CN114264880B - Transformer test wiring change-over switch - Google Patents
Transformer test wiring change-over switch Download PDFInfo
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- CN114264880B CN114264880B CN202111577717.9A CN202111577717A CN114264880B CN 114264880 B CN114264880 B CN 114264880B CN 202111577717 A CN202111577717 A CN 202111577717A CN 114264880 B CN114264880 B CN 114264880B
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Abstract
The invention relates to the field of power equipment, in particular to a transformer test wiring transfer switch, which comprises a test correction module (300), wherein the test correction module (300) comprises a multiplexer (310) and a plurality of compensation resistors (320) connected with the multiplexer (310), and the output end of the multiplexer (310) is connected with a measurement side lead terminal (120) in parallel; when measuring the DC resistance of the transformer, the corresponding compensation resistor (320) is selected by the multiplexer (310) according to the grade and capacity of the transformer and connected to the measuring side lead terminal (120). The invention reduces the overall resistance by incorporating a large compensation resistor, thereby reducing the impact of contact resistance. The invention can improve the accuracy of the test. Meanwhile, wiring and switching can be facilitated, the labor intensity of workers in climbing up and down is reduced, and the testing efficiency is improved.
Description
Technical Field
The invention relates to the field of power equipment, in particular to a transformer test wiring change-over switch.
Background
The measurement of the DC resistance of the winding of the power transformer is one of the main items of transformer delivery and preventive tests, and meanwhile, the test must be carried out in the manufacturing process, after major repair, handover test, fault diagnosis and the like of the transformer and the accurate measurement of the DC resistance of the winding is very important. By measuring the direct current resistance, the welding quality inside the winding, whether the contact of each position of the tapping switch is good, whether the winding or the outgoing line has break parts, whether the winding has turn-to-turn, interlayer short circuit and the like can be checked. At present, a common transformer direct current resistance tester can only adopt four-terminal method wiring test when measuring the resistance of winding wires. Therefore, the test of AB, BC and CA is needed to be completed three times when the resistance of the winding wire is measured, and a special person is needed to switch the test wire clamp between three phases. The operation is troublesome, the time consumption is relatively long, errors caused by human factors are very easy to occur when the tester with low field experience operates, and once the error occurs in wiring, the time consumption is relatively long. Moreover, the operators need to climb the transformer back and forth to easily fall off from high altitude and get an electric shock accident, so that the safety is required to be improved. In the prior art, the switching of the circuit can be realized by using the existing change-over switch, but no matter what type of change-over switch is adopted or jumper wires are used for connection, certain contact resistance can be generated. Thus, although the prior art is convenient to test, the accuracy of the direct current resistance is reduced. Therefore, designing a transformer test wiring transfer switch which is convenient to switch and can improve the test precision becomes an urgent requirement.
Disclosure of Invention
The invention aims to solve the technical problems that: the transformer test wiring change-over switch is convenient to switch and capable of improving test accuracy.
The technical scheme for solving the technical problems is as follows: the utility model provides a transformer test change over switch that connects, includes box body and sets up transformer side lead wire terminal, measurement side lead wire terminal and change over switch on the box body, its characterized in that: the test correction module comprises a multiplexer and a plurality of compensation resistors connected with the multiplexer, and the output end of the multiplexer is connected with the lead terminal at the measuring side in parallel; when measuring the DC resistance of the transformer, the corresponding compensation resistance is selected by a multiplexer according to the grade and capacity of the transformer and connected to the lead terminal at the measuring side.
Preferably, the change-over switch includes: the upper end is provided with a handle, the lower end is provided with a switching rotating shaft of a trigger rod, and the middle part of the trigger rod is connected with the lower part of the switching rotating shaft; eight combined contacts uniformly distributed along the circumferential direction, wherein the combined contacts comprise a movable contact and a fixed contact; the movable contacts of the three upper combined contacts are connected with the positive electrode of the measuring side lead terminal, and the static contacts of the three upper combined contacts are sequentially connected with the phase A, the phase B and the phase C of the transformer side lead terminal in a clockwise direction; the movable contacts of the three combined contacts at the lower part are connected with the negative electrode of the lead terminal at the measuring side, and the static contacts of the three combined contacts at the lower part are sequentially connected with the phase B, the phase C and the phase A of the lead terminal at the transformer side in a clockwise direction; the two symmetrical combined contacts in the middle part are neutral gears; when the trigger rod rotates to a position of combining the contact, the movable contact is moved to the fixed contact and combined with the fixed contact to form a passage.
