E side.

[0053] The power switch 33 is a switch for applying a predetermined DC voltage to form a virtual closed circuit (conducting state) from the grounding terminal through the circuit CR to the voltage detector 1. In this example, when the power switch 33 is operated to the conducting state (ON), a predetermined DC voltage is applied from the power supply 31 to the grounding terminal E. This makes it possible to observe the response signal to the predetermined DC voltage applied to the grounding terminal E in the closed circuit from the grounding terminal E through the circuit CR to the voltage detector 1. In other words, when the voltage detector 1 is used in conventional DC voltage detection work, the voltage detector 1 will detect the power outage state (no charge state) of the circuit CR. Therefore, if a DC current is flowing through the circuit CR, the DC level detection unit 238 can detect the voltage of that DC current and output a second detection signal, which can drive and control the notification unit 25. On the other hand, in the process of determining a short circuit, the circuit CR should be in a de-energized state (at least the workers think so). Therefore, the voltage detector 1 is supplied with a predetermined DC voltage from the power supply 31, enabling the DC level detection unit 238 to detect the DC voltage (response signal).

[0054] Figure 4 is a schematic diagram illustrating the principle of AC voltage detection using a voltage detector according to one embodiment of the present invention. Here, an example of AC voltage detection for a circuit CR that transmits AC voltage (e.g., AC 6.6kV) from a high-voltage substation in a higher-level system to a sub-substation in a lower-level system is described.

[0055] First, the worker presses the switch 26 of the voltage detector 1 to perform a self-test. After confirming that the voltage detector 1 is functioning correctly as a result of the self-test, the worker then holds the gripping part 21 of the voltage detector 1 and brings the detector element 24 of the detection unit 23 close to the circuit CR in order to electrically connect the circuit CR and the detection unit 23. This causes the voltage detector 1 to operate in detection mode, and the AC level detection unit 237 can detect the minute current flowing from the circuit CR through the detection unit 23 and the ground-to-ground stray capacitance C0 of the detection unit 23 to the earth. If the voltage detector 1 does not detect a minute current, the light-emitting part 25a (e.g., red LED) of the notification unit 25 will not flash, and the sound-emitting part 25c will not sound. However, if a minute current is detected, the light-emitting part 25a will flash, and the sound-emitting part 25c will sound. In this way, the worker can confirm the AC charging state of the circuit CR.

[0056] Figure 5 is a schematic diagram illustrating the principle of DC voltage detection using a voltage detector according to one embodiment of the present invention. Here, the circuit CR is assumed to be a circuit that transmits a direct current (e.g., DC 1.5kV).

[0057] The worker connects the grounding wire 4 to the main body 2 of the voltage detector 1, and then connects the grounding wire 4 to the grounding terminal. In the example shown in the figure, the main body 2 of the voltage detector is shown to be grounded to the grounding terminal E via the power box 3, but inside the power box 3, the power supply 31 is bypassed, so it is equivalent to the main body 2 of the voltage detector being grounded.

[0058] Next, the worker, after the self-test, holds the gripping part 21 of the voltage detector 1 and touches the detector 24 of the voltage detection unit 23 to the circuit CR, thereby electrically connecting the circuit CR and the voltage detection unit 23. As a result, the voltage detector 1 operates in voltage detection mode and detects the minute current flowing through the closed circuit formed by the circuit CR and the voltage detection unit 23 via the grounding terminal using the DC level detector 238. If the voltage detector 1 does not detect a minute current, the light-emitting part 25b (orange LED) of the notification unit 25 does not flash, and the sound-emitting part 25c does not sound. However, if a minute current is detected, the light-emitting part 25b flashes and the sound-emitting part 25c sounds. In this way, the worker can confirm the DC charging state of the circuit CR.

[0059] Figure 6 is a diagram illustrating the principle of short-circuit condition determination using a voltage detector according to one embodiment of the present invention. Figure (a) shows a state in which the short-circuit grounding device SCG between the circuit CR and the grounding electrode terminal E is not left (removed) in the electrical equipment (e.g., sub-substation equipment), and Figure (b) shows a state in which the short-circuit grounding device SCG between the circuit CR and the grounding electrode terminal E is left (not removed) in the electrical equipment. The principle of short-circuit condition determination basically uses the principle of DC voltage detection. Therefore, by making only minor changes and / or additions to the configuration of the conventional DC voltage detection unit, it becomes possible to determine the short-circuit condition. For safety reasons, it is desirable that the short-circuit condition determination work be performed after the voltage detection described above.

