Ester Insulation Fluid — Transformer Glossary

Biodegradable insulation fluid with superior fire safety properties, available as natural ester (plant-based) or synthetic ester.

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Ester Insulation Fluid

Biodegradable insulation fluid with superior fire safety properties, available as natural ester (plant-based) or synthetic ester.

Natural ester (e.g., FR3™ by Cargill): fire point 360°C, biodegradable, extends paper insulation life 5–8× by actively absorbing moisture from cellulose. Pour point -21°C. Synthetic ester (e.g., MIDEL 7131): fire point 316°C, pour point -56°C (ideal for extreme cold), better oxidation stability than natural ester. Both types are K-class fluids under IEC 61099. Retrofilling — converting existing mineral oil transformers to ester — is increasingly popular for fire safety and environmental compliance in urban and indoor installations.

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transformersOil & Gas TransformersSpecialized transformers for hazardous and explosive environments in oil, gas, and petrochemical industries.

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KNAN (Ester Natural Air Natural)Cooling method using natural or synthetic ester fluid instead of mineral oil, with natural convection cooling. The 'K' designates ester fluid per IEC naming conventions.

Insulation ClassClassification of insulation materials based on their maximum continuous operating temperature. Determines the transformer's thermal endurance.