A portable live test device for zero-sequence current transformer

Abstract

In order to solve the potential safety hazard problem in the process of transformer testing, the present invention provides a portable zero-sequence current transformer live testing device, comprising an insulating shell, a fixed rod, a handle fixedly connected to the rear end of the fixed rod, a moving rod, a shaped frame, a signal display circuit and a polarity testing circuit arranged between the shaped frame and the fixed rod, the signal display circuit is composed of a first metal sheet, a first power supply, an indicator light and a second metal sheet connected in series in sequence through a first wire, the polarity detection circuit is composed of a third metal sheet, a travel switch, a second power supply and a fourth metal sheet connected in series in sequence through a second wire, the travel switch is fixedly connected to the front inner part of the fixed rod, when the fixed rod slides forward and the front end is in contact with the shaped frame, the first metal sheet is connected to the second metal sheet, the third metal sheet is connected to the fourth metal sheet, the travel switch is normally open, and when the moving rod moves forward, the front end of the moving rod touches the travel switch button, and the travel switch is closed.

Description

Technical Field

[0001] The invention relates to the technical field of current transformers, and in particular to a portable live testing device for a zero-sequence current transformer. Background Art

[0002] At present, most medium-voltage distribution networks adopt the operation mode of ungrounded neutral point or grounded through arc suppression coil. The outgoing cable of 10kV bus is equipped with zero-sequence current transformer. When a ground fault occurs, zero-sequence current will appear in the 10kV distribution system. The function of zero-sequence current transformer is to sense zero-sequence current, so that the grounding line selection device can accurately detect and identify the faulty line.

[0003] During the installation of the zero-sequence current transformer, the polarity installation error may occur, resulting in the wrong direction of the zero-sequence current collected by the grounding line selection device, and the inability to accurately select the grounding fault line. When the power system is operating normally, due to the three-phase balance, there is almost no zero-sequence current in the system, and the zero-sequence current sensed by the zero-sequence current transformer is almost zero. Therefore, it is impossible to detect whether the polarity of the zero-sequence current transformer is correct when the line is operating normally.

[0004] At present, the method for testing the polarity of zero-sequence current transformers is a power-off test. Due to the requirement of power supply reliability of the power system, it is obviously unrealistic to test the polarity of zero-sequence current transformers by powering off the operating lines. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a portable zero-sequence current transformer live testing device, and the technical solution adopted is as follows:

[0006] A portable live testing device for zero-sequence current transformer, characterized in that it mainly comprises an insulating shell, a fixed rod slidably connected to the inside of the insulating shell along the length direction of the insulating shell, a handle fixedly connected to the rear end of the fixed rod, a moving rod coaxially distributed with the fixed rod and sliding along the length direction of the fixed rod, a shaped frame fixedly connected to the front of the insulating shell, a signal display circuit and a polarity test circuit arranged between the shaped frame and the fixed rod, The signal display circuit is composed of a first metal sheet, a first power supply, an indicator light and a second metal sheet connected in series in sequence through a first wire, the first metal sheet is fixedly connected to the front end face of the fixed rod, the second metal sheet is fixedly connected to the shaped frame and its position is distributed correspondingly to the first metal sheet, one end of the first wire is fixedly connected to the first metal sheet, and after being connected to the first power supply and the indicator light in sequence, the other end is fixedly connected to the second metal sheet; the polarity detection circuit is composed of a third metal sheet, a travel switch, a second power supply and a fourth metal sheet connected in series in sequence through a second wire, the travel switch is fixedly connected to the front inner part of the fixed rod, the third metal sheet is fixedly connected to the front end face of the fixed rod, and the fourth metal sheet is fixedly connected to the shaped frame and its position is distributed correspondingly to the third metal sheet; when the fixed rod slides forward and the front end is in contact with the shaped frame, the first metal sheet is connected to the second metal sheet, the third metal sheet is connected to the fourth metal sheet, the travel switch is normally open, and when the moving rod moves forward, the front end of the moving rod touches the travel switch button, and the travel switch is closed.

[0007] Preferably, the first conducting wire is distributed along the inside of the fixing rod and the inside of the shaped frame, and the first power supply and the indicator light are both fixedly connected to the shaped frame.

[0008] Preferably, the second conducting wire is distributed inside the fixing rod and the profile frame, and the second power supply is fixedly connected to the insulating housing.

[0009] Preferably, the rear end of the insulating shell is further provided with a sliding seat located below the handle, the sliding seat is fixedly connected to the rear end below the insulating shell, and a sliding groove is provided inside, and the lower end of the handle is connected to the sliding groove for forward and backward sliding.

[0010] Preferably, a first spring with its axis distributed along the front-to-back direction is provided between the front end of the handle and the sliding seat.