[0060] First, as shown in Figure (a), the worker connects the main body 2 of the voltage detection unit and the power box 3 using the connecting wire 5, and also connects the power box 3 to the grounding terminal E of the electrical equipment using the grounding wire 4. In this state, the worker switches the power switch 33 of the power box 3 to the power supply 31 side, operates the voltage detector 1 in short-circuit detection mode, and electrically connects the detector 24 to the circuit CR. In this case, since the short-circuit grounding device SCG has been removed, the voltage detector 1 cannot detect a response signal, and the notification unit 25 is not driven.

[0061] On the other hand, as shown in Figure (b), with the short-circuit grounding device SCG still installed between the circuit CR and the grounding electrode terminal, the worker switches the power switch 33 of the power box 3 to the power supply 31 side and electrically connects the detector 24 to the circuit CR. In this case, the circuit CR and the voltage detector 1 form a virtual closed circuit via the ground, so a predetermined DC voltage is applied to the grounding electrode terminal E, and a small current (response signal) flows through the circuit CR. The voltage detector 1 receives this from the detector 24, and when it detects it with the DC level detector 238, it flashes the light-emitting parts 25a and 25b of the notification unit 25 alternately and sounds the sound-emitting part 25c. This allows the worker to recognize the short-circuit state of the circuit CR.

[0062] As described above, according to this embodiment, an operator can use a single voltage detector 1 to detect the charge state of the circuit CR and determine if the circuit CR is short-circuited due to the short-circuit grounding device SCG being left in place (forgotten to remove), thereby preventing ground fault accidents. In particular, according to this embodiment, since a configuration is adopted in which a short-circuit condition determination function is incorporated into the conventional voltage detector, an operator can perform the short-circuit condition determination work with simple operations similar to those of a familiar voltage detector, and can safely perform the short-circuit condition determination work within a range corresponding to the dielectric strength of the voltage detector 1. Furthermore, according to this embodiment, since the voltage detector 1 uses the circuit for DC voltage detection for short-circuit condition determination as well, the complexity of the circuit configuration can be avoided and manufacturing costs can be reduced.

[0063] <Second Embodiment> Figure 7 shows an example of a functional model of a voltage detector according to another embodiment of the present invention. As shown in the figure, the voltage detector 1 of this embodiment differs from that of the above embodiment in that it further comprises an operation mode control unit 2310.

[0064] The operation mode control unit 2310 controls whether the voltage detector 1 operates in voltage detection mode or short-circuit detection mode. The operation mode control unit 2310 includes, for example, a register that holds a flag indicating which mode the voltage detector 1 is operating in.

[0065] Specifically, the operation mode control unit 2310 controls the voltage detection unit 23 to operate in voltage detection mode only when the power box 3 is not connected to the voltage detection unit body 2, or when the power switch 33 is in a non-conductive state (OFF) even if the power box 3 is connected, and a self-test has been performed. As a result, the operator cannot perform voltage detection work until they have pressed the switch 26 to perform a self-test and confirmed that the voltage detector 1 is working correctly.

[0066] Furthermore, the operation mode control unit 2310 controls the voltage detection unit 23 to operate in short-circuit condition determination mode only if it determines that the power switch 33 of the power box 3 connected to the voltage detection unit body 2 is in a conductive state (ON) after the voltage detection unit 23 has operated in voltage detection mode. As a result, the operator cannot perform short-circuit condition determination work until after the voltage detection work has been performed in voltage detection mode.

[0067] As described above, this embodiment can achieve the same effects and advantages as the above embodiment. In particular, with this embodiment, the worker cannot perform the voltage detection work until they have pressed the switch 26 to perform a self-test and confirmed that the voltage detector 1 is functioning normally. This guides the worker to the correct voltage detection procedure and prevents them from mistakenly recognizing the charge state of the circuit CR due to inaccurate operation caused by a malfunction of the voltage detector 1 (e.g., dead battery). Furthermore, the worker cannot perform the short-circuit condition determination work until they have performed the voltage detection work in voltage detection mode. This guides the worker to the correct short-circuit condition determination procedure and prevents work errors such as accidentally touching the grounded voltage detector 1 to a circuit CR that is in a charged state. Moreover, this embodiment can contribute to the creation of sustainable infrastructure through safe electrical work in such electrical equipment using the voltage detector 1.

[0068] The embodiments described above are illustrative examples for illustrating the present invention and are not intended to limit the invention to these embodiments only. The present invention can be implemented in various forms without departing from its spirit.

[0069] For example, in the methods disclosed herein, steps, operations, or functions may be performed in parallel or in different orders, as long as this does not result in a contradiction in the outcome. The steps, operations, and functions described are provided merely as examples, and some of the steps, operations, and functions may be omitted, combined with each other to form a single unit, or other steps, operations, or functions may be added, without departing from the spirit of the invention.

