Rûgîn-Voltage Nîçvekî û Temsîlwarên RMUs: Têkerdina Epoxy Resin û Rêzeyê Cihanebaza Dîtin

1 Bêşî û Pencereyên Şîl

Berdî statîstîkên biha ji bo unitên sîkorî yên însûlatandîn bîsînî yên nîvîn-bihî (RMUs), pencereya şîlê dike nav 40% ji biha gjîr. Demekî, çemkirdina bêşîyan ên rêzik, çemkirina pencereyên şîl ên rastîn, û çemkirdina rêzikên şîl ên serast hene wan derbasên pir dike nav biha RMUs yên nîvîn-bihî. Ji ber hejmaran da ku epoxy resin hatiye pêvekirin di salê 1930 de, çendîn additîfên din hatiye dargir kirin da ku propertîyên wî biguherînin.

Epoxy resin li gor dikareya şîlê ya bikar, guharta mekanîkîya bikar, guharta cîzekirîna minimalkirî di dema casting û curing de, û asanîna machining hatiye hilbijartin da ku bêşîya şîl ên serast bibe ji bo RMUs yên nîvîn-bihî. Bi zêdekirina hardeners, tougheners, plasticizers, fillers, û colorants, epoxy resin ên bikarhatî hatiye formkirin. Dikareya garmî, garmî dilavzandî, û garmî dilavdarî wê hatiye guhertin, da ku flam retardancy û performansa şîl ên yekbûn di şertên voltage û overvoltage derdîn de were destnîşan.

Di RMUs de, pencereyên şîl ên taybet hatiye dewletandina elektrîkî yên ne-uniform. Di vê dewletandinan de, tenê zêdekirina distanca şîlê tune ye ku bibe şîl ên bikar. Demekî, uniformity ya dewletandina elektrîkî da ku bibe çemkirin dike nav optimizekirina pencereyê. Dikareya şîlê ya epoxy resin dike nav 22-28 kV/mm, ma'niya ku, bi pencereya şîl ên optimizekirin, tenê qate millimeteran distanca şîlê diben bibin di navên phase an, ku herî bi guherta minimalkirîna mezatên pirêza.

2 Pencereyên Structur û Design ûn Medium-Voltage Solid-Insulated RMUs

Hemî komponentên conductive—wisa vacuum interrupters, disconnect switches, û grounding switches—di mold de hatiye nivîsand û integrally cast bi karîna epoxy resin ên bikarhatî bi Automatic Pressure Gelation (APG) process. Mediuma arc extinguishing vacuum e, ji ber ku insulation dike nav epoxy resin ên bikarhatî. Cabinet modular design dike nav adopt kirin, ku bihêvişîn standardization mass production. Her kompartment dike nav separate bi metal partitions da ku bibe prevent arc propagation, ku potential faults dike nav confine nav individual modules.

Integrated busbar û contact connectors hatiye design kirin. Main busbar dike nav consist nav segmented, insulated enclosed busbars connected via telescopic integrated busbar connectors, simplifying on-site installation û commissioning. Door structure dike nav design da ku bibe withstand internal arcing û allows three-position operations (closing, opening, û grounding) with the door closed. Switch position status dike nav easily observed through viewing windows, ensuring safe û reliable operation.

3 Advantages û Type Test Analysis ûn Medium-Voltage Solid-Insulated RMUs
3.1 Main Advantages

• Epoxy resin ên bikarhatî dike nav ensure reliable insulation performance û low partial discharge (≤5 pC).

• Fully insulated û sealed structure dike nav no exposed live parts, making it immune to dust û contamination. It is not limited by environmental conditions û is suitable for high/low temperatures, plateaus, explosion-proof areas, û polluted regions. It solves issues related to SF₆ gas pressure changes at high temperatures û gas liquefaction at low temperatures. For example, Fuzhou, located in a coastal high-salt-fog area, benefits significantly from the product's salt-fog resistance.

• No SF₆ gas dike nav use; no harmful gases dike nav emit, making it an environmentally friendly product. There is no risk of leakage, eliminating the need for regular maintenance—making it maintenance-free. Enhanced explosion-proof design ensures suitability for hazardous locations. The fully insulated three-phase structure prevents phase-to-phase short circuits, ensuring safety û reliability.

• The equipment occupies only 30% of the space required by conventional air-insulated RMUs, making it an ultra-compact product.

3.2 Type Test Analysis

In line with the above advantages, corresponding type tests were conducted, including insulation withstand voltage tests (42 kV/48 kV), partial discharge measurement (≤5 pC), high/low temperature tests (+80 °C / -45 °C), condensation tests (Pollution Level II), and internal arc tests (0.5 s). Test results confirm full compliance with parameter requirements, effectively validating the product's stated advantages.

Additionally, other type tests required by national standards were completed: temperature rise test, main circuit resistance measurement, rated peak and short-time withstand current tests, rated short-circuit making and breaking capacity tests, electrical endurance, mechanical endurance, fault tests under phase-to-phase grounding, rated active load current switching tests, and rated capacitive current switching tests. All test results meet national standard requirements.

State Grid Corporation of China has held multiple meetings to discuss the type test items and parameter requirements for medium-voltage solid-insulated RMUs, with in-depth discussions on specific details such as whether the partial discharge limit should be ≤5 pC or ≤20 pC. We believe that the type tests mandated by national standards are essential and must be performed; additional tests conducted to verify product advantages are also necessary; furthermore, special tests such as vibration and severe climate condition tests should be selected based on the actual operating environment. Regarding parameters, while State Grid sets only baseline requirements, manufacturers can appropriately enhance specifications according to product performance—for instance, raising the partial discharge limit to ≤5 pC and extending the temperature range for high/low temperature tests.

4 Conclusion

Solid insulation offers significant advantages over gas and air insulation: reliable insulation performance, no harmful gas emissions, environmental friendliness, and no leakage issues. The application of solid insulation technology has greatly enhanced the miniaturization and environmental adaptability of medium-voltage RMUs, enabling wide application in high/low temperatures, plateaus, explosion-proof areas, and polluted regions. All these advantages have been fully validated through type testing.