Vacuum circuit breaker arc extinguishing ability detection device

Abstract

The present invention discloses a device for detecting the arc extinguishing capability of a vacuum circuit breaker, comprising a DC high-voltage generator, a DC high-current generator, a storage oscilloscope, a current-limiting resistor R1, a current-limiting resistor R2, an isolation diode D1, an isolation diode D2, a freewheeling diode D4, a current-stabilizing inductor L, a transient voltage suppressor diode D3, and an ultraviolet laser. The device cleverly utilizes changes in electrical quantities injected by DC current and draws on laser technology to intuitively and sensitively reflect the arc extinguishing capability of the circuit breaker using a very low test power. The test method is simple, low-cost, innovative in principle, and highly practical. It enables direct, on-site detection of the short-circuit breaking capability of the circuit breaker using a portable detection instrument, overcoming the significant energy consumption associated with detecting the arc extinguishing capability of the circuit breaker and minimizing damage to the equipment being tested.

Description

Technical Field

[0001] The present invention relates to the field of power equipment detection, and in particular to a device for detecting arc extinguishing capability of a vacuum circuit breaker. Background Art

[0002] Vacuum circuit breakers are widely used in distribution networks due to their small size, light weight, suitability for frequent operation, and maintenance-free arc extinguishing. However, during actual operation, abnormalities and even arc chamber explosions are not uncommon. This is particularly true for vacuum circuit breakers used to switch capacitors. Due to frequent operation, explosions caused by contact bounce, slow opening and closing of the mechanism, and vacuum leaks have repeatedly occurred.

[0003] Due to the small mechanical stroke of vacuum circuit breakers, preventive testing of their mechanical properties is difficult. For vacuum interrupters, it is difficult to detect the gas composition like SF6 circuit breakers. Therefore, even if vacuum leaks or internal arc decomposition products exceed the standard, they cannot be detected. Due to the structural characteristics of the vacuum circuit breaker itself, preventive testing of its breaking capacity and mechanical properties is difficult to carry out effectively.

[0004] Therefore, to date, the detection of the arc extinguishing characteristics of vacuum circuit breakers has remained at a very crude and primitive stage. It is only necessary to open and close the circuit several times to check whether the energy storage circuit is normal, the opening and closing time is normal, and the fracture withstand voltage and DC resistance are normal. If the arc contacts of the arc extinguishing chamber are worn, the vacuum leaks, or the pull rod is stuck due to friction, the above test items obviously cannot effectively reflect the actual arc extinguishing ability. However, the actual arc extinguishing ability has definitely decreased. It can be seen that the existing vacuum circuit breaker maintenance and testing standards still have great deficiencies. The hidden dangers of mechanical abnormalities and arc extinguishing ability degradation of circuit breakers are sometimes not discovered in a timely and effective manner. With the development of technology and the increasing requirements for condition-based maintenance, a technical method that can conveniently and effectively detect the arc extinguishing ability of vacuum circuit breakers, the most important primary equipment in power grids below 35kV, is urgently needed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a device for detecting the arc extinguishing ability of a vacuum circuit breaker, which can conveniently and effectively detect the arc extinguishing ability of the vacuum circuit breaker.

[0006] To solve the above technical problems, the present invention adopts a technical solution: providing a vacuum circuit breaker arc extinguishing ability detection device, including a DC high voltage generator, a DC high current generator, a storage oscilloscope, a current limiting resistor R1, a current limiting resistor R2, an isolation diode D1, an isolation diode D2, a freewheeling diode D4, a current stabilizing inductor L, a transient voltage suppressor diode D3, and an ultraviolet laser;

[0007] The positive electrode of the DC high-voltage output terminal of the DC high-voltage generator is connected in series with the current-limiting resistor R1 and the positive electrode of the isolation diode D1 in sequence; the positive electrode of the DC high-current output terminal of the DC high-current generator is connected in series with the current-limiting resistor R2 and the positive electrode of the isolation diode D2 in sequence; the isolation diode D1 is connected in parallel with the negative electrode of the isolation diode D2, and then connected in series with one end of a current-stabilizing inductor L, and the other end of the current-stabilizing inductor L is connected to one end of the interrupter of the vacuum circuit breaker under test; the two ends of the current-stabilizing inductor L are connected in parallel with the freewheeling diode D4; the negative electrode of the DC high-voltage output terminal of the DC high-voltage generator is connected in parallel with the negative electrode of the DC high-current output terminal of the DC high-current generator, and then connected to the other end of the interrupter of the vacuum circuit breaker under test; the two ends of the interrupter of the vacuum circuit breaker under test are connected in parallel with the transient voltage suppression diode D3, and are connected to an analog measurement channel of the storage oscilloscope; the other analog measurement channel of the storage oscilloscope is connected in parallel with the trip coil K of the vacuum circuit breaker under test;

[0008] The light outlet of the ultraviolet laser is arranged in the middle of the arc extinguishing chamber of the vacuum circuit breaker to be tested.

