The European Utility Industry Awards are hosted during European Utility Week, in the evening of the 15th November. The awards recognise and celebrate individuals and projects that have shown outstanding commitment and accomplishments towards a sustainable energy sector. If you have any questions about submissions or voting, please contact us.


This report highlights the journey of Tata Power towards development of fire safe, reduced footprint transformer installation through use of Natural Esters and an optimized design collaboratively developed with transformer manufacturer. The development achieved 17% smaller installation whilst increasing transformer capacity from 20 MVA to 25 MVA whilst ensuring Safe, Compact and Eco-friendly
Electrical Installations.

This report highlights Tata Powers’ collaborative pursuit of compact power transformer using natural ester oil with transformer manufacturers. This resulted in design and installation of a 17% more compact with enhanced capacity from 20MVA to 25MVA whilst ensuring safe, compact and green electrical installation.

Tata Power is one of the lead utilities located in Mumbai the financial hub of India. With over half a million consumer base is a lead adopter of latest technology whilst providing a greener, safer and sustainable environment. Leadership through care is the company`s thrust towards achieving sustainability and safety is one of our core values.

Tata Power commissioned India’s first Natural Ester filled Power transformer

The transformer is a critical link in the Power value chain. It is the heart of an electric distribution utility to step down the transmission voltage to distribution level. Traditional oil filled transformers use paper for insulation and mineral oil for cooling purposes. They have technical limitations and at high fire risk due to low flash & fire points.

Insulation failures due to moisture ingress reduce the lifespan of transformers. Large space requirement and environmental concerns with biodegradability of mineral oil are the other concerns. Natural ester filled transformers were introduced to allow a paradigm shift in the design of transformer itself.

This solution was implemented in a prestigious new smart city hub in India’s financial capital Mumbai housing many financial institutions, a distribution substation with 2x 33/11 kV,20 MVA transformers was planned catering to current and future load requirements. This location has space constraints for safely accommodating conventional mineral oil filled Power Transformers. However it was imperative to install both the transformers in the available space.

Natural Ester Filled Power Transformers, designed to parameters following the new standard IEC 60076-14, resulted in benefits of reduced footprint, enhanced capacity in addition to bringing fire safety and environmentally benign solution.

The design has enhanced capability of 20 MVA to 25 MVA with KNAN and 28 MVA to 30 MVA with KNAF in effect saving investments for increasing load requirements. Tata Power commissioned 2x 33/11 kV, 20 MVA Natural Ester filled Power transformers at this location.

Additionally ageing assets of any electrical utility are a reality; the challenge is not in replacing these assets incurring huge capital expenditure but in enhancing and increasing the life expectancy of existing assets. This involves retro-fitting existing installations and accommodating reengineered solutions in the existing space.

Major milestones in the journey of innovation involve standardisation of key technical particulars viz., flash & fire points, insulation type, OLTC rating, foot print details etc. Joint effort of Tata Power along with Natural ester suppliers and Transformer OEM has resulted in the planned benefits along with added advantage of increased continuous loading of up to 120 % of nominal rating.

Heat run test carried out on the transformer gave encouraging results indicating that further capacity increase – adding value for money- was going to be possible.

At 120 % Loading of 20 MVA, temperature rise for both Oil and Winding well below the guaranteed temperature rise. 

At 140 % Loading of 20 MVA, temperature rise for both Oil and Winding well below the guaranteed temperature rise. 

Going further on the properties of Natural Esters; they are carbon neutral materials. Natural esters produce 56 times less CO2 emissions than mineral oil. Natural Esters are nontoxic and have cleared acute oral and aquatic tests for toxicity. Most importantly natural esters are readily biodegradable. They have a high moisture tolerance leading to far lesser degradation of paper insulation in the transformer.

Tata Power reaffirms its commitment to safely building India’s infrastructure requirement and will continue to uphold and implement technological innovations such as the green transformer with enhanced capacity.  

Natural esters are becoming the preferred alternative to replace mineral oil, in order to improve fire safety and reduced environmental impact. It also enhances performance with at higher temperatures with high temp class insulations resulting in reduced footprint.  This is a major leap towards sustainable solution.



570 Points

Submitted By

Submitted On

30 Sep 2016




It is a breakthrough to the conventional mineral oil filled transformer designs. It addresses the very key challenges utilities are facing today. It starts the revolution of new standards and designs in the way ahead.
Pavitra Gowda's picture


Pavitra Gowda's picture


Jagdeep Sangwan's picture

The requirment in Power Distribution and therefore on  medium and low voltage grid are increasing continuously. Changing direction of power flow load and voltage fluctuations which are caused especially by the strongly growing number of power supplies from volatile power source , e.g photovoltaic / biogasplan and wind farms , make the distribution grid of today go to their capacity limits.

Sanjay Kolte's picture


1. Fire Safe, 2. Space Reduction, 3. Ultimately Solu Btiioodnegradable, 4. Tolerance to Moisture, 5. Enhanced Capacity

Ramesh Kumar's picture

Space optimisation and Safe

Ravindra Gawade's picture

Easter filled transformer is very useful in metro cities like Mumbai as there is space constraint. Also its fire safe property is very important for installation in dense population. 


Benefits of Natural Ester Oil filled Transformers over Conventional Mineral Oil filled Transformers - Enhanced Capacity, Fire Safe, Environment Friendly, Compact in design, Cost Efffective, Tolerance to Moisture resulting in enhanced life of Transformers.

SUHAS SHETYE's picture

Suitable green & fire solution for Metros .

It is worth trying by other utilities .

Naveen Kumar K's picture

Worth trying becauase it is environment friendly,compact,fire safe

Prashant Pai's picture

It is fire free,safe,long lasting