Preferably, the fixed contact of the combined contact is cylindrical, a circular movable contact clamping groove is formed in the upper portion of the fixed contact, and the lower portion of the fixed contact is fixedly connected with the bottom of the box body; the movable contact clamping groove is internally provided with metal tin; the change-over switch also comprises a movable contact fixed box which is tubular and is suspended at the upper part of the fixed contact, and the movable contact fixed box is fixedly connected with the box body through a bracket; the lower part of the movable contact fixed box is symmetrically provided with lead-out grooves; the upper part of the movable contact fixed box is symmetrically provided with clamping column leading-out grooves; the movable contact is arranged at the lower part of the inside of the movable contact fixed box, the upper part of the movable contact is provided with a pressing block, and the lower end of the pressing block is fixedly connected with the upper end of the movable contact through a pressing spring; the periphery of the movable contact is provided with a spiral heating groove; a heating coil is arranged in the spiral heating groove; the upper part of the pressing block is spherical; the pressing block is provided with a clamping column at a position corresponding to the clamping column leading-out groove, the outer side of the movable contact fixed box is provided with a bearing column, and a reset spring is arranged between the clamping column and the bearing column; the section of the trigger rod is semicircular, and the arc is arranged at the lower part; the inside heating control circuit that is equipped with of box body, heating control circuit and heating coil electrical connection.
Preferably, the heating coil is a heating resistance wire, and the heating control circuit comprises a switch and a fusing insurance;
or alternatively, the first and second heat exchangers may be,
the heating coil is an eddy current winding, and the heating control circuit is a high-frequency generator.
Preferably, the outside of the stationary contact is provided with a cooling fin, and the inside of the box body is provided with a cooling fan.
Preferably, the device also comprises a temperature sensor and a position switch, wherein the position switch is connected when the trigger rod rotates to the corresponding position, the position switch is connected with the heating coil in series, the heating control circuit starts the heating switch to heat the movable contact after detecting that the position switch is connected, and after the temperature reaches the set temperature, the heating switch is disconnected, at the moment, the tin melts to fuse the movable contact and the fixed contact into a whole, and then the cooling fan is started for refrigeration; starting the test when the room temperature is reached; after the test is finished, the heating switch is started to reach a specific temperature, the handle is rotated, and after the pressing block loses pressure, the movable contact is pulled out of the movable contact clamping groove under the action of the reset spring.
Preferably, a positioning mechanism is arranged on the periphery of the combined contact for positioning the trigger rod at the upper part of the pressing block.
Preferably, the test correction module further comprises a controller, a voltage acquisition module and a current acquisition module, wherein the voltage acquisition module and the current acquisition module are electrically connected with the controller, and the multiplexer is electrically connected with the controller; when the resistor is detected, the multiplexer selects the compensation resistor with the maximum resistance to be connected into the system, the direct current resistor and the contact resistor are detected and calculated, the controller selects the corresponding compensation resistor according to the direct current resistor and the contact resistor, and the voltage acquisition module and the current acquisition module are relieved.
Preferably, the box body is provided with a high-precision resistor connecting terminal, and the inner end of the high-precision resistor is electrically connected with the high-precision resistor; when testing the direct current resistor, connecting the connecting wire with a high-precision resistor connecting terminal to test the size of the contact resistor; and selecting a corresponding compensation resistor according to the size of the contact resistor and the model of the transformer.
Preferably, the box body is provided with an indicator lamp.
The beneficial effects of the invention are as follows:
1. the wiring and switching can be facilitated, the labor intensity of workers in climbing up and down is reduced, and the testing efficiency is improved.
2. The accuracy of the test can be improved.
Drawings
Fig. 1 is a schematic diagram of the principle of contact resistance compensation according to an embodiment of the present invention.
