Recently, the Central Electricity Authority (CEA) issued draft revised guidelines on type tests and the model quality assurance plan for major power sector equipment. The drafts comprise the Guidelines for Type Tests for Major Equipment of Power Sector and the Guidelines for Model Quality Assurance Plan (MQAP) for Major Equipment of Power Sector, superseding the earlier 2022 guidelines, which were made mandatory under the CEA (Technical Standards for Construction of Electrical Plants and Electric Lines) Regulations, notified on December 23, 2022. The revision follows a decision taken during a Revamped Distribution Sector Scheme weekly review meeting, where it was agreed to discontinue inspections at manufacturer premises and direct the CEA to review the MQAP.
Guidelines for draft type test
The purpose of these guidelines is to set uniformity in how often type tests are conducted, as current practices result in inconsistencies in acceptance across utilities and stakeholders. These aim to reduce the repetitiveness of type tests, especially when no major changes have been made to the design, technology, materials, mechanical construction, functionalities or performance specifications of the equipment, thereby saving cost, time and resources for manufacturers, vendors, utilities and end consumers. Additionally, the guidelines seek to prevent overloading and long waiting times at testing facilities by avoiding unnecessary repetitions.
The guidelines for type tests establish the framework for conducting, documenting and validating the type tests of power sector equipment. Type tests should preferably be conducted in India for equipment with local testing facilities, while equipment without domestic facilities or imported items can be tested in accredited foreign laboratories. In-house tests by manufacturers are acceptable if conducted in accredited labs and witnessed by utility or CEA representatives. All test results must be thoroughly recorded in type test reports with detailed information, including ratings, drawings, model numbers, test circuits, calculations, photographs and compliance with relevant standards. Type test reports should be issued within 30 days of test completion and have traceability.
Type tests generally do not need repetition unless there are changes in design, materials, manufacturing processes or relevant standards. Minor changes that do not affect functionality or reliability do not require retesting, while major changes or revisions in standards necessitate repeating tests for affected parameters. Component changes are not a reason for repeating type tests if the new components have already been successfully tested and do not affect performance. Utilities may request repeat tests at their own cost, but this should not become standard practice.
The guidelines allow extending the validity of type test results to similar designs or equipment operating under lower stresses, provided materials and manufacturing processes remain unchanged. For complex assemblies like gas insulated switchgear, performance can be validated using representative subassemblies. For high voltage capacitors, successful type tests apply to units with lower design stress, while for low voltage capacitors, tests are valid for units with the same voltage and lower output kVAR if design, materials and processes remain consistent.
Specific provisions have been made for the hydropower sector, recognising that turbines, pump-turbines, reversible turbines and generators are tailored to project-specific parameters such as head, discharge, speed and capacity. Each turbine and generator type, along with its components, is uniquely designed for the project, making uniform type test periodicity impractical. Only components or auxiliaries with long-term stability and minimal design changes are covered for extended type test validity.
The type test guidelines specify validity periods for test reports based on equipment type: transmission equipment of 66 kV and above is generally valid for 10 years, distribution equipment below 66 kV for five years, thermal equipment for five years, major control and instrumentation equipment for 10 years, and hydro sector equipment for 10 years. Exceptions include gas-insulated and hybrid switchgear, which are valid for 15 years, generator circuit breakers for 20 years, and smart meters for three years, compared to five years for other energy meters.
Draft guidelines for MQAP
The uniform guidelines for the MQAP aim to develop efficient MQAPs with comprehensive coverage of essential tests while eliminating unnecessary repetitions, standardising sample sizes and optimising customer hold points (CHPs) by accepting test certificates for non-critical tests. The guidelines seek to harmonise QAPs across manufacturers and utilities through uniform standards and to prevent the overloading of limited testing facilities by aligning with guidelines on type test validity and reducing the duplication of non-critical tests.
The guidelines for the MQAP outline a standardised framework that utilities, purchasers, developers and suppliers must follow to ensure the quality and reliability of power sector equipment. The guidelines provide model QAPs for different categories of equipment, including substations, switchyards and transmission lines; major equipment in hydropower plants; major equipment in thermal power plants; and distribution system equipment. For electromechanical equipment not covered under these annexures, the MQAP provisions are left to mutual agreement between manufacturers and purchasers. Test certificates for bought-out items, once reviewed and found to meet purchaser requirements, are considered acceptable. Manufacturers must also incorporate any changes in acceptance norms or testing practices arising from national or international standards and submit these revisions for purchaser approval.
The guidelines also prescribe limits on the maximum number of CHPs and sampling sizes that developers or purchasers can specify, ensuring conformity with applicable standards. While these represent the maximum requirements, suppliers and purchasers may agree to identify fewer CHPs to save time, based on specific needs. Purchasers retain the right to request additional tests not included in the MQAP, but such requests should not become routine. Any additional tests must be specified at the contract stage, quoted separately in the price bid, and the utility must provide extra time for their completion.
Test certificates prepared by the supplier for raw materials, in-process checks and initial stages are only considered valid after purchaser review and acceptance at the designated CHP. The extent of checks is to be strictly maintained, governed by the relevant acceptance norms. For instances where “sample per lot” is indicated, a minimum of two samples or 5 per cent of the lot, whichever is higher, is mandated, except for type tests. Despatch of equipment from the manufacturer’s works can only take place after acceptance, following pre-despatch inspections by the purchaser’s authorised representative. Purchasers may, however, waive inspection requirements if deemed necessary. If materials are despatched without prior acceptance, resolution procedures must be defined in the contract.
The guidelines further stress the importance of maintaining calibrated testing and measuring instruments. Manufacturers must ensure the periodic calibration of all equipment in line with the National Accreditation Board for Testing and Calibration Laboratories guidelines, with records of calibration and equipment identification maintained for purchaser verification. Equipment undergoing repair must be recalibrated, and all calibrated devices sealed to prevent manipulation. In certain cases, recalibration may be required in the presence of a purchaser’s inspector. Lastly, compliance with the latest CEA (Technical Standards for Construction of Electrical Plants and Electric Lines) Regulations is mandatory, ensuring that minimum technical requirements are met for generating stations, transmission and distribution lines, and substations.
Conclusion
Overall, the CEA’s guidelines aim to strengthen quality assurance and ensure the standardisation of equipment in the power sector. By streamlining the periodicity of type tests and harmonising the MQAP, the guidelines aim to remove redundancies, reduce costs and ensure consistency across stakeholders while improving the efficiency of testing infrastructure.
