The document discusses replacing mineral oil with synthetic ester fluids in transformers to improve fire safety, moisture tolerance, and environmental performance. Some key benefits of retrofilling transformers with MIDEL 7131 ester fluid include significantly higher fire points which increase safety, moisture tolerance which reduces maintenance needs, and faster biodegradation providing greater environmental protection. Case studies on retrofilling projects in Sharjah, Berlin, and Devonport found the ester fluid improved insulation resistance and moisture content while increasing breakdown voltage.

1. Retrofilling with Ester Based Transformer Dielectric Fluid to Improve Fire Safety, Moisture Tolerance and Environmental Behaviour March 2011 Copyright 2011 M&I Materials Ltd. Products of M&I Materials Ltd.

2. Transformer Fluids Introduction Poor Excellent Poor Moisture Tolerance No Yes No Fully Biodegradable >350°C 316°C 170°C Typical Fire point Synthetic Product Synthetic Product Crude Oil Source Silicone Liquid Synthetic Ester Mineral Oil

5. Ignition Resistance Mineral Oil 3 mins MIDEL 7131 3 mins Mineral Oil 4 mins MIDEL 7131 70 mins

7. Comparative Biodegradation Rates

9. Moisture Saturation Comparison 220ppm Silicone Liquid 55ppm Mineral Oil 2700ppm MIDEL 7131 Saturation Limit @ 20°C Fluid

10. Breakdown Voltage vs. Relative Moisture Ref: Prof. S. Tenbohlen Stuttgart

11. Moisture Uptake Comparison 90% Humidity Ref: I. Fofana University of Quebec

12. Condensation in Wet Transformers

13. Mineral Oil Low Temperature Breakdown Ref: H. Borsi Schering Institute

14. Synthetic Ester Low Temperature Breakdown Ref: H. Borsi Schering Institute

19. Vattenfall Results – Pilot Phase

20. Vattenfall Results – Long Term

23. Devonport Breakdown Voltage Results

24. Thank-you for listening Hussam Al-Amin – Business Development Manager Tel: +44 161 864 5495 Email: HussamAl-Amin@mimaterials.com