[0009] In a preferred embodiment of the present invention, the ultraviolet laser is connected to the light outlet via an insulating optical fiber.

[0010] Furthermore, the maximum output voltage of the DC high voltage generator is not less than 5KV.

[0011] Furthermore, the maximum output current of the DC high current generator is not less than 2KA.

[0012] Furthermore, the current-stabilizing inductor L is an iron core reactor with an air gap.

[0013] The beneficial effects of the present invention are:

[0014] (1) The present invention uses a portable detection instrument to directly detect the short-circuit breaking capacity of a circuit breaker on site. The existing technology for testing the short-circuit current breaking capacity of a circuit breaker requires a very large capacity detection instrument, which is difficult to use on site. As a result, many circuit breakers with insufficient arc extinguishing capacity cannot be discovered through intuitive detection methods, causing many power grid hidden dangers. The present invention allows such hidden dangers to be properly discovered, fundamentally avoiding the explosion risk caused by insufficient arc extinguishing capacity of the circuit breaker, and substantially improving the safety of the power grid;

[0015] (2) The present invention overcomes the huge energy consumption when testing the arc extinguishing ability of the circuit breaker. The arc extinguishing ability test of the circuit breaker must generally be tested under short-circuit conditions. The short-circuit test under the rated voltage of the high-voltage power equipment itself consumes huge energy and will also cause instantaneous impact on the power grid during the test. The energy consumption of a vacuum circuit breaker above 35KV in a single test is as high as dozens of degrees. The present invention cleverly uses DC instead of AC, so that only a few tenths of the test energy consumption under AC conditions is required to complete the same test, thereby greatly reducing the huge energy consumption of the circuit breaker arc extinguishing test;

[0016] (3) The present invention causes minimal damage to the equipment being tested. The existing technology must test the arc extinguishing ability of the circuit breaker under the short-circuit condition of the AC rated voltage. The strong arc burning in the short-circuit condition will cause varying degrees of damage to the arc extinguishing chamber of the circuit breaker. Generally, a high-voltage circuit breaker can only interrupt the short-circuit current dozens of times. Since the current and voltage of the test are relatively small, the capacity of the present invention to interrupt once is only equivalent to the daily interruption of the AC load current. Therefore, the damage to the arc extinguishing chamber of the circuit breaker under test is also minimal, and it can be considered that the effect of non-destructive testing has been achieved;

[0017] (4) The present invention significantly reduces the cost of testing the arc extinguishing capability of circuit breakers. Since the capacity of circuit breaker arc extinguishing capability testing equipment is as high as tens of megawatts and the equipment price is as high as millions of yuan, on-site testing is not possible. The present invention can use existing large current generators and high-voltage DC generators, combined with a few external components, which makes the total cost of the testing equipment only a few hundred yuan. Under the premise of reducing the testing cost by nearly 10,000 times, almost the same testing effect is achieved;

[0018] (5) The present invention utilizes ultraviolet radiation from an ultraviolet laser to irradiate the interior of the middle portion of the arc extinguishing chamber, which can very sensitively detect whether there is a hidden danger of gas leakage in the arc extinguishing chamber, and further more sensitively detect the hidden danger of reduced arc extinguishing ability of the circuit breaker. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The circuit diagram of the arc extinguishing ability detection device of the vacuum circuit breaker of the present invention is shown in FIG. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0021] See also Figure 1 , embodiments of the present invention include:

[0022] A device for detecting the arc extinguishing capability of a vacuum circuit breaker includes a DC high voltage generator 1, a DC high current generator 2, a storage oscilloscope 4, a current limiting resistor R1, a current limiting resistor R2, an isolation diode D1, an isolation diode D2, a freewheeling diode D4, a current stabilizing inductor L, a transient voltage suppression diode D3, and an ultraviolet laser 7.

