TWI416129B - Quality testing method for transformer bushings - Google Patents

Abstract

A quality testing method for transformer bushings mainly includes a step of using a frequency response analyzer to measure and obtain an I-F response curve for a standard bushing, a step of using the frequency response analyzer to measure and obtain an I-F response curve for a to-be-tested bushing, and a step of comparing the impedance differential of the two I-F response curves only within 600 kHz, wherein when the impedance differential is beyond a threshold, the to-be-tested bushing is determined to be failed. Therefore, the method of the invention features a fast, safe and accurate testing procedure.

Description

Test method for transformer insulation bushing

The invention relates to an inspection method, in particular to an inspection method suitable for a transformer insulating sleeve.

Power equipment is an important unit for maintaining the electricity used by the people on the birthday of the people and the demand for electricity for industrial production. Generally, it is often found in large power transformers or factories in substations, and small power transformers are responsible for normal power transmission. However, due to the different application range of the transformer, the transformer must be subjected to voltage switching to meet the requirements of various working voltages. Therefore, the transformer is internally provided with a plurality of ceramic sleeves made of ceramic materials, and terminals are further assembled thereon. In order to form the transformer casing, the basic function of the transformer is achieved.

The transformer needs to be tested before leaving the factory. After the test meets the standard requirements, it needs to be dismantled and transported to the place for reinstallation. Therefore, the transformer casing needs to be assembled and disassembled several times from manufacturing to completion and delivery to the customer. .

When the casing is assembled or disassembled, the porcelain sleeve of the casing is a ceramic product. When assembling or disassembling the terminal thereon, if the construction worker is slightly negligent, the hand tool for assembling the terminal such as a wrench or a lock is used. Foreign objects such as screws of the solid terminal may collide with the porcelain sleeve, causing damage to the porcelain sleeve. The casing is also damaged during handling.

Because transformer bushings can be damaged in many ways: impact damage, dirt, moisture and moisture, etc., must be carefully tested for safe use. The conventional inspection casing uses a power factor tester to apply a voltage of 10 kV to the casing to be tested and directly obtain an insulation power factor. The disadvantage is that the use of high voltage is dangerous, time consuming, particularly susceptible to the effects of rain and humidity, and the preparation time of related equipment is too long.

Therefore, it is necessary to develop a new casing inspection method to obtain a more accurate judgment on whether the casing is qualified or not. The reason for the inventor is that, in the spirit of active invention and creation, a method for detecting the above problems can be considered, and the present invention is completed after several research experiments.

The main object of the present invention is to provide a test method for a transformer insulating sleeve, which can quickly and safely inspect the quality of an insulating sleeve.

In order to achieve the above object, the inspection method of the transformer insulating sleeve of the present invention detects the quality of an insulating sleeve to be tested by using a commercially available frequency response analyzer (FRA). The frequency response analyzer includes a receiver and a transmitter, and both the receiver and the transmitter include a power terminal and a ground terminal.

The test method for the transformer insulating sleeve includes: Step A: respectively connecting a porcelain sleeve portion of a standard insulating sleeve and a grounding point with a grounding conductor, and the grounding terminal of the receiver and the grounding terminal of the transmitter Connecting the porcelain sleeve portion of the standard insulating sleeve; step B: connecting the energizing terminal of the receptacle and the energizing terminal of the emitter to each end of one of the standard insulating sleeves; step C: The frequency response analyzer is activated to obtain a standard impedance-frequency response curve. Step D: respectively connecting a porcelain sleeve portion of the insulating sleeve to be tested and the grounding point with a grounding conductor, and grounding the receiver The terminal and the grounding terminal of the transmitter are connected to the porcelain sleeve of the insulating sleeve to be tested; Step E: connecting the energizing terminal of the receiver and the energizing terminal of the transmitter to the insulating sleeve to be tested One end of the conductor portion of the tube; step F: starting the frequency response analyzer to obtain an impedance-frequency response curve of the device to be tested; and step G: comparing the impedance-frequency response curve of the standard member with the impedance of the device to be tested - To 600kHz frequency response curve within a frequency difference between any point of the impedance, when the impedance of any frequency point difference exceeds a threshold value, i.e. it determines that the failure test bushing.

