Test Equipment

Abstract

To provide a testing device capable of appropriately grasping a state of an electric circuit.SOLUTION: When testing a bus-bar linkage circuit 105 for linking a first bus 101 and a second bus 102 both having a three-phase electric circuit, a testing device 170 is allowed to include a transformer 134 in which a primary winding 134a is connected to the first bus-bar 101 and a secondary winding 134b that is connected in a Y connection and has neutral grounding is connected to the bus-bar linkage circuit 105, a current sensor 136 measuring test currents Ia, Ib, Ic flowing through each phase of the bus-bar linkage circuit 105 from the secondary winding 134b when testing the bus-bar linkage circuit 105, and a determination circuit 200 determining presence or absence of an abnormal state in the bus-bar linkage circuit 105 on the basis of a measurement result of the current sensor 136.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a test device. [Background technology]

[0002] As background art in this technical field, the abstract of Patent Document 1 listed below states, "[Problem] To provide an open-phase detection system, open-phase detection device, and open-phase detection method that can mechanically detect one-phase open faults that do not involve ground faults or short circuits, regardless of the equipment configuration or load status. [Solution] An open-phase detection system in an embodiment includes a three-phase stationary induction electric device, a current detector, an extraction unit, and a determination unit. The three-phase stationary induction electric device has a primary circuit in which an excitation current flows in the wiring for each phase. The current detector detects the excitation current of each phase of the primary circuit. The extraction unit extracts harmonics from the excitation current detected by the current detector. The determination unit determines whether the wiring of the primary circuit, which is the source of the excitation current detection, is in an open state or a connected state, depending on whether harmonics have been extracted by the extraction unit." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-028501 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned technology, there is a demand for more accurate understanding of the state of the electrical circuit. The present invention has been made in view of the above circumstances, and has as its object to provide a testing device that can appropriately grasp the state of an electrical circuit. [Means for solving the problem]

[0005] In order to solve the above problems, the testing device of the present invention is characterized in that, when testing a busbar tie circuit connecting a first busbar and a second busbar, both of which have three-phase electrical circuits, it comprises: a transformer whose primary winding is connected to the first busbar and whose secondary winding, which is Y-connected and neutral-grounded, is connected to the busbar tie circuit; a current sensor that measures the test current flowing from the secondary winding to each phase of the busbar tie circuit when testing the busbar tie circuit; and a judgment circuit that judges whether or not there is an abnormal state in the busbar tie circuit based on the measurement results of the current sensor. [Effects of the Invention]

[0006] According to the present invention, the state of an electrical circuit can be properly grasped. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a block diagram of a power distribution system according to a first embodiment. [Figure 2] FIG. 2 is a block diagram of a determination circuit. [Figure 3] FIG. 10 is a block diagram of a power distribution system according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Prerequisites for the embodiment] In the power supply systems of nuclear power plants, new regulatory standards require that power be shared between separate independent power supply systems or with other power supply systems. For this reason, it is planned to install busbar tie circuits between the main power supply systems. When using busbar tie circuits, it is common to check whether the busbar tie circuit can be used or not, taking into consideration the situation on-site, and then connect the circuit.

[0009] However, in the event of a disaster, even on-site inspections pose significant risks and increase the possibility of secondary disasters. While continuous monitoring systems have been developed in recent years, dielectric strength tests using voltages expected in actual operation are required to determine whether they are safe to use. However, preparing such equipment during a disaster is difficult. Even if test equipment were available, if its capacity is too large, a short-circuit current may flow simultaneously with the application of voltage if a fault occurs in the busbar connection circuit. Such a short-circuit current can cause large voltage fluctuations on the power supply side, potentially causing power outages and other adverse effects on equipment already connected to the power supply.

[0010] In view of the above-mentioned problems, in the embodiment described below, the soundness of the electric circuit is evaluated by applying a test voltage to the electric circuit using a dedicated test circuit constructed in advance. This makes it possible to evaluate the dielectric strength performance and to evaluate whether there are any problems in the use of the busbar tie circuit in the event of a disaster or the like, without going to the site.

[0011] [First embodiment] <Configuration of the first embodiment> FIG. 1 is a block diagram of a power distribution system 10 according to the first embodiment. 1, the power distribution system 10 includes a bus 101 (first bus), a bus 102 (second bus), a bus tie circuit 105, circuit breakers 109 and 110, test circuits 130 and 150, and a determination circuit 200. Of these, the test circuits 130 and 150 and the determination circuit 200 are collectively referred to as a "test device 170."