[0011] Preferably, a limit block with adjustable height is provided at the rear end of the sliding groove on the sliding seat.

[0012] Preferably, the front end of the limit block is connected to the upper surface of the sliding groove by a compression spring, the rear end of the limit block is hinged to the upper surface of the sliding groove, and in a normal state, the upper end of the limit block is located above the lower end surface of the handle.

[0013] Preferably, a push rod is connected to the rear end of the moving rod for pushing the moving rod to slide forward.

[0014] Preferably, the handle is in a rectangular frame structure. The rear end of the moving rod passes through the front end of the handle and is located inside the handle and hinged to the push rod. The push rod is composed of a first rod body and a second rod body fixedly connected to the rear of the first rod body. The first rod body is distributed obliquely downward from back to front. The front end of the first rod body is hinged to the handle and can rotate obliquely upward along the inner wall of the handle. The second rod body is distributed obliquely upward from back to front. The second rod body and the first rod body are distributed at a certain angle, and the moving rod is hinged to the connection point between the first rod body and the second rod body.

[0015] Preferably, a return spring is arranged between the first rod body and the handle.

[0016] The beneficial effects of the present invention are as follows: The device integrates a signal indication circuit and a polarity detection circuit, can realize the polarity test of the zero-sequence current transformer under live conditions, ensure that the tester and the live equipment maintain a sufficient safety distance, and there is no need to cut off the power of the line, so it has the effects of safety and reliability, convenience and speed, time saving and labor saving. Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of the present invention

[0018] Figure 2 is Figure 1 a partial structural diagram of the front half

[0019] Figure 3 is Figure 1 a partial structural diagram of the rear half (the return spring is not shown)

[0020] Figure 4 is a schematic connection structure diagram of the limit block and the sliding seat

[0021] Figure 5 is a schematic detection state diagram

[0022] Figure 6 is a schematic signal display circuit diagram

[0023] Figure 7 is a schematic polarity detection circuit diagram

[0024] Among them, 1-insulating housing, 2-handle, 3-fixed rod, 4-moving rod, 5-push rod, 501-first rod body, 502-second rod body, 503-return spring, 6-limit block, 7-sliding seat, 8-sliding groove, 9-compression spring, 10-first spring, 11-travel switch, 12-first battery, 13-second battery, 14-indicator light, 15-first metal connecting piece, 16-second metal connecting piece, 17-third metal connecting piece, 18-fourth metal connecting piece, 19-冂-shaped frame, 20-first wire, 21-second wire, R-resistor. Detailed Embodiments

[0025] The following will refer to the attached Figure 1-7 Exemplary embodiments of the present disclosure are described in more detail. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0026] In the description of the invention, it is necessary to understand that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are orientations or positional relationships based on actual use, and are only for the convenience of describing the invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention.

[0027] like Figure 1-7The portable zero-sequence current transformer live test device shown mainly includes an insulating shell 1, a fixed rod 3, a movable rod 3, a handle 2, a sliding seat 7, a limit block 6, a shaped frame 19, a signal display circuit, and a polarity detection circuit. The insulating shell 1 is a cylindrical shell with a hollow interior and no covers at both ends. In actual use, the axis of the insulating shell 1 is distributed along the front and rear directions. The fixing rod 3 is a cylindrical shell with a hollow interior and no cover at the rear end. The fixing rod 3 is coaxially connected to the inside of the insulating shell 1 for forward and backward sliding. The rear end of the fixing rod 3 is fixedly connected to the handle 2. The handle 2 is a rectangular frame structure with a length distributed along the front-to-back direction. The rear end of the fixing rod 3 is fixedly connected to the upper front end of the handle 2. The rear end of the insulating shell 1 is also fixedly connected to a sliding seat 7. The sliding seat 7 is located below the handle 2. A sliding groove 8 distributed in the front-to-back direction is provided on the bottom plate of the sliding seat 7. The handle 2 cooperates with the sliding groove 8, and the handle 2 can slide along the front-to-back direction of the sliding groove 8. A first spring 10 is connected between the front end of the handle 2 and the inner wall of the front end of the sliding seat 7. The axis of the first spring 10 is distributed along the front-to-back direction, and is mainly used to prevent the handle 2 from being pulled out of the sliding groove 8. In addition, a sliding groove 8 is also provided at the rear end A limit block 6 is provided, the rear end of the limit block 6 is hinged to the sliding seat, and the front end is fixedly connected to the sliding groove 8 through a compression spring 9 distributed in the vertical direction of the axis. When not affected by external force, the compression spring 8 lifts the limit block 6 to a certain height, and the height of the front end of the upper end face of the limit block 6 is higher than the height of the lower end face of the handle 2. When the limit plate 6 is subjected to a vertical downward force, the upper end face of the limit block 6 can be flush with the upper end face of the sliding groove 6, which is convenient for the handle 2 to slide out backward. The main purpose of setting the compression spring 8 is that after the handle 2 is pushed forward, it will not slide backward, ensuring that the position of the front end of the fixed rod 3 remains unchanged. The handle 2 can drive the fixed rod 3 to slide back and forth inside the insulating shell 1, and the sliding groove 8 guides the sliding direction. The limit block 6 and the first spring 10 are used to limit the position of the handle 2.

