Dynamic arc extinguishing device of transformer direct current resistance tester

Abstract

A dynamic arc extinguishing device of a transformer direct current resistance tester comprises a measuring circuit, an arc extinguishing circuit and an acquisition circuit. Wherein the arc extinction circuit is connected in series with the acquisition circuit and is connected in parallel with the measurement circuit; the measuring circuit is a conducting circuit when the direct current resistance tester works normally and is used for measuring the direct current resistance of the transformer winding; when the arc extinguishing circuit is used for disconnecting the switch and ending measurement, arc extinguishing is carried out on back electromotive force generated by a transformer winding so as to protect original circuits in the circuit; the acquisition circuit is used for acquiring real-time current and voltage of the arc extinction circuit and feeding back the real-time current and voltage to the single-chip microcomputer, and then adjusting voltage is output to grid voltage of the field effect diode through the digital-to-analog conversion module, so that the arc extinction current is adjusted, and the dynamic arc extinction function is achieved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the electric power equipment measurement technical field, concretely relates to a dynamic arc extinguishing device of transformer direct resistance tester. BACKGROUND

[0002] The transformer direct current resistance test is carried out during the factory test, power failure detection and preventive test of power transformer, one end of the direct resistance tester is connected with the winding terminal of the transformer, after the direct resistance measurement ends, the inductance component on the winding of the transformer can produce a counter electromotive force, and the arc extinguishing circuit is needed to extinguish the arc operation of the counter electromotive force. Since the inductance of transformers of different capacities has obvious difference, the arc current extinguished by the existing arc extinguishing circuit is a fixed value, and the arc current size cannot be adjusted according to the electromotive force produced by different inductances of different transformers, so the arc extinguishing is insufficient or excessive, therefore, how to realize the real-time monitoring of the arc current and adjust the arc current size is the problem to be solved by the utility model. SUMMARY

[0003] The utility model solves the technical problem that a dynamic arc extinguishing device of transformer direct resistance tester can realize the real-time monitoring of the arc current and adjust the arc current size.

[0004] In order to solve the above technical problem, the utility model adopts the technical scheme of a dynamic arc extinguishing device of transformer direct resistance tester, which comprises a measurement circuit, an arc extinguishing circuit and an acquisition circuit, the arc extinguishing circuit is connected in series with the acquisition circuit and connected in parallel with the measurement circuit, the current flow acquisition circuit feeds back the real-time current and voltage to the single-chip microcomputer in the arc extinguishing circuit, and then the regulated voltage is output to the gate voltage of the field effect tube in the arc extinguishing circuit through the digital-analog conversion module in the arc extinguishing circuit.

[0005] The measurement circuit comprises a direct current circuit, an air switch, a measured transformer winding, the first end of the air switch is electrically connected with the positive pole of the direct current power line, the second end is electrically connected with the measured transformer winding, and the other end of the measured transformer winding is electrically connected with the negative pole of the direct current power line.

[0006] The arc extinguishing circuit comprises a unidirectional conduction diode, a field effect tube, a resistor, a digital-analog conversion module and a single-chip microcomputer, the first end of the resistor is electrically connected with the field effect tube, and the second end is electrically connected with the current sensor, the first end of the unidirectional conduction diode is connected with the air switch and the measured transformer winding in the measurement circuit, the second end is electrically connected with the field effect tube, one end of the digital-analog conversion module is electrically connected with one end of the single-chip microcomputer, the other end is electrically connected with the field effect tube, and the other end of the single-chip microcomputer is electrically connected with the current and voltage acquisition module.

[0007] The source electrode of the field effect tube is electrically connected with the second end of the unidirectional conducting diode, the drain electrode of the field effect tube is electrically connected with the resistor, and the gate electrode of the field effect tube is electrically connected with the other end of the digital-analog conversion module.

[0008] The acquisition circuit comprises a current sensor, a voltage sensor and a current-voltage acquisition module; the first end of the voltage sensor is electrically connected with the A end of the winding of the measured transformer, the second end is electrically connected with the B end of the winding of the measured transformer, and the third end is electrically connected with the first end of the current-voltage acquisition module; the first end of the current sensor is electrically connected with the resistor, the second end is electrically connected with the negative pole of the direct current circuit, and the third end is electrically connected with the second end of the current-voltage acquisition module; and the third end of the current-voltage acquisition module is electrically connected with the single-chip microcomputer.

[0009] The air switch is electrically connected to the main circuit and is connected in series with the direct current circuit.

[0010] The voltage sensor is connected in parallel with the winding of the measured transformer.