Fig. 2 is a schematic view of the appearance of an embodiment of the present invention.
Fig. 3 is a schematic view of a switching device for removing a cartridge according to an embodiment of the present invention.
Fig. 4 is a dynamic and static contact explosion diagram of a combined contact according to an embodiment of the present invention.
Fig. 5 is a schematic diagram of a moving contact heating control circuit according to an embodiment of the present invention.
Fig. 6 is a schematic diagram of a moving contact heating control circuit according to an embodiment of the present invention.
Fig. 7 is a schematic diagram of a moving contact heating control system according to an embodiment of the present invention.
Fig. 8 is a schematic view of a stationary contact of an embodiment of a bonding contact of the present invention.
Fig. 9 is a schematic view of one embodiment of a bonding contact of the present invention.
In the figure:
292b, closing the position switch; 292a, actuating a position switch; 520. a current collection module; 510. a voltage acquisition module; 500. a controller; 430. a permanent magnet; 420. a transverse support bar; 410. a vertical fixing column; 292. a position switch; 291. a temperature sensor; 232. a heat sink; 262. a return spring; 243. a receiving column; 251. a clamping column; 270. a heating coil; 221. a spiral heating groove; 261. a compression spring; 250. pressing the blocks; 242. the clamping column is led out of the groove; 241. a wire leading-out groove; 240. a movable contact fixed box; 231. a movable contact clamping groove; 230. a stationary contact; 220. a movable contact; 211. a trigger lever; 210. switching the rotating shaft; 320. a compensation resistor; 310. a multiplexer; 300. a test correction module; 200. a change-over switch; 120. a measurement-side lead terminal; 110. and a transformer side lead terminal.
Detailed Description
In order to make the technical scheme and beneficial effects of the present invention clearer, the following further explain the embodiments of the present invention in detail.
A transformer test wiring change-over switch comprises a box body. The box body is used for installing and placing the electric components. The transformer side lead terminal 110, the measurement side lead terminal 120, and the change-over switch 200 are provided inside the case, and the transformer side lead terminal 110, the tab of the measurement side lead terminal 120, and the handle of the change-over switch 200 are fixedly installed on the panel of the case for easy operation.
In order to improve the accuracy of the test and reduce the influence of the contact resistance, a compensation resistor 320 needs to be connected in parallel to the measurement-side lead terminal 120. Since the dc resistances of different transformers are different, the size of the compensation resistor 320 needs to be adjusted according to the transformers. Test correction module 300 is provided to facilitate adjustment of the present invention.
The test correction module 300 includes a multiplexer 310 and a plurality of compensation resistors 320 connected to the multiplexer 310, wherein an output terminal of the multiplexer 310 is connected in parallel with the measurement side lead terminal 120. A more common multiplexer may employ a gear adjustment switch, i.e., a multi-gear conventional fan speed switch. Or the multiplexer is a selection matrix formed by a plurality of self-holding button switches, each button switch is connected with a compensation resistor, and the corresponding button switch is pressed down according to the size of the transformer. A controllable multiplexer chip can also be selected, in conjunction with a microcontroller and a selection button, to select the compensation resistor 320.
At this time, when measuring the direct current resistance of the transformer, the corresponding compensation resistor 320 is selected by the multiplexer 310 according to the level and capacity of the transformer and is connected to the measurement side lead terminal 120. The principle is as follows:
the two resistors are connected in parallel, and the resistance value of the connected resistors is smaller than that of any resistor. As shown in the following table, the first row represents the magnitude of the parallel-connected compensated resistor in kΩ, and the first column represents the resistance of the resistor to be tested in Ω. The other areas are the differences between the resistor to be measured and the resistor to be measured after the resistor to be measured is integrated with the compensation resistor. Wherein the resistor to be measured comprises an actual resistor and a contact resistor. The difference between the value measured resistance and the value after parallel compensation resistance in the table is defined as the calculated error value. The size of the contact resistance can be calculated by loading a precision resistance test, and the contact resistance is matched with the calculated error value in the following table. Therefore, the absolute value of the difference value and the contact resistance difference value is within 0.1, and the compensation resistor can be used. The above 0.1 can be used as a matching threshold, and a compensation resistor can be taken between 31 and 40 by adjusting the matching threshold, so that the number of the compensation resistors can be reduced.
