CN109326485B

CN109326485B - Arc extinguish chamber contact structure and method for determining transient voltage waveform of synthetic test loop

Info

Publication number: CN109326485B
Application number: CN201811070284.6A
Authority: CN
Inventors: 翟小社; 姚晓飞
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2018-09-13
Filing date: 2018-09-13
Publication date: 2020-03-17
Anticipated expiration: 2038-09-13
Also published as: CN109326485A

Abstract

The invention discloses an arc extinguish chamber contact structure and a method for determining the transient voltage waveform of a synthetic test loop, wherein the arc extinguish chamber contact structure comprises a first contact and a second contact, a groove is formed in the upper surface of the first contact, a conical discharge structure is arranged in the middle of the bottom of the groove, the upper surface of the first contact is attached to the lower surface of the second contact, a gap is formed between the top of the conical discharge structure and the lower surface of the second contact, the contact structure and the method can effectively reduce the interception level of a vacuum arc extinguish chamber, and the TRV detection result is accurate.

Description

Arc extinguish chamber contact structure and method for determining transient voltage waveform of synthetic test loop

Technical Field

The invention belongs to the technical field of high-capacity tests of circuit breakers, and relates to an arc extinguish chamber contact structure and a method for determining a transient voltage waveform of a synthetic test loop.

Background

In the synthetic test of the circuit breaker, because the circuit breaker is in the initial stage of the thermal recovery of the arc extinguish chamber in the time window of the action of the Transient Recovery Voltage (TRV), compared with the stage of the recovery voltage of the power frequency, the waveform parameters in the TRV stage have larger influence on the short circuit breaking process of the circuit breaker, and therefore, before the new test loop or the new loop parameters are applied to the test, whether the TRV meets the requirements of GB1984-2003 and IEC62271-100 and 2008 or not must be checked.

When the test circuit breaker is used for TRV waveform detection by a direct short-circuit breaking method, due to the influence of the characteristics of the circuit breaker, under the action of different arc voltages, arc currents and cut-off levels, the detection results of the TRV have larger difference, so that when the vacuum circuit breaker with lower arc voltage is used for test detection, the cut-off level of a vacuum arc extinguish chamber is further reduced, and the method is a key technology for realizing ideal zero-crossing breaking of the circuit breaker and obtaining the expected waveform of a standard TRV.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides an arc extinguish chamber contact structure and a method for determining the transient voltage waveform of a synthetic test loop.

In order to achieve the purpose, the vacuum arc extinguish chamber contact structure for TRV detection comprises a first contact and a second contact, wherein a groove is formed in the upper surface of the first contact, a conical discharge structure is arranged in the middle of the bottom of the groove, the upper surface of the first contact is attached to the lower surface of the second contact, and a gap is formed between the top of the conical discharge structure and the lower surface of the second contact.

The inner wall of the groove is of a smooth structure.

The cross section bilateral symmetry of recess and toper discharge structure component part, wherein, the shape of left side part comprises first pitch arc, slash segment, second arc, horizontal line segment, third pitch arc and fourth arc, and wherein, the slash segment is tangent with first arc and second arc, and horizontal line segment is tangent with second pitch arc and third arc, and the fourth pitch arc is tangent with the upper surface of third arc and first contact.

The distance between the top of the conical discharge structure and the lower surface of the second contact is 0.5mm, and the taper of the conical discharge structure is 45-135 degrees.

The lower surface of the second contact is of a planar structure.

The method for determining the transient voltage waveform of the synthetic test loop comprises the following steps: when a TRV expected waveform test is carried out, based on phase selection and closing control of a test generator or a short-circuit transformer, the contact structure of the vacuum arc-extinguishing chamber for TRV detection is broken in a test current half-wave, so that in an arc burning half-wave in the breaking process, a first contact is a cathode of arc voltage, a second contact is an anode of the arc voltage, and at the moment, in the process that alternating current arc current approaches zero, due to the fact that the cathode electron emission capability of the first contact is strong, current for maintaining arc gap conduction is continuously provided through the first contact, and sudden cut-off before the alternating current zero passage is avoided.

When the current is extinguished, the TRV voltage is reversely applied to the contact structure of the vacuum arc-extinguishing chamber for TRV detection, the first contact is used as an anode of the arc voltage, the second contact is used as a cathode of the arc voltage, and the second contact is weaker in electron emission capability in an on-off period, so that the insulation impedance between the first contact and the second contact is increased, and a high impedance condition is provided for the TRV test.

The invention has the following beneficial effects:

when the arc extinguish chamber contact structure and the method for determining the transient voltage waveform of the synthetic test loop are used for carrying out TRV expected waveform test, the first contact is the cathode of the arc voltage, the second contact is the anode of the arc voltage, and at the moment, in the process that the alternating current arc current approaches zero, because the cathode electron emission capability of the first contact is strong, the first contact continuously provides the maintaining arc gap conducting current, the sudden cut-off before the alternating current zero passage is avoided, and the ideal cut-off of the current zero passage is realized; after the current is extinguished, in the on-off period, the first contact is used as an anode of the arc voltage, the second contact is used as a cathode of the arc voltage, and the second contact is weaker in electron emission capability, so that the insulation resistance between the first contact and the second contact is increased, a high-impedance condition is provided for the TRV test, and the accuracy of the TRV detection result is effectively improved.

Drawings

Fig. 1 is a schematic view of the structural parameters of a first contact 1 according to the invention;

FIG. 2 is an enlarged view at B in FIG. 1;

FIG. 3 is a schematic structural view of the present invention;

FIG. 4 is a graph showing an electric field distribution at a TRV peak voltage of 22.0kV with a contact pitch of 10 mm.

