Universal low voltage bushing terminal quick shorting device for load test of distribution transformer

Abstract

The invention provides a universal low-voltage bushing terminal quick short-circuiting device for load testing of distribution transformers, comprising: a short-circuiting copper bar, a press-fit copper bar, a spring damper and a cam quick disassembly component; the short-circuiting copper bar is provided with a plurality of oblong holes for fixing the press-fit copper bar, and one side of the press-fit copper bar is provided with at least two first circular holes for installing the spring damping device; a second circular hole for installing the cam quick disassembly component is provided at the center position of the other side of the press-fit copper bar, and the central rotating shaft of the cam quick disassembly component is connected to the short-circuiting copper bar through a screw; the invention is suitable for various types of bushing terminals of transformers with a capacity of 30 to 800 kVA, and can ensure that the contact surface is sufficient during the test short-circuiting, the pressure is controllable and adjustable, the device has a simple structure, is easy to process, can realize quick disassembly and assembly, and is convenient for test personnel to carry out load test efficiently and accurately.

Description

Technical Field

[0001] The invention relates to the technical field of load testing of distribution transformers, and in particular to a universal low-voltage bushing terminal quick short-circuiting device for load testing of distribution transformers. Background Art

[0002] The statements in this section merely provide background art related to the present invention and do not necessarily constitute prior art.

[0003] As an important part of the routine tests for transformer products, the load test is required for each 10kV distribution transformer before leaving the factory. The load test is to short-circuit the low-voltage side of the transformer and apply an AC voltage of rated frequency to the high-voltage side so that the current in the coil is the rated value. At this time, the measured loss is the load loss. In the load test, the wire or copper busbar used to connect the short circuit must have a sufficient cross-section and be as short as possible, with good contact at the connection.

[0004] During the load test, the common method of short-circuiting the low-voltage side bushing terminal is to wrap the low-voltage bushing terminal with soft bare copper stranded wire for multiple times, or to use a single copper busbar to punch holes according to the hole spacing and diameter of the bushing terminal, and install it with bolts. Among them, the bare copper wire winding measurement method is efficient, but it is easy to cause insufficient connection surface and large contact resistance, which leads to inaccurate load value measurement and high rework rate; the copper busbar bolt connection method has a tight connection surface and a large contact area, and the measurement result is accurate, but each unit needs to disassemble and assemble fasteners, which is extremely inefficient. It is necessary to install and uninstall the bolts that tighten the copper busbar, and the copper busbar is not universal. It is necessary to prepare copper busbar tooling for various types of transformers, and the copper busbar tooling is expensive. There are other commonly used connection methods, such as using wire clamps to support the bushing terminal, which also has the problem of small connection surface and insufficient support force.

[0005] The inventor found that the capacity of 10kV distribution transformers is mostly 50-800kVA, and the low-voltage bushing spacing is required to be ≥120mm. Usually, the low-voltage bushing spacing of transformers is 120mm for 30-200kVA capacity, 120-140mm for 400kVA capacity, and 160mm for 630-800kVA capacity. According to the different rated voltages of transformers, the bushing terminals selected are also different. Usually, angled terminals and parallel terminals are used. According to the number of terminal openings, there are two types: two holes and four holes. The commonly used two-hole terminal connection surface is about 60-70mm long and 35-40mm wide; the four-hole terminal connection surface is about 50-80mm long and 50-80mm wide, and the openings are mostly φ12 and φ13. For large current terminals, φ15 and other apertures are also used, and the hole spacing is 25mm, 30mm, 40mm, etc. The terminal thickness is 6-12mm. The terminal hole spacing and thickness vary slightly according to different bushing manufacturers and rated currents. Therefore, making corresponding copper busbar tooling for terminal blocks with different spacings and different sizes is not only expensive but also inconvenient to use and store, which seriously affects the test efficiency. Summary of the invention

[0006] In order to overcome the deficiencies in the prior art, the present invention provides a universal low-voltage bushing terminal quick short-circuiting device for load testing of distribution transformers, which is suitable for various types of bushing terminals of transformers with a capacity of 30 to 800 kVA, and can ensure sufficient contact surface during test short-circuiting, and the pressure is controllable and adjustable. The device has a simple structure and is easy to process, and can be quickly disassembled and assembled, making it convenient for test personnel to conduct efficient and accurate load tests.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A first aspect of the present invention provides a universal low-voltage bushing terminal quick short-circuiting device for load testing of a distribution transformer.