[0011] The main beneficial effects of the utility model lie in:

[0012] By acquiring the voltage at both ends of the winding of the transformer and the current data of the internal arc extinguishing circuit, the internal arc extinguishing current is monitored in real time.

[0013] The current sensor is used for measuring the current value in the loop in real time, and the voltage sensor is used for measuring the voltage value in the loop in real time; the two sensors return the real-time current and voltage data to the single-chip microcomputer through the current-voltage acquisition module; the single-chip microcomputer drives the digital-analog conversion module to control the on voltage of the gate electrode of the field effect tube according to the measured data, so as to control the arc current, thereby avoiding the problems of excessively long arc extinguishing current time or excessively large arc current causing the breakdown of circuit components. BRIEF DESCRIPTION OF DRAWINGS

[0014] The utility model will be further described in connection with the drawings and embodiments.

[0015] Figure 1 It is a structural schematic view of the utility model.

[0016] In the figure: direct current circuit 11;Air switch 12;Measured transformer winding 13;Unidirectional conducting diode 21;Field effect tube 22;Resistor 23;Digital-analog conversion module 24;Single-chip microcomputer 25;Current sensor 31;Voltage sensor 32;Current-voltage acquisition module 33. DETAILED DESCRIPTION

[0017] As Figure 1The application discloses a dynamic arc extinguishing device of a transformer direct resistance tester, which comprises a measuring circuit, an arc extinguishing circuit and a collecting circuit; the arc extinguishing circuit is connected in series with the collecting circuit and in parallel with the measuring circuit; the current flows through the collecting circuit and feeds back real-time current and voltage to a single-chip microcomputer 25 in the arc extinguishing circuit, and then outputs an adjusted voltage to a gate voltage of a field effect tube 22 in the arc extinguishing circuit through a digital-analog conversion module 24 in the arc extinguishing circuit; the arc extinguishing circuit is connected in parallel with the measuring circuit and is used for consuming and limiting arc current generated by counter electromotive force of a transformer winding 13; the arc extinguishing circuit is connected in series with the collecting circuit, obtains voltage from the collecting circuit and adjusts the voltage output to the gate voltage of the field effect tube 22, so that the arc current of the field effect tube 22 is adjusted, and arc current generated by counter electromotive force of different transformer windings is adapted and eliminated.

[0018] In the preferred scheme, the measuring circuit comprises a direct current circuit 11, an air switch 12 and the transformer winding 13; the first end of the air switch 12 is electrically connected with the positive pole of the direct current circuit 11, the second end is electrically connected with the transformer winding 13, and the other end of the transformer winding 13 is electrically connected with the negative pole of the direct current circuit 11; in normal operation, the measuring circuit is a conduction circuit for normal operation of the direct resistance tester, and the circuit measures direct resistance of the transformer winding 13.

[0019] In the preferred scheme, the arc extinguishing circuit comprises a unidirectional conducting diode 21, the field effect tube 22, a resistor 23, the digital-analog conversion module 24 and the single-chip microcomputer 25; the first end of the resistor 23 is electrically connected with the field effect tube 22, and the second end is electrically connected with a current sensor 31; the first end of the unidirectional conducting diode 21 is connected with the air switch 12 and the transformer winding 13 in the measuring circuit, and the second end is electrically connected with the field effect tube 22; one end of the digital-analog conversion module 24 is electrically connected with one end of the single-chip microcomputer 25, and the other end is electrically connected with the field effect tube 22; the other end of the single-chip microcomputer 25 is electrically connected with a current and voltage collecting module 33; the resistor 23 is used as a control element of arc current and is used for limiting current and stabilizing arc characteristics, so as to ensure normal operation of the device; the unidirectional conducting diode 21 controls switching of the arc extinguishing circuit by using the characteristics of reverse cut-off and forward conduction.

[0020] In the preferred scheme, the source of the field effect tube 22 is electrically connected with the second end of the unidirectional conducting diode 21; the drain of the field effect tube 22 is electrically connected with the resistor 23, and the gate of the field effect tube 22 is electrically connected with the other end of the digital-analog conversion module 24; the gate voltage input through the digital-analog conversion module 24 controls the drain current, so as to adjust the arc current and realize the dynamic arc extinguishing function.