[0070] Furthermore, although various embodiments are disclosed herein, specific features (technical matters) in one embodiment can be added to or replaced in other embodiments, with appropriate modifications, and such forms are also included in the gist of the present invention. [Explanation of Symbols]

[0071] 1...Voltage detector 2…Main body of the voltage detection unit 21...Gripping part 22... Insulating rod 23... Voltage detection unit 231...Main unit power 232... Limiting resistor 233...Measuring resistor 234... Capacitor 235...AC operating threshold adjustment unit 236...DC operating threshold adjustment unit 237...AC level detection unit 238...DC level detection unit 239... Notification Control Unit 2310...Operation Mode Control Unit 24... Detector 3…Power box 31…Power supply 32…Socket 33... Power switch 4...Ground wire 41...Grounding clip, 42...Ring plug 5…Connecting wires 51… Pin plug, 52… Pin plug CR…Electric circuit SCG… Short-circuit grounding device

Claims

1. A voltage detector for detecting the charge state of an electrical circuit, A voltage detection unit having a conductive detector, which detects the charge state of an electrical circuit by electrically connecting the detector to the circuit to be detected in voltage detection mode, The system includes a grounding wire that can be connected to a grounding electrode terminal provided in the electrical equipment into which the circuit is drawn, and a short-circuit determination unit that determines the short-circuit state based on the conductivity between the detector electrically connected to the circuit and the grounding electrode terminal in the short-circuit determination mode, The short-circuit determination unit determines a short-circuit state between the circuit and the grounding electrode terminal in the electrical equipment based on the response signal transmitted via the detector when a predetermined DC voltage is applied to the grounding electrode terminal. Voltage detector.

2. The grounding terminal is equipped with a power supply for applying the predetermined DC voltage, When the predetermined DC voltage is applied from the power supply to the grounding terminal, the system operates in the short-circuit detection mode. The voltage detector according to claim 1.

3. The system further includes a notification unit that operates to notify the outside in a manner that indicates at least visually and / or audibly recognizable voltage detection, depending on the charging state of the circuit. When the notification unit determines that a short circuit is occurring, it operates to notify in a manner that indicates a short circuit in a way that is different from the manner that indicates the voltage detection, and / or is recognizable by sound. The voltage detector according to claim 2.

4. The short-circuit determination unit is, When the response signal exceeds a predetermined operating threshold, a short-circuit detection signal is output. The notification unit operates to notify in a manner indicating the short-circuit state based on the short-circuit detection signal. The voltage detector according to claim 3.

5. The aforementioned voltage detection unit is An AC voltage detection unit for detecting the AC charging state of the aforementioned circuit, The system includes a DC voltage detection unit for detecting the DC charging state of the aforementioned circuit. The voltage detector according to claim 4.

6. The short-circuit detection unit determines the short-circuit state based on the response signal transmitted via the DC detection unit when the predetermined DC voltage is applied. The voltage detector according to claim 5.

7. The DC detection unit includes a voltage divider circuit for determining the predetermined operating threshold. The voltage detector according to claim 6.

8. The voltage divider circuit is set such that the predetermined operating threshold is lower than the specified operating threshold required for the DC voltage detection unit to detect the DC charge state of the circuit. The voltage detector according to claim 7.

9. The short-circuit detection unit outputs the short-circuit detection signal when the voltage of the response signal exceeds at least 5V set by the voltage divider circuit when the predetermined DC voltage of 9V is applied to the ground terminal from the power supply. The voltage detector according to claim 8.

10. The system further includes an operating mode control unit that controls which of the above-mentioned voltage detection mode and the above-mentioned short-circuit detection mode the system operates in. The operation mode control unit controls the operation so that the voltage detection unit operates in the voltage detection mode and then operates in the short-circuit determination mode. A voltage detector according to any one of claims 1 to 9.

11. A method for determining a short-circuit condition in electrical equipment to which an electrical circuit is connected, using a voltage detector that detects the charge state of an electrical circuit, The voltage detector comprises a voltage detection unit having a conductive detector, which detects the charge state of an electrical circuit by electrically connecting the detector to the circuit to be detected in voltage detection mode, and a short-circuit detection unit having a grounding wire connectable to a grounding terminal provided in the electrical equipment, which determines the short-circuit state based on the conductivity between the detector electrically connected to the circuit and the grounding terminal in short-circuit detection mode. In the short-circuit detection mode, with the detector of the voltage detector electrically connected to the circuit and the grounding wire electrically connected to the grounding electrode terminal, a predetermined DC voltage is applied from the voltage detector to the grounding electrode terminal. The short-circuit detection unit receives a response signal based on the applied predetermined DC voltage, Based on the received response signal, the short-circuit condition between the circuit and the grounding terminal in the electrical equipment is determined, This includes, when it is determined that a short circuit is occurring, notifying the outside in a manner that is visually and / or audibly recognizable, Method for determining a short circuit condition.

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