[0023] The positive electrode of the DC high-voltage output terminal of the DC high-voltage generator 1 is connected in series with the current-limiting resistor R1 and the positive electrode of the isolation diode D1 in sequence; the positive electrode of the DC high-current output terminal of the DC high-current generator 2 is connected in series with the current-limiting resistor R2 and the positive electrode of the isolation diode D2 in sequence; the isolation diode D1 and the cathode of the isolation diode D2 are connected in parallel, and then connected in series with one end of a current-stabilizing inductor L, the other end of the current-stabilizing inductor L is connected to one end of the interrupter of the vacuum circuit breaker under test; the two ends of the current-stabilizing inductor L are connected in parallel with the freewheeling diode D4; the negative electrode of the DC high-voltage output terminal of the DC high-voltage generator 1 is connected in parallel with the negative electrode of the DC high-current output terminal of the DC high-current generator 2, and then connected to the other end of the interrupter of the vacuum circuit breaker under test; the two ends of the interrupter of the vacuum circuit breaker under test are connected in parallel with the transient voltage suppression diode D3, and are connected to an analog measurement channel of the storage oscilloscope 4; the other analog measurement channel of the storage oscilloscope 4 is connected in parallel with the trip coil K of the vacuum circuit breaker under test. The ultraviolet laser 7 emits a laser beam through the insulating optical fiber 6 and the light outlet 5. The light outlet 5 is placed in the middle of the arc extinguishing chamber of the vacuum circuit breaker to be tested.

[0024] Furthermore, the maximum output voltage of the DC high voltage generator 1 is not less than 5KV.

[0025] Furthermore, the maximum output current of the DC high current generator 2 is not less than 2KA.

[0026] Furthermore, the current-stabilizing inductor L is an iron core reactor with an air gap.

[0027] The present invention is a new arc-breaking capacity detection technology for vacuum circuit breakers based on low-energy DC simulated fault current. By injecting a DC current and voltage with controllable current and voltage between the circuit breaker contacts, when the circuit breaker contacts are closed, a large current flows. When the contacts are opened, the voltage at both ends instantly rises to a DC voltage close to the operating voltage. If the circuit breaker has normal arc extinguishing capacity, the large current should be able to be immediately interrupted. If the arc extinguishing capacity is insufficient, the large current will be re-interrupted by the high voltage between the contacts after it is disconnected. However, since the DC current and voltage are both controllable, their overall energy is relatively small and will not damage the arc extinguishing chamber. By using a low-energy DC simulated fault current, the arc extinguishing capacity of the circuit breaker can be very intuitively detected. DC is used instead of AC because it is much more difficult to interrupt a DC arc than an AC arc. In this way, the arc extinguishing capacity in an AC environment can be reflected by a smaller capacity DC current and voltage. The present invention cleverly uses the changes in the electrical quantities injected by the DC current to directly reflect the arc extinguishing capacity of the circuit breaker. The test method is simple, the principle is novel, and the practicality is strong.

[0028] When conditions permit, the most direct and effective method is to directly use a high-voltage AC power supply to inject a large current into the circuit breaker to test its arc extinguishing ability. However, this method requires extremely large equipment capacity and volume, because the energy required to directly generate a short-circuit fault is usually only available at the manufacturer. For on-site preventive testing, this solution is obviously unrealistic. However, when the DC current does not cross zero, the ability of a circuit breaker with the same mechanical structure to interrupt DC current is far lower than that of interrupting AC current. For low-voltage switches, the ratio of DC to AC breaking capacity is generally only 1:10. For high-voltage switchgear, it is generally around 1:100-1:1000. Therefore, if DC current is used instead of AC current, the same arc extinguishing ability test can be achieved with a few hundredths of the equipment capacity of the AC test equipment.

[0029] In order to further simulate the short-circuit current breaking characteristics of a real environment, the present invention adopts a method in which a DC current source and a voltage source work together. The DC high current generator 2 and the DC high voltage generator 1 are respectively connected to the two ends of the arc extinguishing chamber of the circuit breaker under test through current limiting resistors (R2, R1) and isolation diodes (D2, D1), and a DC high current and high voltage are applied at the same time. It can be seen from the circuit structure that during the closing of the circuit breaker contacts, the high voltage is all applied to the two ends of the current limiting resistor R1. Due to the presence of the current limiting resistor, neither power supply will be overloaded and damaged; when the circuit breaker is opened, the contacts are disconnected, and the DC arc generated by the high current generator acts on the two ends of the contacts. When the arc is extinguished, the high voltage of the high voltage generator is immediately applied to the two ends of the contacts. This instantaneous switching of high current and high voltage is very consistent with the characteristics of real operating conditions. If the arc extinguishing ability of the circuit breaker is normal, the large current should be able to be interrupted immediately. If the arc extinguishing ability is insufficient, the large current will be broken down and turned on again by the high voltage between the contacts after it is disconnected. However, since the DC current and voltage are both controllable, its overall energy is relatively small and will not damage the arc extinguishing chamber. By using low-energy DC to simulate the fault current, the arc extinguishing ability of the circuit breaker can be detected very intuitively.

