Test device for testing the mechanical properties of parts of power transformers

Abstract

The present invention relates to the field of power transformers, and provides a testing device for testing the mechanical properties of parts of power transformers, the testing device comprising a C-shaped core, an excitation coil wound on the C-shaped core, a shielding cover surrounding the two ends of the C-shaped core, a clamping device for clamping the parts, and a power supply for supplying power to the excitation coil and the parts. When the excitation coil is energized, a magnetic field is generated between the two ends of the C-shaped core, and a hole is provided on the shielding cover that passes through the shielding cover perpendicular to the direction of the magnetic field, so that the parts can pass through the magnetic field perpendicular to the direction of the magnetic field through the hole. When current flows through the parts, the flowing charges will be affected by the Lorentz force in the magnetic field, thereby simulating the so-called short-circuit force generated when the power transformer is short-circuited. The device of the present invention can simulate various short-circuit situations of the power transformer, with low verification cost and short cycle, and low requirements on test site conditions.

Description

Technical Field

[0001] The invention relates to the field of power transformers, and in particular to a testing device for testing the mechanical properties of parts of a power transformer. Background Art

[0002] Power transformers are indispensable voltage regulating equipment in power systems. They can not only increase voltage to deliver electricity to power consumption areas, but also reduce voltage to various levels of voltage to meet the voltage requirements of different users. The short-circuit resistance of transformers is an important indicator of transformers. When a transformer is short-circuited, the maximum short-circuit current can reach dozens of times the rated current. Since the so-called short-circuit force (i.e. the macroscopic manifestation of the Lorentz force, Ampere force) generated during a short circuit is proportional to the square of the current, the short-circuit force on the windings, wires and other energized parts in the power transformer when a short circuit occurs will be hundreds of times that of normal operation, which will cause damage to the transformer. Therefore, how to verify the short-circuit resistance of each component in the transformer is an important topic in this field.

[0003] At present, the transformer's short-circuit resistance is generally verified through whole-machine test verification and calculation verification. For whole-machine test verification, the verification cost is high, the cycle is long, and there are few test sites that can meet the transformer whole-machine verification conditions, because it is difficult and expensive to generate the magnetic field strength during short circuit by providing a current dozens of times the rated current. If the test is unsuccessful, a lot of time and money costs will be lost. For calculation verification, the models and methods currently used are different, the calculated results are less reliable, and the calculation verification is usually based on steady-state force calculation considerations, which is also different from the transient short-circuit force generated when the transformer is short-circuited. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides a testing device for testing the mechanical properties of parts of a power transformer. The testing device utilizes a C-shaped core to generate a strong magnetic field, and simulates various short-circuit conditions of the power transformer through controllable sample current and excitation current. The short-circuit resistance capability of the components of the power transformer can be verified without the need for a large current and a complete power transformer model. The verification cost is low, the cycle is short, and the requirements for test site conditions are low.

[0005] The present invention provides a testing device for testing the mechanical performance of a part in a power transformer through which current flows when the coil of the power transformer is short-circuited. The testing device comprises:

[0006] a C-shaped core having a first end and a second end extending toward each other;

[0007] One or more excitation coils, the one or more excitation coils are wound around the C-shaped core, and when the excitation coils are energized, a magnetic field along a first direction is generated between the first end and the second end;

[0008] a shielding cover formed of a diamagnetic material, the shielding cover surrounding the first end and the second end to shield the magnetic field in a first direction generated between the first end and the second end from the outside, the shielding cover comprising a hole allowing the part to pass through the shielding cover in a second direction perpendicular to the first direction so as to extend in the magnetic field generated between the first end and the second end in the second direction;

[0009] A clamping device, wherein the clamping device clamps a portion of the part exposed outside the shielding cover when the part passes through the hole of the shielding cover;

[0010] A power source is used to supply power to the excitation coil and the part to generate a magnetic field between the first end and the second end and to make a current flow through the part, so that the charge flowing through the part is affected by the Lorentz force in the magnetic field.

[0011] According to a preferred embodiment of the present invention, the magnetic field strength of the magnetic field between the first end and the second end is greater than the magnetic field strength of the magnetic field generated when the coil of the power transformer is short-circuited, and the current strength of the current flowing through the part is less than the current strength of the short-circuit current when the coil of the power transformer is short-circuited.

