A bellows (a in Fig. 1) is welded to the static end of the vacuum interrupter to connect the arc chamber. When the arc-extinguishing chamber manufacturer pulls vacuum on the exhaust table, the bellows is in a compressed state. After the arc extinguish chamber is sealed off, a pressure spring is added to the periphery of the corrugated pipe at the static end of the arc extinguish chamber during installation and use (Fig. l b).
Under normal conditions, the self-closing force of the bellows of the arc-extinguishing chamber is balanced with the reaction force of the compression spring, and the bellows is basically in a compressed state. When the degree of vacuum in the arc chamber drops, the self-closing force decreases. When the vacuum degree drops below 10-lZPa, the bellows of the static end tends to extend under the action of the spring reaction force, and the axial displacement of the static end of the arc extinguishing chamber occurs, and the displacement thereof corresponds to the change of the vacuum degree in the arc extinguishing chamber. The indicator is driven by the displacement sensor (middle c) or the digital display; when a sudden air leak occurs, an audible and visual alarm signal is immediately sent out and the switch is locked.
Test Results and Analysis Hand Span Spring Bellows Thermocouple Gauge Vacuum Gauge Vacuum Fire Arc Ion Gauge Pipeline Connection to Evacuator Vacuum In-line Inspection Technology Test System Diagram To verify the feasibility of the vacuum degree on-line inspection system, a simulation was made Detection system, as shown. A vacuum interrupter sample (with a static bellows and an auxiliary spring) with a thermocouple regulator and an ionization gauge tube is evacuated according to normal exhaust conditions. The oil diffusion pump is turned off when the vacuum level reaches 5xlo to 4Pa. Natural cooling.
When the vacuum degree drops to 10 to Zpa, the gas is slowly flushed into the arc-extinguishing chamber, and the degree of vacuum and the change of the meter are observed. After repeated trials, it is known that when the vacuum degree in the vacuum interrupter is reduced to 10-1, the detection device can monitor and indicate when the vacuum is lower than the Pa. With the continuous decrease of the vacuum degree, the indicating sensitivity is continuously improved, and the repeatability is good. When the vacuum level drops below 0.SPa, it can be clearly indicated.
When the sudden air leakage occurs, the bellows elongation suddenly increases by 4 to 6 m. Description: The sensitiveness of the detection device is related to the structural parameters of the bellows and the pressure spring. After many tests, the best matching parameters have been determined. Indicators can be used with hands and displacement sensors (converted to digital display) in order to test the application of the techniques described in the actual vacuum switch. We will use this technology's special vacuum interrupter to assemble a ZN28AG-10/1250 indoor high-voltage vacuum circuit breaker.
Sealing vacuum degrees of the three arc chambers were respectively 0.85pa, o.sopa, and o.95pa. The product was subjected to a breaking test of 30%, 60%, and a short-circuit rated current (31.5 kA). The results show that 30%, 60%, and 10% of each break once, are normal, power frequency withstand pressure 42kv/lmin pass; when a further 100% cut off also passed. After zomin was applied at 42kv/lmin, the phases A and B were normal, and the C-phase interrupter flashed twice.
After parking for 2 hours, the voltage of A and B phase lmin power frequency can be added to 48kv, and the c phase 1.6kv, flicker occurs in the tube. Tests show that when the vacuum switch vacuum degree is above 10Pa, it can still work normally, but it should be considered that it is in a critical state of reliable operation. Application example We will be in accordance with the normal process of vacuum interrupter containing vacuum degree detection technology assembly into a zN28AG-1011250 a 31. Indoor high voltage vacuum circuit breaker installed in the factory production xoNIG a 021250 a 31. vacuum cabinet cabinet In China, the products passed the type test of breaking, insulation, and dynamic heat stability at the high voltage switch test station of China Electric Power Research Institute.
The technology (product zN28Ae-1021250-31.5 indoor high-voltage vacuum circuit breaker) was approved by the Ministry of Industry Administration of the State Administration of Machinery Industry and the Ministry of State Security Organization of Security Operations and Transmission and Distribution Department on January 23, 199. .
The appraisal considers that: 1) The vacuum switch vacuum degree on-line detection technology developed by Zhenjiang Electrical Equipment Factory (sample is installed in the zN28AG-10/1250-31.5 series indoor high-voltage vacuum circuit breaker) uses the principle of balance between bellows and spring pressure, To make the vacuum pressure cause a change in the self-closing force, a micrometer can be used to indicate a slight vacuum pressure increase. When a serious air leak occurs, a glow alarm can be issued and the circuit breaker can be locked.
2) After the product has undergone a full-scale type test, its technical indicators have reached the requirements specified in GB1984 "AC High-Voltage Circuit Breakers" and product specifications. The product has been tested by users for more than a year and is in good condition. 3) The product's process, tooling, testing methods and factory production conditions meet the needs of mass production. The ZN28(A)G series vacuum circuit breakers produced by this technology have been serialized. Since the appraisal, the cumulative production and sales of more than 200 units have been well received by users.
The plant has also applied this technology to floor-standing, mid-mounted vacuum circuit breakers and it is being tested and extended to vacuum contactors and vacuum load switches. Gratifying progress has been made. ZN28G-12 (including vacuum degree on-line detection) outline drawing Huwei giant such as N28AG-12 (including vacuum degree on-line detection) shape conclusion Vacuum switch vacuum degree online detection technology is an important aspect of the intelligent technology of switchgear, is the vast number of users The important issues of concern and hope for practical products, the technical principles discussed in this article are clear and practical.
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