[0012] The busbars 101, 102 and the busbar tie circuit 105 each have a three-phase electric circuit. The busbar tie circuit 105 has a parasitic capacitance C in each phase. Power is supplied to the busbar 101 from the upper power supply 30 via a circuit breaker 32. The circuit breaker 109 opens and closes the busbar tie circuit 105 and the busbar 101. Similarly, the circuit breaker 110 opens and closes the busbar tie circuit 105 and the busbar 102.

[0013] The test circuit 130 includes circuit breakers 132 and 138, a transformer 134, and a current sensor 136. The transformer 134 includes a primary winding 134a and a secondary winding 134b. The secondary winding 134b is Y-connected, with its neutral point grounded. The circuit breaker 132 switches between the primary winding 134a and the busbar 101. The circuit breaker 138 switches between the secondary winding 134b and the busbar tie circuit 105. The phases of the secondary winding 134b are called phase A, phase B, and phase C (not shown), and the currents of the respective phases that flow through the busbar tie circuit 105 during testing of the busbar tie circuit 105 are called test currents Ia, Ib, and Ic. The current sensor 136 measures the current values ​​of these test currents Ia, Ib, and Ic.

[0014] The test circuit 150 also includes circuit breakers 152 and 158 and a transformer 154. The transformer 154 includes a primary winding 154a and a secondary winding 154b, and is configured similarly to the transformer 134. Here, the secondary winding 154b is a Y-connection, and its neutral point is grounded. The circuit breaker 152 switches between the primary winding 154a and the busbar 101. The circuit breaker 158 switches between the secondary winding 154b and the busbar connecting circuit 105.

[0015] The determination circuit 200 determines whether the busbar tie circuit 105 is normal or not based on the measurement result of the current sensor 136. In the illustrated example, since it is assumed that power is shared from the busbar 101 to the busbar 102, the test circuit 150 is not provided with anything equivalent to the current sensor 136. However, the test circuit 150 may also be provided with a current sensor similar to the current sensor 136.

[0016] When a predetermined normal operating voltage (normal voltage) is applied to the bus 101 and the circuit breakers 132 and 138 are closed, the secondary winding 134b of the transformer 134 applies a phase voltage of the test voltage Vtest [V] to the bus tie circuit 105. The transformer capacitance of each of the transformers 134 and 154 is preferably set to a value equivalent to the power output when charging and discharging the parasitic capacitance C [F]. In other words, if the angular frequency of the test voltage Vtest is ω [rad / s], the capacitance of the transformers 134 and 154 is expressed as follows: ω·C·Vtest 2 It is preferable to set it to "[VA]".

[0017] However, since transformers with this exact capacity are generally not commercially available, the capacity of transformers 134 and 154 is calculated as "K·ω·C·Vtest 2 It is preferable to set the constant K to "[VA]". Here, the constant K is an arbitrary value in the range of "1.0 to 100.0", for example, and is preferably as small as possible within that range. In the following description, "X to Y" means "greater than or equal to X and less than or equal to Y". It is more preferable that the constant K is in the range of "1.0 to 10.0", and even more preferably in the range of "1.0 to 2.0". The reason for this is that, assuming a situation in which a short circuit occurs in the busbar tie circuit 105, the smaller the constant K, the more the test currents Ia, Ib, and Ic flowing from the busbars 101 and 102 to the transformer 134 can be suppressed.

[0018] During normal operation, circuit breakers 109 and 110 are both open, and circuit breakers 132, 138, 152, and 158 in test circuits 130 and 150 are also open. When testing the busbar tie circuit 105, circuit breakers 132 and 138 in test circuit 130 and circuit breaker 158 in test circuit 150 are closed. This causes test voltage Vtest to be applied to the busbar tie circuit 105 via transformer 134. Note that circuit breaker 152 on the test circuit 150 side is provided to isolate the test circuit 150, and therefore may be left open.

