In its new draft guidelines on type-testing of major equipment used in the power value chain, Central Electricity Authority (CEA) has prescribed that no repetition of short-circuit test would be required for transformers owing to mere change in type of bushing or on-load tap changer (OLTC).
This is provided that the bushings and OLTC of supplied make have same or better rating and have been successfully type-tested as per relevant IS/IEC.
This is just one of the several broad guidelines that CEA has proposed in the new draft “Guidelines for the Periodicity of Type Tests for Major Equipment used in Electrical Power System,” on which CEA is seeking feedback from stakeholders, by November 29, 2024.
The basic objectives in issuing these guidelines are:
- To set uniformity in the periodicity of type tests
- To reduce the repetitiveness of type tests, wherever possible
- To avoid overloading/overcrowding of testing facilities
These guidelines cover 63 types of equipment used in the power value chain, and prescribe a minimum validity of 10 ten years for the type-test results provided that there has been no change in: the design after the type tests, the material, the manufacturing process and the manufacturing quality plan.
In some equipment like outdoor circuit breaker, outdoor isolator, gas-insulated switchgear (GIS) and hybrid switchgear, ring main unit (RMU), the prescribed periodicity of the type tests has been proposed at 15 years.
What is a type-test?
A type-tests, also called ‘proof test’ is basically a design validation test that the purchaser must satisfy itself with by following an agreed quality assurance plan and special tests, if any, agreed between the buyer and the supplier/manufacturer. Such tests are not required to be performed on each unit of the equipment but are performed on a representative design of the equipment.
Rationale for new guidelines
These new draft guidelines have been issued in the wake of representations received by CEA citing non-uniformity of the periodicity of the type tests of the same equipment to be used in different segments of power value chain – generation, transmission and distribution. The objective is to harmonize and rationalize the periodicity of type tests and also to incorporate the provisions regarding the effective date of type test in respect of various equipment.
Prior to this, guidelines on the subject matter were issued in 2022, known as “Guidelines for the Type Test Validity of Major Equipment of Power Sector, 2022.”
The detailed draft guidelines may be accessed using this external link
Featured photograph, sourced from Transformers & Rectifiers (India) Ltd, is for representation only