[0030] The present invention also stabilizes the DC test current flowing through the circuit breaker, increases arc energy storage, and improves the difficulty of arc extinguishing by combining a current-stabilizing inductor L with a freewheeling diode D4, thereby further testing the arc extinguishing capability of the circuit breaker under extreme conditions. By storing the voltage change waveform at both ends of the circuit breaker break and the voltage of the circuit breaker tripping coil K on the oscilloscope 4, the current and voltage changes at the moment of circuit breaker tripping can be easily observed, and the arc burning time, arc extinguishing speed, and whether there is a current cutoff or restrike problem can be understood, thereby intuitively detecting the arc extinguishing capability of the circuit breaker.

[0031] In addition, the present invention also uses an ultraviolet laser, which uses the ultraviolet radiation of the ultraviolet laser 7 to irradiate the middle part of the arc extinguishing chamber. This can very sensitively detect whether there is a hidden danger of air leakage in the arc extinguishing chamber. Once a trace amount of air enters, the air is irradiated by the high-energy photons of the ultraviolet laser, which greatly reduces the electronic work function of the circuit breaker contacts. This can significantly reduce the arc extinguishing ability of the circuit breaker, thereby further more sensitively detecting the hidden danger of reduced arc extinguishing ability of the circuit breaker. The ultraviolet laser 7 emits a laser beam through the insulating optical fiber 6 and the light outlet 5. The light outlet 5 is placed in the middle of the arc extinguishing chamber of the vacuum circuit breaker under test. This completely isolates the laser system from the high-voltage electrical part being tested, avoiding damage to the laser equipment.

[0032] The present invention cleverly utilizes the change of electrical quantity injected by direct current and draws on laser technology to intuitively and sensitively reflect the arc extinguishing capability of the circuit breaker with very small test power. The test method is simple, the principle is novel and the practicability is strong.

[0033] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A vacuum circuit breaker arc extinguishing ability detection device, characterized in that: Including a DC high voltage generator, a DC high current generator, a storage oscilloscope, a current limiting resistor R1, a current limiting resistor R2, an isolation diode D1, an isolation diode D2, a freewheeling diode D4, a current stabilizing inductor L, a transient voltage suppression diode D3, and an ultraviolet laser; The positive electrode of the DC high-voltage output terminal of the DC high-voltage generator is connected in series with the current-limiting resistor R1 and the positive electrode of the isolation diode D1 in sequence; the positive electrode of the DC high-current output terminal of the DC high-current generator is connected in series with the current-limiting resistor R2 and the positive electrode of the isolation diode D2 in sequence; the isolation diode D1 is connected in parallel with the negative electrode of the isolation diode D2, and then connected in series with one end of a current-stabilizing inductor L, and the other end of the current-stabilizing inductor L is connected to one end of the interrupter of the vacuum circuit breaker under test; the two ends of the current-stabilizing inductor L are connected in parallel with the freewheeling diode D4; the negative electrode of the DC high-voltage output terminal of the DC high-voltage generator is connected in parallel with the negative electrode of the DC high-current output terminal of the DC high-current generator, and then connected to the other end of the interrupter of the vacuum circuit breaker under test; the two ends of the interrupter of the vacuum circuit breaker under test are connected in parallel with the transient voltage suppression diode D3, and are connected to an analog measurement channel of the storage oscilloscope; the other analog measurement channel of the storage oscilloscope is connected in parallel with the trip coil K of the vacuum circuit breaker under test; The light outlet of the ultraviolet laser is arranged in the middle of the arc extinguishing chamber of the vacuum circuit breaker to be tested.

2. The arc extinguishing capability detection device of a vacuum circuit breaker according to claim 1, characterized in that: The ultraviolet laser is connected to the light outlet via an insulating optical fiber.

3. The arc extinguishing capability detection device of a vacuum circuit breaker according to claim 1, characterized in that: The maximum output voltage of the DC high voltage generator is not less than 5KV.

4. The arc extinguishing capability detection device for vacuum circuit breaker according to claim 1, characterized in that: The maximum output current of the DC high current generator is not less than 2KA.

5. The arc extinguishing capability detection device of a vacuum circuit breaker according to claim 1, characterized in that: The current stabilizing inductor L is an iron core reactor with an air gap.

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