With the inspection method of the present invention, it is only necessary to use a small volume of FRA for detection. Compared with the conventional use of a power factor measuring instrument, it is necessary to cooperate with many circuit devices. The present invention eliminates the need for a large space, and of course, the system is also erected. A lot faster. Moreover, the FRA of the present invention requires only low voltage operation, has advantages in terms of safety as compared with the prior art, has a lower risk of damage to the object, and the overall inspection process is also faster than the conventional one.

The insulating sleeve to be inspected may be an oil-immersed insulating sleeve, but it is of course not limited thereto, and other resin-like insulating sleeves are also applicable. Where the oil-immersed insulating sleeve is grounded, the porcelain sleeve portion of the insulating sleeve includes a grounding flange, and the grounding terminal of the receiver and the grounding terminal of the transmitter are connected to the grounding flange.

In the inspection method, the threshold value is set according to the different requirements of the casing, and there is no uniform value, for example, it can be set to 1 ohm in some cases.

The invention mainly uses a frequency response analyzer which is known for measuring transformer winding deformation to detect the quality of a transformer insulating sleeve, that is, to make a qualified judgment. This instrument is a commercial product based on frequency response analysis and is currently available on the market.

Refer to Figure 1~2 for the schematic diagram and inspection flow chart of the transformer insulation casing inspection equipment. A preferred embodiment of the process for verifying the transformer bushing will be described below. First, an impedance-frequency response curve is required as a reference standard, that is, a reference material for establishing the same type and type of insulating sleeve (hereinafter referred to as a standard insulating sleeve) having a standard usable quality. In the method of step 101, a frequency response analyzer 10 and a standard sleeve 20 are prepared. The frequency response analyzer has a receiver 21 and a transmitter 22, and both the receiver 21 and the transmitter 22 are provided with a fixture type. One of the states is a power terminal 211, 221 and a ground terminal 212, 222.

In the present embodiment, the insulating sleeve as the object to be inspected is an oil-immersed insulating sleeve for use in an oil-immersed transformer. However, the scope of application of the present invention is of course not limited thereto, and a resin-type insulating sleeve is also applicable. The oil-immersed insulating sleeve 20 mainly includes a columnar conductor portion 201 and a porcelain sleeve portion 202 sleeved on the outside of the conductor portion 201, and the porcelain sleeve portion 202 further includes a grounding flange 203 protruding outward.

Next, in step 102, a porcelain sleeve portion 202 of a standard insulating sleeve 20 and a grounding point 12 (such as a ground net) are respectively connected by a grounding conductor 11. Further, the ground terminal 212 of the receptacle 21 and the ground terminal 222 of the transmitter 22 are connected (clamped) to the ground flange 203 of the porcelain sleeve portion 202. At this point, the grounding action on the insulating sleeve 20 is completed. Of course, the length of the grounding wire 11 will affect the measurement results, and the shorter the result, the better.

In step 103, the energizing terminal 211 of the receptacle 21 and the energizing terminal 221 of the transmitter 22 are respectively connected to both ends of the conductor portion 201 of the standard insulating sleeve 20. In step 104, the frequency response analyzer 10 is activated, thereby directly displaying the impedance-frequency response curve (referred to as the standard impedance-frequency response curve) of the corresponding standard insulating sleeve on the screen 13 of the analyzer, as shown in FIG. Curve A, the horizontal axis of the graph is the frequency (unit: Hertz; Hz), and the vertical axis is the impedance (unit: ohm; ohm). .

After obtaining the standard curve data, the same measurement can be performed for the same type of insulating sleeve 30 to be tested. In step 105, the grounding lead 11 is connected to the grounding flange 303 of the porcelain sleeve 302 of the insulating sleeve 30 to be tested and the grounding point 12, and the grounding terminal 212 of the receptacle 21 is connected to the grounding terminal 222 of the transmitter 22. The porcelain sleeve portion 302 of the insulating sleeve 30 to be tested completes the grounding step.

In step 106, the energizing terminal 211 of the receptacle 21 and the energizing terminal 221 of the transmitter 22 are respectively connected to the two ends of the conductor portion 301 of the insulating sleeve 30 to be tested. In step 107, the frequency response analyzer 10 is activated to obtain a impedance-frequency response curve of the device to be tested, as shown by curve B in FIG.

Finally, the impedance-frequency response curve of the standard component obtained above is compared with the impedance-frequency response curve of the device to be tested. In particular, it is only necessary to check the difference between the longitudinal axis (impedance) of the two response curves within the frequency band of 600 kHZ to accurately determine the quality of the insulating sleeve. When the impedance difference of any frequency point exceeds a threshold value, it is determined that the casing to be tested is unqualified. In this embodiment, the threshold value is 1 ohm.