[0009] A universal low-voltage bushing terminal quick short-circuit device for load testing of distribution transformers, comprising: a short-circuit copper bar, a press-fit copper bar, a spring damper and a cam quick disassembly component;

[0010] The short-circuit copper bar is provided with a plurality of oblong holes for pressing and fixing the copper bar, and one side of the press-fit copper bar is provided with at least two first circular holes for installing a spring damping device;

[0011] A second circular hole for installing a cam quick disassembly component is provided at the center of the other side of the press-fit copper bar, and the central rotating shaft of the cam quick disassembly component is connected to the short-circuit copper bar through a screw rod.

[0012] Furthermore, the cam quick disassembly component includes at least two cams, which are connected together by a handle.

[0013] Furthermore, one end of the screw is a terminal with a round hole, which passes through the central shaft of the cam quick disassembly component to realize the rotation function, and the other end of the screw passes through the short-circuit copper bar and is installed with a hand-tightening nut.

[0014] Furthermore, the cam handles on both sides of the cam quick disassembly and assembly component press the positions of the copper bar, are respectively provided with square grooves, and are installed with damping rubber pads.

[0015] Furthermore, the spring damping device comprises: a central connecting screw, a hand-tightening nut and two spring units, and the central connecting screw passes through the spring unit and the hand-tightening nut.

[0016] Furthermore, both spring units are compression springs.

[0017] Furthermore, one spring unit is located between the press-fit copper bar and the short-circuit copper bar, and another spring unit is located outside the short-circuit copper bar.

[0018] Furthermore, the short-circuit copper busbar is a red copper busbar with a thickness of 10 mm.

[0019] Furthermore, the pressed copper busbar is a rectangular copper busbar with a thickness of 10 mm.

[0020] A second aspect of the present invention provides a method for quickly short-circuiting a universal low-voltage bushing terminal for a load test of a distribution transformer, using the above-mentioned short-circuiting device, comprising:

[0021] Fine-tune the spring damping component according to the thickness of the transformer low-voltage bushing terminal to be measured to ensure sufficient clamping force during the test;

[0022] Turn the cam quick disassembly handle on the left side of the short-circuit device to the far left to relax the press-fit copper bar. Then place the short-circuit device above the bushing terminal. According to the bushing spacing, slide the press-fit copper bar left and right to adjust the press-fit position. After the adjustment, insert the bushing terminal between the press-fit copper bar and the short-circuit copper bar. Turn the cam quick disassembly handle to the far right to complete the tightening.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The universal low-voltage bushing terminal quick short-circuiting device for load testing of distribution transformers described in the present invention is suitable for various types of bushing terminals of 30-800kVA capacity transformers, and can ensure sufficient contact surface during test short-circuiting, and the pressure is controllable and adjustable. The device has a simple structure and is easy to process. It can be quickly disassembled and assembled, which is convenient for test personnel to conduct efficient and accurate load test.

[0025] 2. The spring damping device described in the present invention comprises two spring units, which can provide sufficient pressure when the copper bar is pressed and tightened. The hand-tightening nut can appropriately adjust the length of the central connecting screw and cooperate with the spring unit to ensure the effective tightening of the sleeve terminal.

[0026] 3. The screw described in the present invention has one end made into a terminal with a round hole, which passes through the central shaft of the cam quick disassembly component to realize the rotation function; the other end passes through the short-circuit copper bar and is installed with a hand-tightening nut, so that the length of the screw shaft can be adjusted to achieve effective clamping of sleeve terminals of different specifications.