[0021] In the preferred scheme, the acquisition circuit comprises a current sensor 31, a voltage sensor 32 and a current-voltage acquisition module 33; the voltage sensor 32 is electrically connected at a first end to the A end of the measured transformer winding 13, at a second end to the B end of the measured transformer winding 13 and at a third end to a first end of the current-voltage acquisition module 33; the current sensor 31 is electrically connected at a first end to the resistor 23, at a second end to the negative pole of the direct current circuit 11 and at a third end to a second end of the current-voltage acquisition module 33; the third end of the current-voltage acquisition module is electrically connected to the single-chip microcomputer 25; the current-voltage acquisition module 33 converts the current-voltage analog signals fed back by the current sensor 31 and the voltage sensor 32 into digital signals and sends the digital signals to the single-chip microcomputer 25, and then outputs the regulated voltage to the gate voltage of the field effect tube 22 through the digital-analog conversion module 24, so as to regulate the size of the arc-extinguishing current and realize the dynamic arc-extinguishing function.

[0022] In the preferred scheme, the air switch 12 is electrically connected to the main circuit and is connected in series with the direct current circuit 11, so that the air switch 12 serves as a general switch and can manually control the on-off of the circuit, thereby facilitating maintenance or emergency power-off.

[0023] In the preferred scheme, the voltage sensor 32 is connected in parallel with the measured transformer winding 13, so as to acquire the voltage across the winding L1 in real time and feed back to the current-voltage acquisition module.

[0024] The above-described embodiments are merely preferred technical solutions of the present application and should not be regarded as limiting the present application; the embodiments in the present application and the features in the embodiments can be combined with each other in the case of no conflict. The protection scope of the present application should be the technical solutions recited in the claims and the equivalent replacement solutions of the technical features recited in the claims. That is, the equivalent replacement and improvement within the scope should also be within the protection scope of the present application.

Claims

1. A dynamic arc suppression device for a transformer DC resistance tester, characterized in that: It includes a measurement circuit, an arc suppression circuit, and a data acquisition circuit; the arc suppression circuit is connected in series with the data acquisition circuit and in parallel with the measurement circuit. The current flow acquisition circuit feeds back the real-time current and voltage to the microcontroller (25) in the arc suppression circuit, and then outputs the regulated voltage to the gate voltage of the field-effect transistor (22) in the arc suppression circuit through the digital-to-analog converter module (24).

2. The dynamic arc suppression device of the transformer DC resistance tester according to claim 1, characterized in that: The measuring circuit includes a DC circuit (11), an air switch (12), and a transformer winding (13) under test. The first end of the air switch (12) is electrically connected to the positive terminal of the DC circuit (11), the second end is electrically connected to the transformer winding (13) under test, and the other end of the transformer winding (13) under test is electrically connected to the negative terminal of the DC circuit (11).

3. The dynamic arc suppression device of the transformer DC resistance tester according to claim 1, characterized in that: The arc suppression circuit includes a unidirectional conduction diode (21), a field-effect transistor (22), a resistor (23), a digital-to-analog converter module (24), and a microcontroller (25); the first end of the resistor (23) is electrically connected to the field-effect transistor (22), and the second end is electrically connected to the current sensor (31); the first end of the unidirectional conduction diode (21) is connected to the air switch (12) and the transformer winding (13) under test in the measurement circuit, and the second end is electrically connected to the field-effect transistor (22); one end of the digital-to-analog converter module (24) is electrically connected to one end of the microcontroller (25), and the other end is electrically connected to the field-effect transistor (22); the other end of the microcontroller (25) is electrically connected to the current and voltage acquisition module (33).

4. The dynamic arc suppression device of the transformer DC resistance tester according to claim 3, characterized in that: The source of the field-effect transistor (22) is electrically connected to the second terminal of the unidirectional diode (21); the drain of the field-effect transistor (22) is electrically connected to the resistor (23); and the gate of the field-effect transistor (22) is electrically connected to the other end of the digital-to-analog converter module (24).

5. The dynamic arc suppression device of the transformer DC resistance tester according to claim 1, characterized in that: The acquisition circuit includes a current sensor (31), a voltage sensor (32), and a current and voltage acquisition module (33); the first end of the voltage sensor (32) is electrically connected to the A end of the transformer winding (13) under test, the second end is electrically connected to the B end of the transformer winding (13) under test, and the third end is electrically connected to the first end of the current and voltage acquisition module (33); the first end of the current sensor (31) is electrically connected to the resistor (23), the second end is electrically connected to the negative terminal of the DC circuit (11), and the third end is electrically connected to the second end of the current and voltage acquisition module (33); the third end of the current and voltage acquisition module is electrically connected to the microcontroller (25).

6. The dynamic arc suppression device of the transformer DC resistance tester according to claim 2, characterized in that: The air switch (12) is electrically connected to the main circuit and connected in series with the DC circuit (11).

7. The dynamic arc suppression device of the transformer DC resistance tester according to claim 5, characterized in that: The voltage sensor (32) is connected in parallel with the winding (13) of the transformer under test.

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