[0019] The test voltage Vtest applied to the busbar tie circuit 105 is preferably a dielectric strength test voltage for each voltage class. For example, if the normal operating voltage (normal voltage) of the busbars 101, 102 and the busbar tie circuit 105 is 6.6 kV, the test voltage Vtest is preferably set higher, at about 10 kV. However, the test voltage Vtest may be the normal operating voltage (normal voltage) as long as it can confirm the soundness of the busbar tie circuit 105.

[0020] If the busbar tie circuit 105 is normal (no short circuit or the like has occurred), when the test voltage Vtest is applied to the busbar tie circuit 105 via the transformer 134, test currents Ia, Ib, and Ic corresponding to the charging and discharging current of the parasitic capacitance C flow through the busbar tie circuit 105. Note that an excitation current also flows through the secondary winding 154b of the transformer 154 via the busbar tie circuit 105, but this excitation current is small enough to be ignored.

[0021] As described above, the current sensor 136 measures the current values ​​of the test currents Ia, Ib, and Ic flowing through the busbar tie circuit 105. The determination circuit 200 determines whether these current values ​​are normal and notifies the user of the result. If the user confirms that the current values ​​are normal based on the notification from the determination circuit 200, the user opens the circuit breakers 132 and 158 to disconnect the test circuit 130 from the busbar 101 and the busbar tie circuit 105. After that, when the user closes the circuit breakers 109 and 110, the busbars 101 and 102 are connected via the busbar tie circuit 105. If any of the current values ​​measured by the current sensor 136 is abnormal, the determination circuit 200 notifies the user of this by an alarm or the like. This allows the user to recognize that the busbar tie circuit 105 cannot be used.

[0022] FIG. 2 is a block diagram of the determination circuit 200. 2, the judgment circuit 200 includes a short circuit / ground fault judgment unit 210, an open circuit judgment unit 220, and an OR circuit 230. The short circuit / ground fault judgment unit 210 includes comparison circuits 211, 212, and 213, and an OR circuit 214. The comparison circuit 211 outputs a “1” signal when the test current Ia is larger than the threshold value Th1 (=ω·C·Vtest·α) (when the test current Ia is too large), and outputs a “0” signal otherwise.

[0023] A case where the test current Ia is too large generally occurs when a short circuit occurs between phase A and another phase in the busbar connection circuit 105, or when a ground fault occurs in phase A. Here, the coefficient α is a coefficient applied to prevent malfunctions due to current detection accuracy, etc., and is preferably set to a value slightly larger than 1. For example, the coefficient α is preferably set in the range of 1.005 to 2.000, more preferably in the range of 1.005 to 1.050, and even more preferably in the range of 1.005 to 1.015.

[0024] Similarly, the comparison circuits 212 and 213 each output a "1" signal if the test currents Ib and Ic are greater than the threshold value Th1, and output a "0" signal otherwise. The OR circuit 214 outputs the logical sum of the output signals of the comparison circuits 211, 212, and 213. Therefore, the OR circuit 214 outputs a "1" signal if any of the test currents Ia, Ib, and Ic is greater than the threshold value Th1, i.e., if a short circuit or ground fault has occurred somewhere in the busbar tie circuit 105, and outputs a "0" signal otherwise.

[0025] The disconnection determination unit 220 includes comparison circuits 221, 222, and 223, and an OR circuit 224. The comparison circuit 221 outputs a “1” signal when the test current Ia is smaller than the threshold value Th2 (=ω·C·Vtest·β) (when the test current Ia is too small), and outputs a “0” signal otherwise.

[0026] A case where the test current Ia is too small generally occurs when a break occurs in the A phase of the busbar tie circuit 105. Here, like the coefficient α described above, the coefficient β is also a coefficient applied to prevent malfunctions due to the accuracy of current detection, etc., and is preferably set to a value slightly smaller than "1." For example, the coefficient α is preferably set in the range of "0.700 to 0.995," more preferably in the range of "0.950 to 0.995," and even more preferably in the range of "0.985 to 0.995."

[0027] Similarly, the comparison circuits 222 and 223 each output a "1" signal if the test currents Ib and Ic are smaller than the threshold value Th2, and output a "0" signal otherwise. The OR circuit 224 outputs the logical sum of the output signals of the comparison circuits 221, 222, and 223. Therefore, the OR circuit 224 outputs a "1" signal if any of the test currents Ia, Ib, and Ic is smaller than the threshold value Th2, i.e., if a break has occurred at any point in the busbar tie circuit 105, and outputs a "0" signal otherwise.