[0028] The moving rod 3 is coaxially distributed inside the fixed rod 3, and the rear end of the moving rod 3 passes through the front end of the handle 2 and is connected to the push rod 5. The push rod 5 has a structure as shown in FIG. Figure 1 and Figure 3As shown, the push rod 5 consists of a first rod body 501 and a second rod body 502 fixedly connected to the rear of the first rod body 501. The axis of the first rod body 501 is tilted downward from the back to the front, that is, the front end is located below the rear end, and the front end of the first rod body 501 is hinged to the front end of the inner wall of the handle 2. The first rod body 501 can rotate forward along the handle 2, and the axis of the second rod body 502 is tilted upward at a certain angle from the back to the front, that is, the front end is located above the rear end, a return spring 503 is fixedly connected between the second rod body 502 and the upper end of the inner wall of the handle 2, and the rear end of the moving rod 3 is hinged to the connection point between the first rod body 501 and the second rod body 502. By pushing the second rod body 502 upward, the first rod body 501 can be driven to rotate forward, and the moving rod 3 can be moved forward at the same time. After releasing the second rod body 502, the push rod 5 and the moving rod 3 are reset under the action of the return spring 503.

[0029] A shaped frame 19 is fixedly connected to the upper front end of the insulating shell 1. The shaped frame 19 is a rectangular frame structure with an open lower end, and the length direction is distributed along the axial direction of the insulating shell shaft 1. The right end of the fixing rod 3 is fixedly connected to the first metal sheet 15 and the second metal sheet 17 distributed up and down. The lower end of the right inner wall of the shaped frame 19 is fixedly connected to a groove that is matched and connected to the right end of the fixing rod 3. The second metal sheet 16 and the fourth metal sheet 18 distributed in the up and down directions are arranged in the groove. One end of the first wire 20 is connected to the first metal sheet 15. The first wire 20 is distributed to the left inside the fixing rod 3 and then passes upward through the insulating shell 1 and enters the shaped frame 19. It is connected in series with the indicator light 14 and the first power supply 12 in sequence, and then connected to the second metal sheet 16. The first metal sheet 15, the indicator light 14, the first power supply 12, the second metal sheet 16 and the first wire 20 together constitute as follows Figure 6 The signal display circuit shown in the figure, wherein the indicator light 14 and the first power supply 12 are fixedly connected to the upper end surface of the profile frame 19, the first power supply 12 adopts a dry cell, when the handle 2 drives the fixing rod 3 to slide forward, when the right end of the fixing rod 3 contacts the profile frame 19, the limit block 6 fixes the position of the handle 2 and the fixing rod 3, and the first metal sheet 15 contacts the second metal sheet 16, Figure 6 The circuit shown is turned on, and the indicator light 14 lights up; a travel switch 11 located at the front end of the moving rod 4 is also fixedly connected inside the fixed rod 3, and the travel switch 11 adopts a normally open structure, and the switch button is located directly in front of the moving rod 4. A second power supply 13 is also fixedly connected to the upper front of the insulating housing 1, and the third metal sheet 17, the travel switch 11, the second power supply 13 and the fourth metal sheet 18 are connected in series in sequence through the second wire 21 to form a circuit as shown in FIG. Figure 7 In the polarity detection circuit shown in FIG. 1 , the second wire 21 is located inside the corresponding structure when the fixed rod 3 and the molded frame 19 are in position. When the second rod 502 is pushed upward, the moving rod 4 slides forward and contacts the switch button of the travel switch 11, so that Figure 7 The circuit shown is conducting.

[0030] The operating steps of this device are as follows:

[0031] (1) First, connect a milliampere ammeter in series to the output terminals L and N of the zero-sequence current transformer (the output terminals L and N of the zero-sequence current transformer will each lead a wire to the terminal block in the secondary equipment area. Connecting the ammeter in series here can keep a safe distance from the running cable without any danger). L is connected to the positive pole of the ammeter and N is connected to the negative pole of the ammeter to indicate the direction of current deflection during the polarity test.

[0032] (2) Nest the rectangular ring on the top of the device into the zero-sequence current transformer.

[0033] (3) Push the handle 2 and the fixing rod 3 to the working position and lock them in the position of the limit block 6. At this time, the right end of the fixing rod 3 presses the groove on the inner wall of the right end of the molded frame 19, and the indicator light 14 turns on.

