Water and Energy International
Year : 2016, Volume : 58r, Issue : 10
First page : ( 42) Last page : ( 46)
Print ISSN : 0974-4207. Online ISSN : 0974-4711.

Power transformer short-circuit test Procedure, Present and Future capabilities of cPri, High Power laboratory

Chennu Raja Ramamohana Rao, Santhosh J.

Central Power Research Institute, Bangalore

Online published on 8 February, 2016.

Abstract

A power transformer is the single most expensive component in generation, transmission and distribution substations. The importance of the transformer is not only due to its capital cost but the cost of undelivered energy in the event of failure, which makes the financial losses unaffordable. There has been a better understanding of material properties in the last 15–20 years. Transformer manufacturers are exploiting this better understanding and produce transformers of smaller size with saving of material and transport costs. Unfortunately, this has led to both conductor and insulating material operating close to their limits and an increase in failure in the early years of transformer life. The rapid growth of power systems has given a raise to increased fault levels and the transformers should be able to handle the fault currents to ensure the reliability of the power system. The transformer must be designed to withstand these short circuits. The short circuit testing on the transformer is the effective way of determining its integrity for stresses.

When the single phase short circuit testing of the power transformer is carried out the line current measured depends on the vector group of the transformer. This paper explains the test procedure for short circuit testing of the transformer as per IEC 60076-5 & IS 2026-5 and the relation between line and phase currents, when the test is carried out in single phase method for different vector groups for both line to neutral method and one half phase method. The CPRI experience of testing high power transformer is also explained. This paper describes the CPRI High power laboratory's test capabilities, on-going and future expansions are also discussed.

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