The setting of the threshold value depends mainly on the application of the insulating sleeve, and the value can of course be lowered in the pursuit of higher quality.

The impedance difference determination can be visually judged (with the vertical axis scale) by directly observing the difference curve of the two response curves displayed on the screen (curve C of FIG. 3).

In addition to visually observing the difference curve, it is also possible to determine whether the impedance difference exceeds the threshold value by the built-in program calculation function of the instrument itself, and easily display the impedance difference of any corresponding frequency point on the two response curves by digital display. On the instrument screen 13. Referring to FIG. 4, in another embodiment, after obtaining two sets of response curves, the specified calculation cursor is moved to a frequency point of 600 kHz, and the two response curves D and E are obtained by an instrument calculation, and the frequency is more than 1 ohm at a frequency of 600 kHz. The difference is judged as unsatisfactory.

It can be seen from the above that the invention is characterized in that the FRA instrument originally used for measuring the transformer core and the winding displacement deformation is used for measuring the transformer insulating sleeve, thereby judging whether the casing is damaged, dirty or damp. Loss of workability in a specific situation (judgment failure) can be performed by applying only a low voltage of 8 V, and it is operationally safe. In addition, because the FRA instrument is portable, the equipment for detecting the operation is very simple and fast, and does not require much space as a whole.

The above-mentioned embodiments are merely examples for convenience of description, and the scope of the claims is intended to be limited to the above embodiments.

10. . . Frequency response analyzer

11. . . Ground wire

12. . . Grounding point

13. . . Screen

20. . . Standard casing

201,301. . . Conductor

202,302. . . Porcelain sleeve

203,303. . . Ground flange

twenty one. . . Receiver

211,221. . . Power terminal

212,222. . . Ground terminal

twenty two. . . launcher

30. . . Insulation sleeve to be tested

101~108. . . step

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view of a related device for testing an insulating bushing of a transformer according to a preferred embodiment of the present invention.

2 is a flow chart showing the inspection of a transformer insulating sleeve according to a preferred embodiment of the present invention.

Figure 3 is an impedance-frequency response curve and a difference curve of the test results of the transformer bushing of the present invention.

Figure 4 is a digital display of the impedance-frequency response curve and the difference calculation of the test results of the transformer bushing of the present invention.

101~108. . . step

Claims (5)

A method for inspecting a transformer insulating sleeve, which uses a frequency response analyzer to detect the quality of an insulating sleeve to be tested, the frequency response analyzer comprising a receiver and a transmitter, the receiver and the transmitter each including a The power terminal and the ground terminal, the method includes: Step A: connecting a porcelain sleeve portion of a standard insulating sleeve and a grounding point with a grounding wire, and the grounding terminal of the receiver and the emitter The grounding terminal is connected to the porcelain sleeve portion of the standard insulating sleeve; step B: connecting the energizing terminal of the receptacle and the energizing terminal of the emitter to each end of the conductor portion of the standard insulating sleeve; C: starting the frequency response analyzer to obtain a standard impedance-frequency response curve; step D: respectively connecting a porcelain sleeve portion of the insulating sleeve to be tested and the grounding point with a grounding wire, and the receiving device The grounding terminal and the grounding terminal of the transmitter are connected to the porcelain sleeve portion of the insulating sleeve to be tested; Step E: respectively, the energizing terminal of the receiver and the energizing terminal of the transmitter respectively Connected to one end of the conductor portion of the insulating sleeve to be tested; step F: start the frequency response analyzer to obtain a impedance-frequency response curve of the device to be tested; and step G: compare the impedance-frequency response curve of the standard component with The impedance-frequency response curve of the device to be tested has an impedance difference at any frequency point within 600 kHz. When the impedance difference of the frequency point exceeds a threshold value, the insulation sleeve to be tested is determined to be unqualified. The method of claim 1, wherein the insulating sleeve to be tested is an oil-immersed insulating sleeve. The method of claim 2, wherein the porcelain sleeve portion of the insulating sleeve to be tested comprises a grounding flange, and the grounding terminal of the receiver is connected to the grounding terminal of the emitter Ground flange. The method of claim 1, wherein the threshold value is 1 ohm. The method of claim 1, wherein the standard insulating sleeve and the insulating sleeve to be tested are of the same type and the same type.