Customer: Tata Power Delhi Distribution Limited
Location: Delhi, India
Application: Distribution Transformers
Highest Voltage: 11kV
Rating: Various, typically 630kVA
Date: 2010
Tata Power Delhi Distribution Limited (Tata), formally known as NDPL, has a large operating network covering the North and North-West areas of Delhi, serving a population of 5,000,000 people. In common with other Indian utilities in densely populated areas it is under immense pressure from expanding demand on electricity and has embarked on initiatives to improve the distribution network.
Tata identified a large number of mineral oil filled transformers on its network located in densely populated areas, sometimes in the basement of residential buildings. These transformers pose a fire hazard to the occupants of the buildings and a strategy to reduce the fire risk was needed. Following discussions with M&I Materials, a plan was put in place to retrofill a number of distribution transformers in high risk areas of the city with MIDEL oil.
A large amount of support was provided throughout the process, including detailed procedures for pre-testing and retrofilling of mineral oil transformers. Personnel from M&I Materials in the UK went out to India on a number of occasions to provide advice and guidance where necessary. As the retrofills commenced the local M&I Country Head, Nitin Satija, and a UK expert were on site to oversee the retrofill process. They took an active role advising the customer and helping to ensure the initiative progressed successfully.
In total, 21 transformers were retrofilled in this project. These included units which were installed in the basement of apartment buildings. The method adopted by Tata was to transport the transformers back to the workshop and thoroughly drain them, before flushing and refilling the units with MIDEL 7131. This was in line with the guidance from M&I Materials and proved to be a very effective method, leading to remaining mineral oil percentages of less than 3% in most cases.
M&I Materials has continued to work proactively in India to promote the use of synthetic ester fluid, in order to replace flammable, environmentally unfriendly mineral oil. The team continues to work with utilities, standards committees, manufacturers and authorities to help provide solutions for fire safety and environmental protection.