If the matching threshold is set to 0.1, the contact resistance is Rj, the calculated error value is Rc, and the calculated error value can be used as the compensation resistance when the absolute value of Rj-Rc is less than or equal to 0.1. At this time, if the contact resistance is tested to be 0.1Ω, 10kΩ may be selected when the resistance to be measured is between 31 and 40. The number of compensation resistors can be reduced at this time.
In the above table, the option area of the compensation resistor is thickened when Rj-rc=0.01. A compensation resistance can be set at about 4 ohms apart.
More preferably, the effect of reducing contact resistance is achieved. The change-over switch 200 is modified. The change-over switch 200 includes a switching shaft 210 and a combined contact including a moving contact 220 and a stationary contact 230.
For convenience of operation, a handle is provided at the upper end of the switching shaft 210. The bottom of the switching shaft 210 and the bottom of the inside of the case are fixed by bearing fixing seats, the upper part is rotatably connected with the upper part of the case, and the upper end passes through the case to protrude to the outside of the case and is provided with a handle. A trigger lever 211 is installed in the middle of the switching shaft 210, the trigger lever 211 has a strip structure, and the middle of the trigger lever 211 is fixedly connected with the switching shaft 210. The trigger lever 211 is used to contact the start contact 220 and the stationary contact 230.
Since the three terminals are tested two by two, six combined contacts can be provided to achieve the above-described switching, i.e., upper three and lower three. In this embodiment, to show the neutral position, eight combined contacts are provided, wherein the combined contact in the middle is not connected to any wire, but is only used to stop the neutral position.
Wherein the movable contact 220 of the upper three combined contacts is connected with the positive electrode of the measuring side lead terminal 120, and the stationary contact 230 of the upper three combined contacts is sequentially connected with the phase A, the phase B and the phase C of the transformer side lead terminal 110 in the clockwise direction. The movable contact 220 of the lower three combined contacts is connected to the negative electrode of the measurement side lead terminal 120, and the stationary contact 230 of the lower three combined contacts is sequentially connected to the B phase, the C phase, and the a phase of the transformer side lead terminal 110 in the clockwise direction.
The bottom of the trigger lever 211 is lower than the upper end of the movable contact 220, the lower part of the trigger lever 211 is set to be an arc surface, the upper part of the movable contact 220 is set to be an arc surface, the two can be abutted, and when the trigger lever 211 moves to the position of the movable contact 220, the movable contact 220 is pressed downwards until the movable contact 220 is combined with the stationary contact 230. When the trigger lever 211 is rotated to the position of the combined contact, the movable contact 220 is moved toward the stationary contact 230 and combined with the stationary contact 230 to form a path, and the two-phase lead of the transformer is connected to the positive and negative poles of the test device.
The movable contact 220 may be configured as a spring, as shown in fig. 9, wherein the movable contact 220 is inverted V-shaped, one end of the movable contact is fixedly installed inside the case, and the other end of the movable contact is provided with a coupling portion coupled with the stationary contact 230, and in order to achieve large-area contact, the contact portion is configured as a flat plate shape matched with the stationary contact 230. With stationary contact 230 in the lower portion. In the drawing, the movable contact 220 is separated from the stationary contact 230 when the trigger lever 211 is not moved to the top of the movable contact 220, and the movable contact 220 is pressed downward to be combined with the stationary contact 230 when the trigger lever 211 is moved to the top of the movable contact 220. When the trigger lever 211 moves to other positions, the movable contact 220 is restored to the original position by its own elasticity, and the movable contact 220 is separated from the stationary contact 230.
