Progressive utility chooses MIDEL for retrofill project


Customer: CESC Ltd
Location: Kolkata, India
Date: 2016

Application: Distribution Transformers, Retrofilling
Highest Voltage: 6/11kV
Rating: 400kVA

Featured Products: Midel 7131



An fire-safe alternative to costly dry-type

CESC Limited is a power utility providing electricity within 567 sq. km of the Kolkata area. More than a century old, it is the oldest power company in India, dealing with the entire span of electricity business including Generation, Transmission and Distribution. It serves approximately 3 million consumers including domestic, industrial and commercial users.

CESC operates on a wide range of assets in power generation and distribution. There are more than 8,000 distribution transformers in the system, the majority of which are rated between 315 and 500 KVA.

CESC has been installing Dry Type transformers in densely populated areas since 1990. Today, around 25% of those assets are Dry Type Transformers. As an alternative to fire prone mineral oil transformers and costly dry type transformers, CESC is considering fire safe and environment-friendly ester oil filled transformers as a possible solution.


The retrofill pilot candidates

CESC chose retrofilling with MIDEL 7131 for three main reasons:

  1. The fire safety advantages over mineral oil (and cost savings versus dry type transformers)

  2. Environmental protection, since synthetic organic ester is officially classified as readily and fully biodegradable.

  3. And the moisture tolerance - Ester fluids are much more tolerant of moisture ingress than mineral oil. In areas prone to wet conditions, retrofilling transformers with ester fluids will lead to increased reliability.


Location - Plastic factory in densely populated area (recently installed)

Retrofilling - On-site

Rating of Transformer - 400kva/11/6kV

Application - Fire safety, environmental protection and high temperature operation


Location - Manufacturing workshop, close proximity to a school

Retrofilling - On-site

Rating of Transformer - 400kva/11/6kV

Application - Fire safety, environmental protection and high temperature operation


Operational success with MIDEL 7131

After rigorous testing by CESC, the two transformers are now in full operation and contributing to the reliable service that CESC is committed to providing to its customers in Kolkata.

Mr. Nitin Satija of M&I Materials commented “We worked very closely with CESC officials to demonstrate how MIDEL 7131 could provide enhanced levels of fire safety and environmental protection for transformers. In addition, the proposal made financial sense, as the transformers will now have a longer operational life and will perform at a higher level than before.




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