[0027] 4. The cam handles on both sides of the cam quick disassembly and assembly component of the present invention press the copper bar, and square grooves are respectively provided and damping rubber pads are installed, so that the disassembly and assembly resistance is small and the wear of the cam and the copper bar is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 It is a partial schematic diagram of the short-circuit structure of the present invention.

[0030] Figure 2 A schematic diagram of a two-hole terminal connection scheme for a low-voltage bushing provided in an embodiment of the present invention.

[0031] Figure 3 A schematic diagram of a four-hole terminal connection scheme for a low-voltage bushing provided in an embodiment of the present invention.

[0032] 1. Short-circuit copper busbar; 2. Press-fit copper busbar; 3. Four-hole terminal; 4. Spring damping device; 5. Two-hole terminal; 6. Cam quick disassembly component. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0034] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0037] Embodiment 1:

[0038] like Figure 1 As shown, embodiment 1 of the present invention provides a universal low-voltage bushing terminal quick short-circuiting device for load testing of distribution transformers. On the basis of considering the width and thickness of the bushing terminal, the influence of the terminal aperture is avoided, a double-sided copper busbar clamping structure is adopted, and a spring damping component and a cam quick-release component are added to control the clamping pressure, so as to realize moderately adjustable clamping force, adjustable clamping position, and quick installation and removal functions.

[0039] Specifically, it includes four parts: a short-circuit copper bar 1, a press-fit copper bar 2, a cam quick disassembly component 6 and a spring damping component 4.

[0040] In this embodiment, the short-circuit copper bar 1 uses a 10 mm thick copper bar as a base material, and is shaped and drilled according to requirements to serve as the main part of the three wiring terminals of the short-circuit low-voltage bushing.

[0041] Specifically, according to different specifications of low-voltage terminal blocks of oil-immersed distribution transformers with a capacity of 50kVA to 800kVA and a voltage level of 10kV, a short-circuit copper bar 1 with a terminal spacing of 120 to 160mm and a width of 30 to 80mm and any length of the terminal is designed; a total of 9 oblong holes are opened on the short-circuit copper bar for adjusting the fixed position of the press-fit copper bar according to the terminal width and spacing.

[0042] In this embodiment, the press-fit copper bar 2 is a rectangular copper bar with a thickness of 10 mm. One end of the press-fit copper bar is connected to the short-circuit copper bar through two spring dampers, and the other end is connected to the short-circuit copper bar through a cam quick-release component.

[0043] Specifically, the press-fit copper bar 2 has 3 pieces in total, and 2 round holes are opened on the right side of the press-fit copper bar 2 for installing the spring damping device, which includes two spring units, and an adjustable central connecting screw passes through the spring unit and a hand-tightening nut. The spring unit can provide sufficient pressure when the press-fit copper bar is tightened, and the hand-tightening nut is used to appropriately adjust the length of the central connecting screw and cooperate with the spring unit to ensure that the sleeve terminal is effectively tightened.

[0044] The two spring units are both pressure springs. One is located between the press-fit copper busbar and the short-circuit copper busbar to play a tightening role, making it convenient to insert the sleeve terminal during the test. The other is located outside the short-circuit copper busbar to provide sufficient pressure when the press-fit spring is installed. The hand-tightening nut can be fine-tuned according to the terminal thickness before the test.

[0045] A circular hole is opened in the center of the left side of the pressed copper bar, and the central rotating shaft of the cam quick disassembly component 6 is connected to the short-circuited copper bar through a screw. The cam quick disassembly component is equipped with two cams, which are connected together by a handle. One end of the screw connecting the pressed copper bar and the cam quick disassembly component on the short-circuited copper bar is made into a terminal with a circular hole, which passes through the central rotating shaft of the cam quick disassembly component to realize the rotation function, and the other end passes through the short-circuited copper bar and is installed with a hand-tightening nut. The length of the screw shaft can be adjusted to achieve effective clamping of sleeve terminals of different specifications. The cam handles on both sides of the cam quick disassembly component press the position of the pressed copper bar, and square grooves are respectively set, and damping rubber pads are installed to ensure that the disassembly resistance is small and avoid wear of the cam and the copper bar.