Better, in order to reduce the contact resistance, the connection of the movable contact and the fixed contact is realized by adopting a welding mode during testing. In this embodiment, the movable contact 220 is configured as a column, and a movable contact clamping groove 231 is disposed on the upper end surface of the column, and accordingly, the cross-sectional shape of the lower end of the stationary contact 230 is the same as that of the movable contact clamping groove 231, so as to achieve the combination of the movable contact 220 and the stationary contact 230. In this embodiment, the stationary contact 230 of the combined contact is a cylinder, the upper part of the stationary contact 230 is provided with a circular movable contact clamping groove 231, and the lower part of the stationary contact 230 is fixedly connected with the bottom of the box body; the movable contact card slot 231 is internally provided with metallic tin. When the lower end of the movable contact 220 is released from the bottom of the movable contact clamping groove 231, the movable contact or the stationary contact is heated to melt the metal tin, so that the movable contact and the stationary contact are fused better. Preferably, in order to facilitate separation at the time of separation, a heating means is provided at an upper portion of the movable contact 220.
In order to fix the movable contact 220, the change-over switch 200 further includes a movable contact fixing case 240. The movable contact fixed box 240 is tubular and is suspended at the upper part of the stationary contact 230, and the movable contact fixed box 240 is fixedly connected with the box body through a bracket. The support comprises vertical fixed columns 410 arranged outside the movable contact 220, transverse support rods 420 are arranged on two sides of the vertical fixed columns 410, one ends of the two transverse support rods 420 are fixedly connected with the vertical fixed columns 410, and the other ends of the two transverse support rods 420 are fixedly connected with the movable contact fixed box 240. The lower part of the movable contact fixing case 240 is symmetrically provided with a wire drawing groove 241; the upper part of the movable contact fixing box 240 is symmetrically provided with a clamping column leading-out groove 242.
The movable contact 220 is disposed at the lower part of the inside of the movable contact fixed box 240, a pressing block 250 is disposed at the upper part of the movable contact 220, and the lower end of the pressing block 250 is fixedly connected with the upper end of the movable contact 220 through a pressing spring 261.
A spiral heating groove 221 is formed on the periphery of the movable contact 220; the spiral heating groove 221 is internally provided with a heating coil 270. The heating coil 270 is a heating resistance wire, and the heating control circuit includes a switch and a fusing fuse. The heating resistance wire is controlled to heat by the switch to heat the movable contact 220. Preferably, for automatic control, a temperature sensor 291 and a position switch 292 are also included. The position switch 292 may be provided on the bracket or may be provided at a position corresponding to the position of the stationary contact through the bracket. For example, the position switch 292 is fixedly installed on a side surface of the movable contact fixing case 240 near the switching shaft 210 while maintaining a height corresponding to the trigger lever 211, or a trigger module is provided at an upper portion of the trigger lever 211. The position switch may be a travel switch, a proximity switch, or the like.
When the trigger lever 211 rotates to a corresponding position, the position switch 292 is turned on, the position switch 292 is connected with the heating coil 270 in series, the heating control circuit detects that the position switch 292 is turned on and then starts the heating switch to heat the movable contact 220, after the temperature reaches a set temperature, the heating switch is turned off, at the moment, the tin melts to melt the movable contact and the movable contact into a whole, and then the cooling fan is started to refrigerate.
Or the position switch 292 may be disposed at an upper portion of the vertical fixing column 410, the position switch may be an inductive switch, and a temperature sensor may be installed on the stationary contact 230, and after the stationary contact reaches the melting temperature of tin, it may be determined that the tin has melted. The temperature sensor may employ a temperature controlled relay or a microcontroller may be provided. When the temperature control relay is adopted, the position switch can be provided with two position switches, one position switch is used for heating and fusing before testing, and the other position switch is used for heating and releasing the fusion after testing, so that the heating control circuit can be realized by adopting the relay.
When a relay is used, as shown in fig. 5, the relay K1 is a relay for controlling the heating coils 270, and each heating coil 270 is provided with a relay and a position switch 292. Wherein the position switch may provide an on switch and an off switch, wherein the on position switch 292a is used to effect the on and off position switch 292b is used to turn off the control circuit. Wherein the off position switch 292b employs its normally closed contact as a control switch. The circuit diagram is shown in fig. 5. Preferably, for ease of control, an actuation button may be provided, which is serially connected in the circuit of fig. 5. When the gear is rotated to a specific gear, the start button is pressed to start heating, and heating is stopped after the gear reaches a specific temperature.