Wherein, 1 is a first contact, 2 is a second contact, and 3 is a conical discharge structure.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings:

the vacuum circuit breaker cut-off phenomenon is caused by that in the process of that the alternating current arc current is approaching to zero, the shrinkage joule heat of arc cathode and the bombardment energy of positive ion to cathode are reduced, so that the metal evaporation quantity of cathode surface is reduced, and the quantity of inter-electrode steam particles and conductive particles is reduced, at the same time, because the particles under the vacuum environment are quickly diffused, when the inter-electrode conductive particles are not enough to maintain the arc combustion at a certain moment, the current is suddenly cut off.

Referring to fig. 3, the contact structure of the vacuum interrupter for TRV detection according to the present invention includes a first contact 1 and a second contact 2, wherein a groove is disposed on an upper surface of the first contact 1, a conical discharge structure 3 is disposed at a middle position of a bottom of the groove, the upper surface of the first contact 1 is attached to a lower surface of the second contact 2, and a gap is formed between a top of the conical discharge structure 3 and the lower surface of the second contact 2; the lower surface of the second contact 2 is of a planar structure.

The inner wall of recess is smooth structure, and wherein, the cross section bilateral symmetry of recess and toper discharge structure 3 component part, wherein, the shape of left side part comprises first pitch arc, slash segment, second arc, horizontal line segment, third pitch arc and fourth arc, and wherein, the slash segment is tangent with first arc and second arc, and horizontal line segment is tangent with second pitch arc and third arc, and the fourth pitch arc is tangent with third arc and first contact 1's upper surface.

The method for determining the transient voltage waveform of the synthetic test loop comprises the following steps: when a TRV expected waveform test is carried out, based on phase selection and closing control of a test generator or a short-circuit transformer, the contact structure of the vacuum arc-extinguishing chamber for TRV detection is broken in a test current half-wave, so that in an arc burning half-wave in the breaking process, the first contact 1 is a cathode of arc voltage, the second contact 2 is an anode of the arc voltage, and at the moment, in the process that alternating current arc current approaches zero, because the cathode electron emission capability of the first contact 1 is strong, current for maintaining arc gap conduction is continuously provided through the first contact 1, and sudden cut-off before the alternating current zero passage is avoided.

When the current is extinguished, the TRV voltage is reversely applied to the contact structure of the vacuum arc-extinguishing chamber for TRV detection, in the open-close period, the first contact 1 serves as an anode of the arc voltage, the second contact 2 serves as a cathode of the arc voltage, and the second contact 2 has a weak electron emission capability, so that the insulation impedance between the first contact 1 and the second contact 2 is increased, thereby providing a high impedance condition for the TRV test.

Example one

Referring to fig. 1 and 2, typical parameters of a 10kV vacuum arc-extinguishing chamber are adopted, the opening distance is 9-10 mm, the diameters of the first contact 1 and the second contact 2 are 42mm, the short circuit breaking capacity can reach 31.5kA, the distance between the conical discharge structure 3 and the second contact 2 is 0.5mm, the taper of the conical discharge structure 3 is kept between 45-135 °, and fig. 2 shows the structural size of the first contact 1.

Fig. 4 shows the electric field distribution when the contact pitch is 10mm and the TRV peak voltage is 22.0kV, and it can be seen from fig. 4 that the electric field intensity at the tip of the conical discharge structure 3 is much greater than other parts in the field, and the arc gap maintaining current can be continuously provided when the alternating current arc current approaches zero, so as to avoid sudden cutoff before the current zero-crossing.

Claims

1. A method for determining the transient voltage waveform of a synthetic test loop is characterized in that the method is based on a vacuum arc-extinguishing chamber contact structure for transient recovery voltage detection, the vacuum arc-extinguishing chamber contact structure for transient recovery voltage detection comprises a first contact (1) and a second contact (2), wherein a groove is formed in the upper surface of the first contact (1), a conical discharge structure (3) is arranged in the middle of the bottom of the groove, the upper surface of the first contact (1) is attached to the lower surface of the second contact (2), and a gap is formed between the top of the conical discharge structure (3) and the lower surface of the second contact (2);

the method comprises the following steps: when the expected waveform test of the transient recovery voltage is carried out, based on phase selection and closing control of a test generator or a short-circuit transformer, a vacuum arc-extinguishing chamber contact structure for detecting the transient recovery voltage is divided in a test current half-wave, so that in an arc half-wave in the dividing process, a first contact (1) is a cathode of an arc voltage, a second contact (2) is an anode of the arc voltage, and at the moment, in the process that the alternating current arc current approaches zero, because the cathode electron emission capability of the first contact (1) is strong, the first contact (1) continuously provides current for maintaining arc gap conduction, and the alternating current arc current is prevented from being suddenly cut off before zero crossing;

after the current is extinguished, the transient recovery voltage is reversely applied to a contact structure of a vacuum arc extinguish chamber for detecting the transient recovery voltage, in the on-off period, the first contact (1) is used as an anode of the arc voltage, the second contact (2) is used as a cathode of the arc voltage, and the electron emission capability of the second contact (2) is weaker, so that the insulation impedance between the first contact (1) and the second contact (2) is increased, and a high impedance condition is provided for testing the transient recovery voltage.

2. The method for determining a synthetic test loop transient voltage waveform of claim 1, wherein an inner wall of the recess is smooth.

3. The method for determining a composite test loop transient voltage waveform of claim 2, wherein the distance between the top of the conical discharge structure (3) and the lower surface of the second contact (2) is 0.5mm, and the taper of the conical discharge structure (3) is 45 ° to 135 °.

4. The method for determining a composite test loop transient voltage waveform of claim 2, wherein the lower surface of the second contact (2) is of planar configuration.