Circuit Breaker Performances Selection for Near-to-Generator Fault Current Interruption

Several installations include synchronous generators and, in some cases, synchronous motors. Under short-circuit conditions, the fault currents generated from the synchronous machine are characterized by a high level of asymmetry that requires suitable circuit breaker performances to ensure safe interruption of fault current. To calculate such interrupting performances, which are important for effective circuit breaker selection (IEC Standard discussed in this paper), it is necessary to properly consider: short-circuit current calculation Standards that vary depending on installation type (onshore and offshore), network topology and IEC circuit breaker Standards.A systematic steps approach is discussed referring to a real case study, investigating the symmetrical and asymmetrical components of the fault current and delayed zero crossing phenomena. Additionally, a set of sensitivity analysis is proposed to give the reader an overall feeling about potential critical conditions.