When the control circuit manufactured by micro control is adopted for control, the circuit structure is simpler, and the system block diagram is shown in fig. 6. The controller 500 collects the position signals of the respective position switches 292 and the temperature of the temperature sensor 291, and sets a control program to control the heating coil 270 using the above-described control logic.
Wherein the heating coil 270 may be an eddy current winding, and correspondingly, the heating control circuit is provided with a high frequency generator in addition to the control circuit. Wherein the high frequency power source generator supplies power to the heating coil as a power source.
To facilitate pressing, the upper portion of the pressing block 250 is spherical; the pressing block 250 is provided with a clamping post 251 corresponding to the clamping post leading-out groove 242. The locking post 251 slides up and down in the locking post extraction groove 242. The outer side of the movable contact fixing case 240 is provided with a receiving post 243, and a return spring 262 is provided between the clamping post 251 and the receiving post 243. When the trigger lever 211 presses the pressing block 250, the pressing block 250 descends and presses the movable contact 220 downward by the pressing spring 261. After the force of the trigger lever 211 is lost, the pressing block 250 is lifted up by the force of the return spring 262, and the movable contact is pulled out of the movable contact clamping groove 231 by the pressing spring 261. Accordingly, the cross-section of the trigger lever 211 is semicircular, and the arc is at the lower part. A heating control circuit is provided inside the case body, and is electrically connected to the heating coil 270.
With the above scheme, after the trigger lever 211 releases the pressing of the pressing block 250, the moving contact is moved upward by the tension of the spring, at this time, the tin still adheres to the moving contact in the melting process, under the action of the tension, the moving contact 220 can be pulled out instantaneously when the tension threshold is reached, and the separation of the moving contact and the fixed contact can be ensured.
Preferably, in order to reduce the influence of temperature on the resistance, as shown in the figure, the outside of the stationary contact 230 is provided with a cooling fin 232, and the inside of the box body is provided with a cooling fan. Starting a test when the combined contact reaches room temperature by a cooling fan; after the test is completed, the heating switch is started to reach a specific temperature, the handle is turned, and after the pressing block 250 loses pressure, the movable contact 220 is pulled out of the movable contact clamping groove 231 under the action of the return spring 262.
Better, in order to achieve accurate positioning of the gear. A positioning mechanism is provided on the outer periphery of the bonding contact, positions the trigger lever 211 at the position of the bonding contact, and holds the trigger lever 211 at the upper portion of the pressing block 250.
If a permanent magnet is disposed on the vertical fixing column 410 corresponding to the movable contact fixing box 240, a metal iron block is disposed at the end of the trigger lever 211. The positioning mechanism may be a permanent magnet 430, the permanent magnet 430 is disposed at the upper end of the vertical fixing column 410, and the height of the permanent magnet is consistent with the height of the trigger lever 211, when the trigger lever 211 rotates to be coincident with the movable contact point, an attractive force is applied to the trigger lever to prompt the operator that the operator is in place. Correspondingly, the end part of the trigger rod can be provided with a magnet or a magnetic conductive material such as metal iron. When the trigger lever reaches the position of the movable contact 220, an attractive force is felt, which in turn can alert the operator that it is in place.
Or the gear is fixed by adopting an elastic ball. A ball is inserted into the vertical fixing column 410, a spring is installed inside the ball, and a portion of the ball protrudes to the outside of the vertical fixing column 410. The end of the trigger lever 211 is provided with a groove, and when the groove of the trigger lever is overlapped with the position of the ball, the groove and the ball are locked, so that the positioning is realized.
Further, in order to achieve accurate measurement, a test correction module may also be provided in this embodiment. The test correction module further includes a controller 500, a voltage acquisition module 510, and a current acquisition module 520. The voltage acquisition module 510 and the current acquisition module 520 are electrically connected to the controller 500, and the multiplexer 310 is electrically connected to the controller 500.
