CEA issues ester oil advisory amid West Asia crisis
The Central Electricity Authority (CEA) has issued an advisory directing central, state, and private transmission utilities to use Ester Oil as the insulating and cooling fluid in at least 10% of new transformers, reactors, and other electrical equipment for all voltage classes of 33 kV and above. The move has been linked to the ongoing West Asia crisis and concerns over India’s dependence on imported mineral oil.
The advisory, issued under the CEA (Measures relating to Safety and Electric Supply) Regulations, 2023, states that within the proposed 10% adoption target, utilities are encouraged to maintain a preference for 5% natural ester and 5% synthetic ester. The document does not prohibit the use of mineral oil and clarifies that both mineral oil and ester oil remain permissible under existing regulations.
Safety and supply concerns drive advisory
According to the CEA, mineral oil continues to be the dominant insulating medium across the power sector. However, ester oil technology has already been adopted by a limited number of utilities, including Gujarat Energy Transmission Corporation, NTPC Limited, Power Grid Corporation of India Limited, and Indian Railways. The advisory also notes that Indian standards are available for both oil types.
The CEA cited two key reasons for promoting ester oil adoption. The first relates to safety and environmental considerations. The advisory stated that ester oil is gaining wider global acceptance because of its high fire safety characteristics as well as its biodegradable and environmentally friendly properties.
The second reason is linked to energy security and supply risks. The CEA observed that India largely imports mineral oil, which is derived from crude oil, from overseas markets. The ongoing West Asia crisis was specifically referenced as the basis for urging utilities to implement the advisory at the earliest.
Existing regulations remain applicable
The advisory clarified that it does not supersede any existing statutory requirements. In cases where regulations or applicable standards specifically prescribe dry-type transformers or other technologies, those provisions will continue to apply. In all other situations, utilities may consider ester oil-filled transformers wherever technically feasible.
At the same time, the CEA has outlined conditions for adoption. Utilities have been asked to ensure that transformer designs are compatible with ester oil before procurement. The advisory also requires certification or recommendations from original equipment manufacturers (OEMs) and compliance with applicable technical standards.
No guidance has been issued regarding retrofitting existing mineral oil transformers, and the advisory does not propose any phase-out plan for mineral oil-based equipment.
Industry awaits clarity on implementation
The directive has been approved by the competent authority and signed by Gaurav Srivastava, Assistant Director of the CEI Division. Copies have been circulated to central public sector undertakings, state utilities, Central Transmission Utility of India Limited (CTUIL), PGCIL, State Transmission Utilities (STUs), distribution companies (DISCOMs), generation companies (GENCOs), transmission companies (TRANSCOs), and the Director General of the Indian Electrical and Electronics Manufacturers’ Association (IEEMA).
The advisory leaves several implementation questions unresolved. It does not specify whether the proposed 10% target will function as a compliance requirement or remain advisory in nature. It also does not provide timelines, reporting mechanisms, or details on cost implications associated with ester oil adoption.
For utilities and procurement agencies, the immediate focus is likely to shift toward the availability of ester-ready transformer designs and whether existing procurement contracts can accommodate ester oil variants without requiring fresh tenders. While the advisory repeatedly uses the term “advised,” the reference to the West Asia crisis and the instruction for early implementation indicate growing policy emphasis on diversifying insulating oil usage in the power sector.
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