Tambayar da Dalilin Farkon Tashar Ziyartar da Kirkiyar Amfani na Gwamnatiyar Kirkiyar Jiragen Vakuma a Koyar Yakin Da Take Cika Vakuma

Akwai amfani da kisan tushen vacuum circuit breakers a cikin network na distribution. A matsayin mafi girman wurare da ke tsara wannan wurar, kyauke da shi yana nuna kan abubuwa da suka samu daga vacuum interrupters da kuma kayan aiki masu mechanical na circuit breakers (distance da ake bude da ita, stroke, pressure, average closing/opening speed, closing bounce time, opening - closing asynchronism, operation times, and cumulative allowable wear of contacts). Duka suna da muhimmanci wajen aiki da inganci. An san vacuum interrupter da "kalbinta" na circuit breaker; ba a zama na bi da inganci da kyau, ba za a iya samun aiki da inganci ba. Saboda haka, ya kamata a yi rawa da yanayin kimi da kula da kudin aiki ga interrupters, tun daga kula da kudin aiki na performance, don samun aiki da dalilai da kalmomi.

1 Muhimman Indakunan Vacuum Interrupters

Kisan tushen vacuum interrupter an samu daga system na insulation mai tsabta (enclosure), system na conductive, da kuma system na shielding. Kyaukarsu yana nuna kan level na insulation (1-min power-frequency withstand voltage, 1.2/50 impulse withstand voltage), degree na vacuum, da kuma resistance na DC na main-circuit. Don samun kula da kudin aiki da kula da kudin bayyana, ya kamata a yi testing da analysis na duka waɗannan indakuna.

An amfani da rikitar power-frequency withstand voltage na musamman don yanayin insulation a gida. Amma saboda siffar teknologi na testing, an yi amfani da testing na degree na vacuum zuwa yanzu. Amma, a wasu yankunan, "Regulations for Handover and Preventive Tests of Electrical Equipment" ba su tabbas ba su fiye da testing na degree na vacuum, kuma suke sufi "using fracture withstand voltage as a substitute when detection is unfeasible". Wannan yana haifar da fahimtata da kula da kudin aiki, kuma yana iya haifar da kashe da kwallon aiki. Ina tambaya a yi kawoƙar da al'amuran da za su iya taimaka wajen zama da system na bayyana na performance na interrupters da kuma zama da aiki da dalilai da kalmomi a wurare na distribution.

1.2 Turukan Noma da Vacuum Interrupters

A nan da na yi yanayin a gida, an samu cewa noma da vacuum interrupters suna da duhu:

• Noma da ma'anar da suka haifar da shell rupture ko bellows damage, wanda ke haifar da entry da air, loss of vacuum a interrupter, da kuma communication da atmosphere.

• Noma da ma'anar da suka haifar da gradual decrease of vacuum degree. Ba sai interrupter ya zama na communication da atmosphere, amma pressure na air na gida ta yi karfin da take daɗe saboda manufacturing processes, transportation, installation, ko maintenance factors, wanda ke haifar da interrupter ba ta iya samun breaking capacity na normal. Dalilan noma da ma'anar da suka haifar da danger da ya fi yawa da noma da ma'anar. Decrease in vacuum degree zai iya haifar da overcurrent breaking capability na vacuum circuit breaker, zai iya shararren service life na circuit breaker, da kuma zai iya haifar da switch explosion a halayen ci gaba.

1.3 Tabbatar da Limitations na Power Frequency Withstand Voltage da Testing na Vacuum Degree

Daga perspective na on-site practical experience:

• Rikitar power frequency withstand voltage test yana da darasi da yake daidaita da noma da ma'anar, kuma zai iya qualitative determine status na interrupter. Amma, yana da blind spot don noma da ma'anar: idan degree na vacuum yana cikin range na 1×10⁻²Pa to 1×10⁻³Pa, rikitar power frequency withstand voltage test zai iya pass. A lokacin, degree na vacuum ta zama lafiya da 1.66×10⁻²Pa, kuma subtle differences ba su iya daidaita ba.