When detecting the resistance, the multiplexer 310 selects the compensation resistance 320 with the maximum resistance value to be connected into the system, detects and calculates the direct current resistance and the contact resistance, and the controller 500 selects the corresponding compensation resistance according to the direct current resistance and the contact resistance, and releases the voltage acquisition module 510 and the current acquisition module 520. Through the preliminary detection of the invention, the direct current resistance can be roughly tested, and the size of the compensation resistance is determined according to the determination method of combining the direct current resistance and the contact resistance with the compensation resistance. And further, accurate measurement results are achieved when the test device is used for testing.
The contact resistance is a rough value and varies accordingly according to different environments. Therefore, when the device is used, the size of the contact resistance can be determined through detection of the device, if the difference value between the detected contact resistance and the calibrated contact resistance is within a controllable range, correction is not needed, and if the difference value is large, correction is needed. The result of the correction is now mainly a reduction of environmental impact, since the contact resistance will also vary in magnitude in different temperature environments. At this time, the box body is provided with a high-precision resistor connection terminal, and the inner end of the high-precision resistor connection is electrically connected with the high-precision resistor. The resistance value of the high-precision resistor may be set to 1Ω, 10Ω, 100deg.C, or the like.
When testing the direct current resistor, the connecting wire is connected with the high-precision resistor connecting terminal at first, and the size of the contact resistor is tested. And then selecting a corresponding compensation resistor according to the size of the contact resistor and the model of the transformer. At this time, if the electric power enters the inside of the high-altitude substation, the temperature and humidity are different, and the error of the contact resistance may be large, so that correction is required. The compensation resistance is selected according to the actual contact resistance. The appropriate resistance may be selected by means of a look-up table based on the allowable error range.
Further, in order to clearly indicate which direct current resistor is between the two phases currently detected, an indicator light is arranged on the box body. The indicator lights respectively indicate AB phase, BC phase and CA phase. When the trigger rod triggers the corresponding combined contact, the position signal is detected by an inductive switch, a position switch and the like, and the corresponding indicator lamp is lightened according to the position signal.
In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and the related workers can make various changes and modifications without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the description, but includes all equivalent changes and modifications in shape, construction, characteristics and spirit according to the scope of the claims.
Claims (8)
1. The utility model provides a transformer test change-over switch that connects, includes box body and sets up transformer side lead terminal (110), measurement side lead terminal (120) and change-over switch (200) on the box body, its characterized in that:
the system further comprises a test correction module (300), wherein the test correction module (300) comprises a multiplexer (310) and a plurality of compensation resistors (320) connected with the multiplexer (310), and the output end of the multiplexer (310) is connected with the measurement side lead terminal (120) in parallel;
when measuring the direct current resistance of the transformer, selecting a corresponding compensation resistor (320) through a multiplexer (310) according to the grade and the capacity of the transformer and connecting the compensation resistor to a lead terminal (120) at the measuring side;
the change-over switch (200) comprises:
the upper end is provided with a handle, the lower end is provided with a switching rotating shaft (210) of a trigger lever (211), and the middle part of the trigger lever (211) is connected with the lower part of the switching rotating shaft (210);
eight combined contacts uniformly distributed along the circumferential direction, wherein the combined contacts comprise a movable contact (220) and a fixed contact (230);
the movable contact (220) of the upper three combined contacts is connected with the positive electrode of the measuring side lead terminal (120), and the static contact (230) of the upper three combined contacts is sequentially connected with the phase A, the phase B and the phase C of the transformer side lead terminal (110) in the clockwise direction;
the movable contact (220) of the three combined contacts at the lower part is connected with the negative electrode of the measuring side lead terminal (120), and the static contact (230) of the three combined contacts at the lower part is sequentially connected with the phase B, the phase C and the phase A of the transformer side lead terminal (110) in the clockwise direction;
the two symmetrical combined contacts in the middle part are neutral gears;
when the trigger lever (211) rotates to a position of combining the contacts, the movable contact (220) is moved to the fixed contact (230) and combined with the fixed contact (230) to form a passage;