[0046] Specifically, the connection of the two-hole terminal 5 is as follows Figure 2 As shown, the connection of the four-hole terminal 3 is as follows Figure 3 As shown, the specific method is:

[0047] Fine-tune the spring damping component according to the thickness of the transformer low-voltage bushing terminal to be measured to ensure sufficient clamping force during the test;

[0048] Turn the cam quick disassembly handle on the left side of the short-circuit device to the far left to relax the press-fit copper bar. Then place the short-circuit device above the bushing terminal. According to the bushing spacing, slide the press-fit copper bar left and right to adjust the press-fit position. After the adjustment, insert the bushing terminal between the press-fit copper bar and the short-circuit copper bar. Turn the cam quick disassembly handle to the far right to complete the tightening.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A universal low-voltage bushing terminal quick short-circuit device for load testing of distribution transformers, suitable for various types of bushing terminals of 30-800kVA capacity transformers, characterized by: include: Short-circuit copper bars, press-fit copper bars, spring dampers and cam quick disassembly components; At least two first circular holes for installing a spring damping device are formed on one side of the press-fit copper bar; a second circular hole for installing a cam quick disassembly component is formed at the center of the other side of the press-fit copper bar, and the central rotating shaft of the cam quick disassembly component is connected to the short-circuit copper bar through a screw; the short-circuit copper bar is the main part of the three wiring terminals of the short-circuit low-voltage bushing, and a plurality of oblong holes for fixing the press-fit copper bar are formed on the short-circuit copper bar, so as to adjust the fixing position of the press-fit copper bar according to the width and spacing of the terminals; The cam quick disassembly component includes at least two cams connected together by a handle; One end of the screw is a terminal with a round hole, which passes through the central shaft of the cam quick disassembly component to realize the rotation function, and the other end of the screw passes through the short-circuit copper bar and is installed with a hand-tightening nut; The spring damping device comprises: a central connecting screw, a hand-tightening nut and two spring units, wherein the central connecting screw passes through the spring unit and the hand-tightening nut; The two spring units, one spring unit is located between the press-fit copper bar and the short-circuit copper bar, and the other spring unit is located outside the short-circuit copper bar; When performing quick short-circuiting of low-voltage bushing terminals: Fine-tune the spring damping component according to the thickness of the transformer low-voltage bushing terminal to be measured to ensure sufficient clamping force during the test; Turn the cam quick disassembly handle on the left side of the short-circuit device to the far left to relax the press-fit copper bar. Then place the short-circuit device above the bushing terminal. According to the bushing spacing, slide the press-fit copper bar left and right to adjust the press-fit position. After the adjustment, insert the bushing terminal between the press-fit copper bar and the short-circuit copper bar. Turn the cam quick disassembly handle to the far right to complete the tightening.

2. The universal low-voltage bushing terminal quick short-circuiting device for load testing of distribution transformers according to claim 1, characterized in that: The positions of the cam handles on both sides of the cam quick disassembly and assembly component for pressing and fitting the copper bar are respectively provided with square grooves and are installed with damping rubber pads.

3. The universal low-voltage bushing terminal quick short-circuiting device for load testing of distribution transformers according to claim 1, characterized in that: Both spring units are compression springs.

4. The universal low-voltage bushing terminal quick short-circuiting device for load testing of distribution transformers according to claim 1, characterized in that: The short-circuit copper busbar is a 10mm thick copper busbar.

5. The universal low-voltage bushing terminal quick short-circuiting device for load testing of distribution transformers according to claim 1, characterized in that: The pressed copper busbar is a rectangular copper busbar with a thickness of 10mm.

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