• Tester na vacuum degree zai iya accurate measurement a cikin range na 1×10⁻¹Pa to 1×10⁻⁵Pa, wanda ke upgrade testing na interrupters daga qualitative analysis zuwa quantitative stage. Zai iya deduce service life na vacuum interrupter based on change na vacuum degree over a certain period, wanda ke provide technical support for equipment reliability evaluation. Amma, wannan method yana da limitations a cikin range na testing: idan ta yi karfe 1×10⁻¹Pa to 1×10⁻⁵Pa, proportional relationship between ion current and residual gas density (i.e., vacuum degree) wanda tester na vacuum degree ke amfani da shi zai canzawa, kuma accuracy na results ba za su daɗe ba. Masu ma'anar da suka haifar da leakage complete (communication da atmosphere), test values zai iya zama close da normal state, wanda ke iya haifar da misjudgment. Dalilin da ake amfani da shi ita ce gas collision theory: idan gas pressure ta yi karfe, molecular density ta yi karfe, wanda ke haifar da mean free path na electrons ta yi haka. Idan number of collisions ta yi karfe, insufficient kinetic energy accumulation na electrons zai iya reduce probability of gas molecule ionization, wanda ke haifar da instrument ya misjudge vacuum degree as good.

Based on on-site detection practice, it should be particularly noted that the power frequency withstand voltage test cannot be omitted during detection. Only when the interrupter passes the power frequency withstand voltage test can it be ensured that the vacuum degree is within the effective range of the tester, and the subsequent vacuum degree test results can be reliable. Therefore, the vacuum degree test and the power frequency withstand voltage test must be applied in combination. The two methods complement each other, and relying solely on either method to judge the status of the interrupter has limitations.

1.4 Main Circuit Resistance Test

A nan da na yi yanayin a gida, an amfani da DC voltage drop method don main circuit resistance testing, using a tester with a current of not less than 100A. Resistance values after handover and overhaul shall comply with the manufacturer's regulations, and during operation, they shall not exceed 1.2 times the factory value. When the contact wear of the vacuum interrupter causes poor contact, problems can be detected through circuit resistance testing. If the main circuit resistance is unqualified for a long time, it may cause the interrupter to overheat, leading to a decline in the insulation performance of related components and even short-circuit explosions.

2 Measures to Improve Vacuum Interrupter Reliability

• Regularly carry out vacuum degree testing (combined with 42kV power frequency withstand voltage test) to judge the interrupter status. When the vacuum degree decreases, the vacuum bubble must be replaced (most products require replacing three phases simultaneously if one phase is unqualified), and characteristic tests such as stroke, synchronism, and bounce shall be completed.

• Formulate detection cycles based on the preventive test regulations for electrical equipment and the unit's actual conditions. Increase monitoring frequency in the first two years after commissioning; it is recommended to conduct power frequency withstand voltage and vacuum degree tests at half a year, 1 year, 1.5 years, and 2 years after commissioning, then adjust the frequency according to operation conditions after 2 years.

• Reasonably plan maintenance cycles and inspect interrupters combined with annual preventive tests. After 2,000 normal operations or 10 rated current interruptions, check all parts and parameters; if bolts are not loose and technical parameters meet standards, continue using.

• Regularly test the contact resistance between the two ends of the interrupter and main circuit terminals to ensure it does not exceed the specified value.

• When conditions permit, perform infrared imaging temperature measurement on the conductive circuit through the observation hole to track temperature trends. Unqualified main circuit resistance, poor contact, insulation defects, or insufficient heat dissipation gradient due to unreasonable interrupter design can all cause temperature rise in conductive and insulating components, leading to accidents.

• Operation personnel shall regularly patrol the circuit breaker and pay attention to whether there is discharge outside the vacuum bubble (discharge usually indicates unqualified vacuum degree testing, requiring timely power outage for replacement). Maintenance key points:

• Check appearance and wipe dirt

• Replace the vacuum tube if the cumulative wear thickness of moving and static contacts exceeds 3mm

• Regularly inspect and adjust contact opening distance, compression stroke, and three-phase synchronism

3 Conclusions

• The power frequency withstand voltage, vacuum degree, and main circuit DC resistance of the vacuum interrupter are important indicators for characterizing its performance, playing a key role in mastering leakage trends and estimating service life.

• Vacuum degree testing and power frequency withstand voltage test each have limitations and need to be applied in combination to accurately diagnose interrupter reliability.

• The two tests cannot replace each other; interrupters failing the tests must be replaced, and it is recommended to revise relevant industry test regulations in a timely manner.

• Improving reliability should start with regular vacuum degree, power frequency withstand voltage, and main circuit resistance tests, strengthen technical training for operation and maintenance personnel, conduct careful patrols, infrared temperature measurement, and scientific detection-maintenance cycle planning to avoid explosions and other accidents caused by non-electrical misoperations during circuit breaker operation or load switching.