the fixed contact (230) of the combined contact is cylindrical, a circular movable contact clamping groove (231) is formed in the upper portion of the fixed contact (230), and the lower portion of the fixed contact (230) is fixedly connected with the bottom of the box body; the movable contact clamping groove (231) is internally provided with metallic tin;
the change-over switch (200) further comprises a movable contact fixed box (240), wherein the movable contact fixed box (240) is tubular and is suspended at the upper part of the fixed contact (230), and the movable contact fixed box (240) is fixedly connected with the box body through a bracket; the lower part of the movable contact fixed box (240) is symmetrically provided with a wire leading-out groove (241); the upper part of the movable contact fixed box (240) is symmetrically provided with clamping column leading-out grooves (242);
the movable contact (220) is arranged at the lower part of the inside of the movable contact fixed box (240), a pressing block (250) is arranged at the upper part of the movable contact (220), and the lower end of the pressing block (250) is fixedly connected with the upper end of the movable contact (220) through a pressing spring (261); a spiral heating groove (221) is formed in the periphery of the movable contact (220); a heating coil (270) is arranged in the spiral heating groove (221);
the upper part of the pressing block (250) is spherical; a clamping column (251) is arranged at the position of the pressing block (250) corresponding to the clamping column leading-out groove (242), a bearing column (243) is arranged at the outer side of the movable contact fixed box (240), and a reset spring (262) is arranged between the clamping column (251) and the bearing column (243);
the section of the trigger rod (211) is semicircular, and the arc is arranged at the lower part;
the inside of the box body is provided with a heating control circuit which is electrically connected with a heating coil (270).
2. The transformer test wiring transfer switch of claim 1, wherein:
the heating coil (270) is a heating resistance wire, and the heating control circuit comprises a switch and a fusing insurance;
or alternatively, the first and second heat exchangers may be,
the heating coil (270) is an eddy current winding, and the heating control circuit is a high frequency generator.
3. A transformer test wiring transfer switch as described in claim 2, wherein:
and a cooling fin (232) is arranged on the outer side of the stationary contact (230), and a cooling fan is arranged in the box body.
4. A transformer test wiring transfer switch as described in claim 3, wherein:
the temperature sensor (291) and the position switch (292) are also included, when the trigger rod (211) rotates to the corresponding position, the position switch (292) is turned on, the position switch (292) is connected with the heating coil (270) in series, the heating control circuit starts the heating switch to heat the movable contact (220) after detecting that the position switch (292) is turned on, and after reaching the set temperature, the heating switch is turned off, at the moment, the tin melts to fuse the movable contact and the movable contact into a whole, and then the cooling fan is started for refrigeration;
starting the test when the room temperature is reached;
after the test is finished, the heating switch is started to reach the set temperature, the handle is rotated, and after the pressing block (250) loses pressure, the movable contact (220) is pulled out of the movable contact clamping groove (231) under the action of the reset spring (262).
5. The transformer test wiring transfer switch of claim 4, wherein:
the periphery of the combined contact is provided with a positioning mechanism for positioning the trigger lever (211) at the upper part of the pressing block (250).
6. The transformer test wiring transfer switch of claim 1, wherein:
the test correction module further comprises a controller (500), a voltage acquisition module (510) and a current acquisition module (520), wherein the voltage acquisition module (510) is electrically connected with the current acquisition module (520) and the controller (500), and the multiplexer (310) is electrically connected with the controller (500);
when the resistance is detected, the multiplexer (310) selects the compensation resistance (320) with the maximum resistance value to be connected into the system, the direct current resistance and the contact resistance are detected and calculated, the controller (500) selects the corresponding compensation resistance according to the direct current resistance and the contact resistance, and the voltage acquisition module (510) and the current acquisition module (520) are released.
7. The transformer test wiring transfer switch of claim 6, wherein:
the box body is provided with a high-precision resistor connecting terminal, and the inner end of the high-precision resistor connecting terminal is electrically connected with the high-precision resistor;
when testing the direct current resistor, connecting the connecting wire with a high-precision resistor connecting terminal to test the size of the contact resistor;
and selecting a corresponding compensation resistor according to the size of the contact resistor and the model of the transformer.
8. A transformer test wiring transfer switch as described in any one of claims 1-7, wherein:
an indicator light is arranged on the box body.
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