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Comparative Study of Synthetic Test Circuits for Testing of MV and HV AC Circuit Breakers According to IEC Std. 62271

Ratings of circuit breakers are currently as high as 1100 kV of rated voltage and at the same time 63 kArms of short circuit rated current to enable developments of power transmission grids up to Ultra High Voltage levels of 1100 kV and more. These voltage and current ratings correspond to a rated short circuit power of 120 GVA. Testing of such highly rated circuit breakers is not feasible with direct circuits where the short circuit power is to be supplied from power grid directly or by means of large synchronous generators. Synthetic test circuits are widely used to reproduce the switching conditions of circuit breaking by separating high current and high voltage phases of the switching process and thus allowing to significantly increase the testing capabilities of short-circuit laboratories. The aim of this paper is to present simulations of three principle synthetic test circuit topologies and to discuss their applicability for development of synthetic test circuit at a short circuit laboratory. The simulations are conducted with the use of EMTP-ATP package for Parallel Current Injection Synthetic Test Circuit (STC), Series Current Injection STC, and Voltage Injection STC. The aim of the simulations presented in this paper is to evaluate testing conditions in the circuits analyzed to ensure the equivalence between synthetic and direct testing with required accuracy and acceptable development and operational efforts.