Vacuum circuit breaker short-circuit current breaking capacity detection device

Abstract

The present invention discloses a vacuum circuit breaker short-circuit current breaking capacity 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, and a transient voltage suppression diode D3. The present invention is a brand-new vacuum circuit breaker arc breaking capacity detection technology based on low-energy DC simulated fault current. Through low-energy DC simulated fault current, the arc extinguishing capacity of the circuit breaker can be detected very intuitively. The test method is simple, low-cost, novel in principle, and highly practical. It realizes the on-site direct detection of the short-circuit breaking capacity of the circuit breaker with a portable detection instrument, overcomes the huge energy consumption consumed in the operation of detecting the arc extinguishing capacity of the circuit breaker, and causes minimal damage to the tested equipment.

Description

Technical Field

[0001] The invention relates to the field of power equipment detection, and in particular to a device for detecting the short-circuit current breaking capacity of a vacuum circuit breaker. Background Art

[0002] Vacuum circuit breakers are widely used in distribution networks because of their small size, light weight, frequent operation, and arc extinguishing without maintenance. However, in actual operation, vacuum circuit breakers are prone to abnormalities or even arc extinguishing chamber explosions. This is especially true for vacuum circuit breakers used for switching capacitors. Frequent operation can cause contact bounce, slow opening and closing of the mechanism, and vacuum leakage, which can lead to explosions.

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

[0004] Therefore, up to now, the detection of arc extinguishing characteristics of vacuum circuit breakers is still at a very rough primitive stage. It is only necessary to check the energy storage circuit, opening and closing time, break withstand voltage and DC resistance after several opening and closing. If the arc contacts of the arc extinguishing chamber are worn, the vacuum leaks, and the pull rod is rubbed and stuck, the above detection items obviously cannot effectively reflect it. However, the actual arc extinguishing ability is definitely reduced. It can be seen that the existing vacuum circuit breaker repair and testing standards still have great deficiencies. The mechanical abnormalities and arc extinguishing ability reduction hazards of circuit breakers are sometimes not discovered in a timely and effective manner. With the development of technology and the increasing requirements for condition maintenance, a technical method that can conveniently and effectively detect the arc extinguishing ability of the most important vacuum circuit breaker in the primary equipment of the power grid 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 short-circuit current breaking capacity of a vacuum circuit breaker, which can conveniently and effectively detect the arc extinguishing capacity of the vacuum circuit breaker.

[0006] In order to solve the above technical problems, a technical solution adopted by the present invention is: to provide a vacuum circuit breaker short-circuit current breaking capacity 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, and a transient voltage suppression diode D3;

[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 arc extinguishing chamber break of the vacuum circuit breaker under test; both 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 arc extinguishing chamber break of the vacuum circuit breaker under test; both ends of the arc extinguishing chamber break 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 tripping coil K of the vacuum circuit breaker under test.

[0008] In a preferred embodiment of the present invention, the detection device further comprises an AM signal receiver, and a signal output terminal of the AM signal receiver is connected to a third analog quantity measurement channel of the storage oscilloscope.

[0009] Furthermore, the maximum output voltage of the DC high voltage generator is not less than 5KV.

[0010] Furthermore, the maximum output current of the DC high current generator is not less than 2KA.

[0011] Furthermore, the current-stabilizing inductor L is an iron core reactor with an air gap.

[0012] The beneficial effects of the present invention are:

[0013] (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 hazards. The present invention allows such hazards to be properly discovered, fundamentally avoiding the explosion hazard caused by insufficient arc extinguishing capacity of the circuit breaker, and substantially improving the safety of the power grid;

[0014] (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, and the short-circuit test of the high-voltage power equipment under the rated voltage itself consumes huge energy. During the test, it will also cause instantaneous impact on the power grid. 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 direct current instead of alternating current, so that only a few tenths of the test energy consumption under alternating current conditions is required to complete the same test, thereby greatly reducing the huge energy consumption of the circuit breaker arc extinguishing test;

[0015] (3) The present invention causes minimal damage to the equipment under test. The prior art must test the arc extinguishing capability of the circuit breaker under the short-circuit condition of the rated AC voltage. The strong arc burning under 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 of the present invention are relatively small, the capacity of the circuit breaker interrupted 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;

[0016] (4) The present invention achieves a significant reduction in the cost of circuit breaker arc extinguishing capability testing. Circuit breaker arc extinguishing capability testing equipment has a capacity of tens of megawatts and an equipment price of several million yuan, so 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a circuit principle diagram of a preferred embodiment of the short-circuit current breaking capacity detection device of the vacuum circuit breaker of the present invention;

[0018] Figure 2 It is a circuit schematic diagram of another preferred embodiment of the short-circuit current breaking capacity detection device of the vacuum circuit breaker of the present invention. DETAILED DESCRIPTION

[0019] The preferred embodiments of the present invention are described in detail below in conjunction with 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 definite definition of the protection scope of the present invention.

[0020] Embodiment 1:

[0021] See also Figure 1 A vacuum circuit breaker short-circuit current breaking capacity detection device 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, and a transient voltage suppression diode D3.