[0012] According to a preferred embodiment of the present invention, the excitation coil includes a first excitation coil and a second excitation coil, the first excitation coil is arranged at the first end, and the second excitation coil is arranged at the second end.

[0013] According to a preferred embodiment of the present invention, the power supply includes a first power supply and a second power supply, the first power supply is used to supply power to the excitation coil, and the second power supply is used to supply power to the part.

[0014] According to a preferred embodiment of the present invention, the power supply provides alternating current with a frequency of 50 Hz or 60 Hz.

[0015] According to a preferred embodiment of the present invention, the hole allows a wire used as a part of a power transformer to pass through the shield in a second direction perpendicular to the first direction so as to extend in the magnetic field generated between the first end and the second end in the second direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following drawings are intended only to illustrate and explain the present invention, and do not limit the scope of the present invention.

[0017] Figure 1 is a schematic side view of a device according to a preferred embodiment of the present invention, wherein the clamping device and parts are not shown.

[0018] Figure 2 yes Figure 1 Schematic side view of the C-shaped core in the device shown.

[0019] Figure 3 Schematically shows Figure 1 The device is shown in a front cross-sectional view taken at the hole through which the parts pass, showing for clarity only the shielding cover formed of diamagnetic material of the device of the present invention.

[0020] Figure numerals: 100—test device for testing the mechanical properties of a part in a power transformer through which current flows when the coil of the power transformer is short-circuited; 10—C-shaped core; 11—first end; 12—second end; 13—disconnection gap; 20—first excitation coil; 30—second excitation coil; 40—shielding cover; 41—hole; 50—part; 60—power supply; A—magnetic field direction; B—current direction; C—electromagnetic force (short-circuit force) direction DETAILED DESCRIPTION

[0021] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described with reference to the accompanying drawings. In the drawings, the same reference numerals represent components with the same structure or similar structures but the same functions.

[0022] In this document, “exemplary” means “serving as an example, instance or illustration”, and any diagram or implementation described in this document as “exemplary” should not be interpreted as a more preferred or more advantageous technical solution.

[0023] In order to simplify the drawings, only the parts related to the present invention are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked.

[0024] Figure 1 A schematic side view of a testing device 100 for testing the mechanical performance of a part in which current flows in a power transformer when the coil of the power transformer is short-circuited according to a preferred embodiment of the present invention is schematically shown. As shown in the figure, the testing device comprises: a C-shaped core 10 for providing a path for a magnetic field, the C-shaped core having a first end 11 and a second end 12 extending toward each other, and a disconnection gap 13 is formed between the first end 11 and the second end 12 (see Figure 2); one or more excitation coils for energizing and generating a magnetic field, although Figure 1 Two excitation coils 20 and 30 are shown in the figure, but those skilled in the art can realize that there can be one or more excitation coils, and the excitation coils are wound on the C-shaped core 10. When the excitation coils are energized, a magnetic field from the first end 11 to the second end 12 or a magnetic field from the second end 12 to the first end 11 is generated at the disconnection gap 13 between the first end 11 and the second end 12; a shielding cover 40 formed of a diamagnetic material and arranged around the first end 11 and the second end 12 to prevent excessive divergence of the magnetic field at the disconnection gap 13, the shielding cover 40 is provided with a hole 41 penetrating the shielding cover in a direction perpendicular to the magnetic field at the disconnection gap, as shown in FIG. Figure 3 As shown, the hole 41 is used for the part 50 to pass therethrough so that the part 50 passes through the magnetic field transversely to the direction of the magnetic field at the disconnected notch; a clamping device (not shown in the figure), which can clamp the part 50 exposed outside the shielding cover 40 when the part 50 passes through the hole 41 of the shielding cover 40; a power supply 60, which is used to provide the same or different currents to the excitation coil and the part 50, and the power supply frequency can be 50 Hz or 60 Hz. The power supply 60 can generate a current of a predetermined amplitude, phase angle and duration according to the test requirements.

[0025] In a preferred embodiment of the present invention, the first excitation coil 20 is disposed near the first end 11 of the C-shaped core 10 , and the second excitation coil 30 is disposed near the second end 12 of the C-shaped core 10 .