[0028] The OR circuit 230 outputs the logical sum of the output signals of the OR circuits 214 and 224 as an alarm signal SJ. Therefore, the alarm signal SJ becomes "1" when a short circuit, a ground fault, or a disconnection occurs anywhere in the busbar tie circuit 105, and becomes "0" in all other cases. As a result, when the alarm signal SJ is "1," the user can be notified that some abnormality has occurred in the busbar tie circuit 105 by, for example, outputting an alarm sound from a buzzer (not shown) or turning on a warning light (not shown).

[0029] [Second embodiment] 3 is a block diagram of a power distribution system 20 according to the second embodiment. In the following description, parts corresponding to those in the first embodiment described above are given the same reference numerals, and their description may be omitted. 3, the power distribution system 20 includes bus bars 101 and 102, a bus bar connecting circuit 105, circuit breakers 109 and 110, test circuits 130 and 150, and a determination circuit 200, similar to the power distribution system 10 of the first embodiment (see FIG. 1).

[0030] Furthermore, the power distribution system 20 includes a circuit breaker 172 and a connector 174 connected to the busbar 102 via the circuit breaker 172. An emergency power supply device 301 is connected to the connector 174 as needed. The emergency power supply device 301 is, for example, a small-scale portable power supply device. In this embodiment, a current sensor 156 is connected to the secondary winding 154b of the transformer 154. Similar to the current sensor 136, the current sensor 156 measures the test currents Ia, Ib, and Ic of each phase flowing from the secondary winding 154b to the busbar tie circuit 105.

[0031] In this embodiment, when the power supply from the upper power supply 30 to the bus bar 101 is cut off, the emergency power supply device 301 is connected to the bus bar 102, and power can be supplied from the bus bar 102 to the bus bar 101 via the bus bar tie circuit 105. Before this power supply is performed, it is possible to test whether the bus bar tie circuit 105 is normal or not using the test circuit 150 and the determination circuit 200, in the same manner as described for the test circuit 130.

[0032] [Effects of the embodiment] As described above, according to the embodiment, the test device 170 includes a transformer 134 having a primary winding 134a connected to the first bus (101) and a secondary winding 134b connected in a Y-connection and grounded at the neutral point and connected to the bus tie circuit 105 when testing the bus tie circuit 105, which connects the first bus (101) and the second bus (102), both of which have three-phase electrical circuits; a current sensor 136 that measures test currents Ia, Ib, and Ic that flow from the secondary winding 134b to each phase of the bus tie circuit 105 when testing the bus tie circuit 105; and a determination circuit 200 that determines whether or not an abnormal state exists in the bus tie circuit 105 based on the measurement results of the current sensor 136.

[0033] In this way, the secondary winding 134b connected to the busbar tie circuit 105 is Y-connected with the neutral point grounded, so if a short circuit or ground fault occurs in any phase of the busbar tie circuit 105, significant changes will appear in the test currents Ia, Ib, and Ic, which will allow the state of the electrical circuit to be properly understood.

[0034] Furthermore, it is more preferable that the busbar connection circuit 105 has a parasitic capacitance C in each phase, and the determination circuit 200 determines whether or not an abnormal state, such as a short circuit, a ground fault, or an open circuit, exists in the busbar connection circuit 105 based on the result of comparing the measurement result of the current sensor 136 with threshold values ​​(Th1, Th2) corresponding to the parasitic capacitance C. This makes it possible to detect various abnormal states in the busbar connection circuit 105 with a simple circuit configuration that compares the measurement result of the current sensor 136 with the threshold values ​​(Th1, Th2).

[0035] The capacity of the transformer 134 is expressed as K·ω·C·Vtest, where Vtest [V] is the phase voltage output from the secondary winding 134b when testing the busbar tie circuit 105, ω [rad / s] is the angular frequency of the phase voltage, C [F] is the parasitic capacitance of each phase, and K is a constant between 1.0 and 100.0. 2 [VA] is even more preferable.