[0034] (4) Lift the push rod 5 upward and release it. The front end of the moving rod 4 touches the travel switch 11, and the normally open contact of the travel switch is instantly closed. At this time, the polarity test circuit is suddenly turned on, generating a sudden current.

[0035] (5) Observe the deflection direction of the milliammeter pointer. If the pointer is deflected in the positive direction, it means that the polarity of the zero-sequence current transformer is correct; otherwise, it means that the polarity of the zero-sequence current transformer is incorrect.

[0036] (6) Move the handle 2 and the fixing rod 3 to the left, reset all the parts, and then remove the rectangular ring on the top of the device from the zero-sequence current transformer. This completes a live test of the polarity of the zero-sequence current transformer. To ensure the accuracy of the polarity test, steps (4) and (5) can be repeated 2-3 times to strengthen and verify the test conclusions.

[0037] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements can be made without departing from the principle of the present invention. These improvements should also be regarded as the protection scope of the present invention.

Claims

1. A portable zero-sequence current transformer live test device, characterized in that: It includes an insulating shell, a fixed rod slidably connected to the inside of the insulating shell along the length direction of the insulating shell, a handle fixedly connected to the rear end of the fixed rod, a movable rod coaxially distributed with the fixed rod and sliding along the length direction of the fixed rod, a shaped frame fixedly connected to the front of the insulating shell, and a signal display circuit and a polarity detection circuit arranged between the shaped frame and the fixed rod. The signal display circuit is composed of a first metal sheet, a first power supply, an indicator light and a second metal sheet connected in series in sequence through a first wire, the first metal sheet is fixedly connected to the front end face of the fixed rod, the second metal sheet is fixedly connected to the shaped frame and the position is distributed corresponding to the first metal sheet, one end of the first wire is fixedly connected to the first metal sheet, and after being connected to the first power supply and the indicator light in sequence, the other end is fixedly connected to the second metal sheet; the polarity detection circuit is composed of a third metal sheet, a travel switch, a second power supply and a fourth metal sheet connected in series in sequence through a second wire, the travel switch is fixedly connected to the front part of the inside of the fixed rod, the third metal sheet is fixedly connected to the front end face of the fixed rod, and the fourth metal sheet is fixedly connected to the shaped frame and the position is distributed corresponding to the third metal sheet; When the fixed rod slides forward and the front end is in contact with the shaped frame, the first metal sheet is connected to the second metal sheet, the third metal sheet is connected to the fourth metal sheet, the travel switch is normally open, and when the moving rod moves forward, the front end of the moving rod touches the travel switch button, and the travel switch is closed. A sliding seat is also provided at the rear end of the insulating shell below the handle, and the sliding seat is fixedly connected to the bottom of the rear end of the insulating shell and has a sliding groove inside. The lower end of the handle is connected to the sliding groove for sliding back and forth, and a push rod for pushing the moving rod to slide forward is connected to the rear end of the moving rod.

2. The portable zero-sequence current transformer live testing device according to claim 1, characterized in that: The first conducting wire is distributed along the inside of the fixing rod and the inside of the shaped frame, and the first power supply and the indicator light are both fixedly connected to the shaped frame.

3. The portable zero-sequence current transformer live testing device according to claim 1, characterized in that: The second conducting wire is distributed inside the fixing rod and the profile frame, and the second power source is fixedly connected to the insulating shell.

4. The portable zero-sequence current transformer live testing device according to claim 1, characterized in that: A first spring with an axis distributed along the front-to-back direction is arranged between the front end of the handle and the sliding seat.

5. The portable zero-sequence current transformer live testing device according to claim 1 or 4, characterized in that: A height-adjustable limiting block is arranged at the rear end of the sliding groove on the sliding seat.

6. The portable zero-sequence current transformer live testing device according to claim 5, characterized in that: The front end of the limit block is connected to the upper surface of the sliding groove through a compression spring, the rear end of the limit block is hinged to the upper surface of the sliding groove, and the front end of the upper end of the limit block is located above the lower end of the handle in a normal state.

7. The portable zero-sequence current transformer live testing device according to claim 1, characterized in that: The handle is in a rectangular frame structure, and the rear end of the moving rod passes through the front end of the handle and is located inside the handle and is hinged to the push rod. The push rod consists of a first rod body fixedly connected to a second rod body behind the first rod body, the first rod body is inclined downward from the back to the front, the front end of the first rod body is hinged to the handle and can be rotated upward along the inner wall of the handle, the second rod body is inclined upward from the back to the front, the second rod body and the first rod body are distributed at a certain angle, and the moving rod is hingedly connected to the first rod body and the second rod body at the connection point.

8. The portable zero-sequence current transformer live testing device according to claim 7, characterized in that: A return spring is arranged between the first rod body and the handle.

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