[0026] In a preferred embodiment of the present invention, two power supplies can be used to provide currents with the same or different predetermined amplitudes, phase angles and durations to the excitation coil and the component, respectively.

[0027] When using the above device to apply electromagnetic force to the part to simulate the short-circuit force generated when the power transformer is short-circuited, pass the part 50 (such as a wire) through the hole 41 on the shielding cover 40; clamp the part 50 exposed outside the shielding cover 40 by a clamping device; connect the excitation coil and the part to the power supply 60. It can be seen from the above content that in a preferred embodiment of the present invention, the excitation coil and the part can be connected to different power supplies respectively to provide the excitation coil and the part with the same or different currents of predetermined amplitude, phase angle and time duration according to test requirements; the excitation coil and the part are powered by the power supply, and the C-shaped core 10 can generate a strong magnetic field under the action of the excitation coil, so that the short-circuit force generated when the transformer is short-circuited can be simulated without passing excessive current through the part. Figure 3As schematically shown, at this time, the direction of the magnetic field A is perpendicular to the paper surface and shoots toward the paper surface, and the direction B of the current flowing through the part 50 is from left to right. According to the left-hand rule for determining the direction of the Lorentz force, at this time, the part 50 will be subjected to the Ampere force upward along the direction C (the macroscopic manifestation of the Lorentz force). By adjusting the current intensity provided to the excitation coil and the part, the Ampere force can be used to simulate the so-called short-circuit force that the part will be subjected to when the transformer is short-circuited, thereby verifying whether the mechanical properties of the part, such as strength and deformation resistance, meet the short-circuit resistance.

[0028] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0029] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes, modifications and combinations made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A testing device (100) for testing the mechanical properties of parts of a power transformer, characterized in that: The testing device (100) comprises: A C-shaped core (10), the C-shaped core having a first end (11) and a second end (12) extending toward each other, and a disconnection notch (13) formed between the first end (11) and the second end (12); One or more excitation coils (20; 30), the one or more excitation coils being wound on the C-shaped core (10), and when the excitation coils are energized, a magnetic field along a first direction is generated at the disconnection gap (13) between the first end (11) and the second end (12), wherein the first direction is a direction from the first end (11) to the second end (12) or a direction from the second end (12) to the first end (11); a shielding cover (40) formed of a diamagnetic material, the shielding cover surrounding the first end (11) and the second end (12) to shield the magnetic field generated between the first end (11) and the second end (12) in the first direction from the outside, the shielding cover comprising a hole (41) allowing the part (50) to pass through the shielding cover in a second direction perpendicular to the first direction so as to extend in the magnetic field generated between the first end (11) and the second end (12) in the second direction; a clamping device, wherein the clamping device clamps a portion of the part (50) exposed outside the shielding cover (40) when the part (50) passes through the hole (41) of the shielding cover; a power source (60) for supplying power to the excitation coil (20; 30) and the part (50) to generate a magnetic field between the first end (11) and the second end (12) and to cause a current to flow through the part (50), thereby applying to the part (50) a force equivalent to the force to which the part (50) is subjected when the coil of the transformer is short-circuited when the part is installed in the power transformer; The magnetic field strength of the magnetic field between the first end (11) and the second end (12) is greater than the magnetic field strength of the magnetic field generated when the coil of the power transformer is short-circuited, and the current strength of the current flowing through the component (50) is less than the current strength of the short-circuit current when the coil of the power transformer is short-circuited.

2. The testing device according to claim 1, characterized in that: The excitation coil (20; 30) comprises a first excitation coil (20) and a second excitation coil (30), wherein the first excitation coil is arranged at the first end (11) and the second excitation coil is arranged at the second end (12).

3. The testing device according to claim 1, characterized in that: The power source (60) comprises a first power source and a second power source, wherein the first power source is used to supply power to the excitation coil (20; 30), and the second power source is used to supply power to the part (50).

4. The testing device according to claim 1, characterized in that: The power source (60) provides alternating current with a frequency of 50 Hz or 60 Hz.

5. The testing device according to claim 1, characterized in that: The hole (41) allows a wire used as a part of an electric transformer to pass through the shield (40) in the second direction perpendicular to the first direction so as to extend in the second direction in the magnetic field generated between the first end (11) and the second end (12).

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