Shell Diala S4 ZX-IG
Shell Diala S4 ZX-IG is a premium inhibited electrical insulating oil developed to provide high performance dielectric insulation and extended operational life in electrical transformers and specialised high voltage equipment. The oil is manufactured using Shell’s advanced gas-to-liquid (GTL) base oil technology, delivering highly consistent base fluid composition, excellent oxidation resistance and reliable long-term performance in demanding electrical systems.
A key advantage of Shell Diala S4 ZX-IG is its exceptional oxidation stability. The oil meets the requirements of IEC 60296 for higher oxidation stability and low sulphur content, as well as the performance of ASTM D3487 Type II transformer oils. Its fully inhibited formulation helps resist degradation during prolonged service, enabling extended oil life and reducing maintenance requirements in electrical equipment.
Shell Diala S4 ZX-IG is specifically engineered to provide reliable gas absorption performance. The oil has the ability to absorb gases such as hydrogen that can form during partial discharge events within high voltage systems. This makes it particularly suitable for specialised equipment such as instrument transformers and high voltage bushings, where gas absorption capability is critical for operational stability and safety.
The formulation also provides excellent transformer protection. The oil is produced from zero-sulphur base oils with sulphur content below the detection limit of ASTM D5185, making it intrinsically non-corrosive to copper components without requiring passivating additives. It meets multiple copper corrosion test standards including DIN 51353, ASTM D1275, IEC 62535 and ASTM D1275B, ensuring reliable protection of internal transformer components.
System efficiency is supported by strong thermal and fluid flow characteristics. The oil’s low temperature viscometric properties enable effective heat transfer within transformers even during low temperature start-up conditions. It is specially dried and carefully handled to maintain very low water content and high dielectric breakdown strength at delivery, allowing it to be used in many applications without additional treatment.
Shell Diala S4 ZX-IG is also biodegradable according to OECD 301B testing, achieving more than 60% biodegradation after 28 days. This characteristic supports environmentally responsible transformer operation while maintaining the high performance required for critical electrical equipment.
Typical physical characteristics include density of approximately 806 kg/m³ at 20°C, viscosity of 9.4 mm²/s at 40°C and 2.7 mm²/s at 100°C, flash point of 158°C and pour point of –42°C. The oil provides high dielectric strength, with untreated breakdown voltage around 59 kV and approximately 75 kV after treatment. Dielectric dissipation factor values remain extremely low, supporting efficient insulation performance.
Shell Diala S4 ZX-IG is recommended for power transformers, high voltage bushings and instrument transformers requiring gas absorbing insulating oils with high oxidation stability and long operational life. It is free from PCBs, DBDS and passivators and contains only DBPC antioxidant along with a low aromatic hydrocarbon content to support gas absorption behaviour.