[0036] In this way, by setting the capacitance of the transformer 134 to a value close to the power when charging and discharging the parasitic capacitance C, the impedance of the transformer 134 as seen from the first bus (101) can be made sufficiently high. As a result, even if a short-circuit fault occurs in the busbar tie circuit 105, the short-circuit current flowing from the first busbar (101) to the busbar tie circuit 105 via the transformer 134 can be suppressed to a relatively low value. As a result, voltage fluctuations in the first busbar (101) are suppressed, and even if there is a device receiving power from the first busbar (101), a situation in which the device stops can be suppressed. In particular, even in a case in which an emergency power supply device 301 or the like with a small power capacity is connected as in the second embodiment, voltage fluctuations in the emergency power supply device 301 or the like can be suppressed.

[0037] Furthermore, it is more preferable that the determination circuit 200 determines that an abnormal state has occurred in the busbar tie circuit 105 when the test currents Ia, Ib, Ic in any phase of the current sensor 136 are greater than ω·C·Vtest·α, where α is a constant in the range of 1.005 to 2.000. This makes it possible to determine that an abnormal state has occurred in the busbar tie circuit 105 when a short circuit or a ground fault occurs in the busbar tie circuit 105.

[0038] Furthermore, it is more preferable that the determination circuit 200 determines that an abnormal state has occurred in the busbar tie circuit 105 when the test currents Ia, Ib, Ic in any phase of the current sensor 136 are smaller than ω·C·Vtest·β, where β is a constant in the range of 0.700 to 0.995. This makes it possible to determine that an abnormal state has occurred in the busbar tie circuit 105 when a break occurs in the busbar tie circuit 105.

[0039] [Variations] The present invention is not limited to the above-described embodiments and various modifications are possible. The above-described embodiments are provided as examples to facilitate understanding of the present invention and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to delete part of the configuration of each embodiment, or to add or replace other configurations. Furthermore, the control lines and information lines shown in the figures are those considered necessary for explanation, and do not necessarily represent all control lines and information lines necessary for the product. In reality, it is acceptable to consider that almost all components are interconnected. Possible modifications of the above-described embodiments include, for example, the following:

[0040] (1) In each of the above embodiments, the judgment circuit 200 detects a short circuit and a ground fault in the busbar connection circuit 105 without making any particular distinction between them. However, if it is desired to distinguish between a short circuit and a ground fault, the presence or absence of a ground fault may be detected based on the current flowing from the neutral point of the secondary windings 134b and 154b or the total current of the test currents Ia, Ib, and Ic. [Explanation of symbols]

[0041] 101 busbar (first busbar) 102 busbar (second busbar) 105 Busbar connection circuit 134 Transformer 134a Primary Winding 134b Secondary winding 136 Current Sensor 170 Test Equipment 200 Judgment circuit C parasitic capacitance Ia test current Th1 threshold Th2 threshold Ib,Ic test current Ia, Ib, Ic test current

Claims

1. a transformer having a primary winding connected to the first bus and a secondary winding connected to the bus connection circuit, the secondary winding being Y-connected and neutral-grounded, when testing a bus connection circuit connecting a first bus and a second bus, both of which have three-phase current paths; a current sensor for measuring a test current flowing from the secondary winding to each phase of the busbar connection circuit when testing the busbar connection circuit; a determination circuit that determines whether or not an abnormal state exists in the busbar connection circuit based on the measurement result of the current sensor. A test device characterized by:

2. The busbar connecting circuit has a parasitic capacitance in each phase, The determination circuit determines whether or not the abnormal state, such as a short circuit, a ground fault, or a break, exists in the busbar connection circuit based on a comparison result between the measurement result of the current sensor and a threshold value corresponding to the parasitic capacitance.

2. The test device according to claim 1.

3. The capacity of the transformer is expressed as K·ω·C·Vtest, where Vtest [V] is the phase voltage output from the secondary winding when testing the busbar tie circuit, ω [rad / s] is the angular frequency of the phase voltage, C [F] is the parasitic capacitance of each phase, and K is a constant between 1.0 and 100.

0. 2 [VA] 3. The test device according to claim 2.

4. The determination circuit determines that the abnormal state has occurred in the busbar tie circuit when the test current in any phase of the current sensor is greater than ω·C·Vtest·α, where α is a constant in the range of 1.005 to 2.

000.

4. The test device according to claim 3.

5. The determination circuit further determines that the abnormal state has occurred in the busbar tie circuit when the test current in any phase of the current sensor is smaller than ω·C·Vtest·β, where β is a constant in the range of 0.700 to 0.

995.

5. The test device according to claim 4.

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