An Innovative Method for E2 Electrical Endurance Feasibility Study of Circuit Breakers

An E2 class(also known as extended electrical endurance) circuit breaker is designed such that it does not require maintenance of the interrupting parts during its expected operating life. Normally, life expectancy of the design is higher than the expected operating life. Although, it is not a mandatory type test as per internationalstandards, the customer may demand this test duty in addition to the required type test series. An E2 test duty is a highly time consuming and an extremely expensive test. In view of this, an innovative calculation procedure has been developed utilizing the outcome of the cleared type/development test. This will not only save time significantly but will also serve as sufficient proof for performance. Simulations are done only for SF6 circuit breakers and results are presented for both puffer and self-blast type circuit breaker. In order to prove the robustness of the calculation method, simulations have been performed for different frequencies (50 Hz and 60 Hz), rated voltages and short circuit current. The simulation results have been validated by means of testing and are found to be in good agreement with the test results. Further, the calculation procedure can be extended to circuit breakers having different gases/gas mixtures.