HV insulation

Oil bushings are adjustable capacity bushings manufactured with resin impregnated paper (RIP) or resin impregnated synthetic (RIS) insulation. They are intended for use in power transformers to connect two oil media in accordance with the IEC 60137-2017 standard.

The design, components and production technology of the bushings guarantee an average service life of 30 years under normal operating conditions. They offer advantages over conventional bushings (oil, gas), mainly in terms of safety, environmental protection and maintenance-free operation.

RIS technology

Resin-impregnated synthetics (RIS) are the latest technology in the high-voltage bushing industry (in the case of ChinSun, we have over 10 years of manufacturing experience). An increasing number of power projects require paperless bushings to ensure outstanding transformer performance. Yes, this is the current trend in the HV bushing market, which actually shares many similar points with resin impregnated paper (RIP) technology. But while RIS shares many similar properties compared to resin-impregnated paper (RIP) technology, RIS really excels in the following aspects:

• The RIS bushing does not contain hygroscopic material, such as the paper used, making it easier to store.
• Partial discharge to double voltage between phase and earth.
• Fully dry passage, no oil leakage, no risk of explosion
• Shipment time is faster than for RIP bushings because resin impregnation time is reduced
• No maintenance required

ChinSun® RIS bushing technology is one of ChinSun’s national patents. So ChinSun, as the original innovator of this type of RIS bushings, is a strong competitor in terms of technique and price.

Introduction of filling paste for porcelain penetrations

ChinSun uses a special filling paste between the inner and outer insulation gap of the bushing.
The filling paste is a kind of insulating polymer, a high molecular weight white polymer with a high viscosity index, insoluble in water and non-flowing.

It is characterized by resistance to changing weather conditions, cold, moisture, acids, alkalis, exemplary tightness, volume resistivity, high insulation breakdown voltage, very good dielectric loss coefficient, low expansion coefficient and high thermal stability. The insulating polymer does not contain metal ions or other harmful substances.

It is a special material for filling the gap space of high voltage bushing, which has good compatibility with the inner capacitive core and outer porcelain casing. After filling with paste, the bushing is well protected against moisture, water and insulation expansion or contraction, so we can solve the problems of leakage and protection of the bushing under various environmental and climatic conditions to ensure the stability and reliability of operation.

This guarantees the safe use of sleeve bushings in various environments, even in difficult weather conditions.

According to what standard is the ChinSun® bushing manufactured and tested?

The ChinSun® bushing not only meets all specifications required by IEC 60137, but also the electrical, thermal and mechanical properties of the relevant IEEE standards. ChinSun bushings feature a very low dielectric loss factor tanδ typically < 0.35%, while the bushings' electrical design and void-free impregnation process ensured they are resistant to partial discharges up to twice the maximum phase-to-ground operating voltage, determined by the background noise of the partial discharge measurement amounting to 2 pC. These data are significantly better than those specified in the IEC standard for RIP bushings, i.e. dielectric losses <0.7%, partial discharge levels <10 pC and <5 pC at 1.5 and 1.05 times the maximum phase operating voltage respectively -earth.