[0022] 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 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 arc extinguishing chamber break of the vacuum circuit breaker under test; both 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 arc extinguishing chamber break of the vacuum circuit breaker under test; both ends of the arc extinguishing chamber break 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; another analog measurement channel of the storage oscilloscope 4 is connected in parallel with the tripping coil K of the vacuum circuit breaker under test.

[0023] Furthermore, the maximum output voltage of the DC high voltage generator 1 is not less than 5KV.

[0024] Furthermore, the maximum output current of the DC high current generator 2 is not less than 2KA.

[0025] Furthermore, the current-stabilizing inductor L is an iron core reactor with an air gap.

[0026] The present invention is a brand-new arc breaking capacity detection technology for vacuum circuit breakers based on low-energy DC simulated fault current. By injecting controllable DC current and voltage between the contacts of the circuit breaker, when the contacts of the circuit breaker are closed, a large current is flowing. When the contacts are opened, the voltage at both ends instantly rises to a DC voltage close to the operating voltage. If the arc extinguishing capacity of the circuit breaker is normal, the large current should be able to be broken immediately. If the arc extinguishing capacity is insufficient, the large current will be broken down and turned on again by the high voltage between the contacts after the large current is disconnected. However, since the DC current and voltage are both controllable, the overall energy is small and the arc extinguishing chamber will not be damaged. By using low-energy DC simulated fault current, the arc extinguishing capacity of the circuit breaker can be detected very intuitively. DC is used instead of AC because the difficulty of breaking a DC arc is much more difficult than that of an AC arc. In this way, the arc extinguishing capacity under an AC environment can be reflected by a DC current and voltage of a smaller capacity. The present invention cleverly uses the change of the electrical quantity 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 practicability is strong.

[0027] Under the condition that conditions permit, the most direct and effective method is to directly use high-voltage AC power to inject large current into the circuit breaker to test the arc extinguishing ability of the circuit breaker. However, this method requires a very large equipment capacity, because it is the energy required to directly generate a short-circuit fault, which can usually only be completed by the manufacturer. For on-site preventive tests, this solution is obviously unrealistic. However, when the DC current does not cross the zero point, the ability of the circuit breaker with the same mechanical structure to break the DC current is far lower than that of breaking the AC current. For low-voltage switches, the ratio of DC to AC breaking capacity is generally only 1:10, and 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.

[0028] In order to further simulate the short-circuit current breaking characteristics of the real environment, the present invention adopts the mode of joint action of a DC current source and a voltage source. 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 a 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 existence of the current limiting resistor, both power supplies will not 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 large 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 disconnected immediately. If the arc extinguishing ability is insufficient, the large current will be broken down and conducted again by the high voltage between the contacts after being disconnected. However, since the DC current and voltage are both controllable, their overall energy is small and will not damage the arc extinguishing chamber. By simulating the fault current with low-energy DC, the arc extinguishing ability of the circuit breaker can be detected very intuitively.

[0029] 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, so as to further test the arc extinguishing ability 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 opening coil K through the storage oscilloscope 4, the current and voltage changes at the circuit breaker opening moment can be observed very conveniently, and the arc burning time, arc extinguishing speed, and whether there is a current cutoff or restriking problem can be grasped, thereby intuitively detecting the arc extinguishing ability of the circuit breaker.

[0030] Embodiment 2:

[0031] See also Figure 2A vacuum circuit breaker short-circuit current breaking capacity detection device 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 amplitude modulation signal receiver 5. The signal output end of the amplitude modulation signal receiver 5 is connected to the third analog measurement channel of the storage oscilloscope 4, and the connection relationship of the remaining circuit components is the same as that of embodiment 1, which will not be repeated here.

[0032] The high frequency spectrum signal of the arc in the arc extinguishing chamber is received by the AM signal receiver to assist in the analysis and judgment of the arc state, and further accurately determine the arc segmentation capability of the arc extinguishing chamber of the circuit breaker. The circuit principles of other circuit components are the same as those in Example 1, and will not be repeated here.

[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 specification 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 short-circuit current breaking capacity detection device, It is characterized in that It includes 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, and a transient voltage suppression diode D3; 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 arc extinguishing chamber break 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 arc extinguishing chamber break of the vacuum circuit breaker under test; the two ends of the arc extinguishing chamber break of the vacuum circuit breaker under test are connected in parallel with the transient voltage suppression diode D3, and 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 tripping coil K of the vacuum circuit breaker under test; The maximum output voltage of the DC high voltage generator is not less than 5KV; The maximum output current of the DC high current generator is not less than 2KA.

2. The short-circuit current breaking capacity detection device of a vacuum circuit breaker according to claim 1, It is characterized in that It also includes an AM signal receiver, the signal output end of which is connected to the third analog quantity measurement channel of the storage oscilloscope 4 .

3. The short-circuit current breaking capacity detection device of a vacuum circuit breaker according to claim 1 or 2, It is characterized in that The current stabilizing inductor L is an iron core reactor with an air gap.

Images