Synthetic testing under short-line fault conditions. Comparison tests using an air-blast circuit breaker

The paper is a contribution to work on the problem of synthetic testing under short-line fault conditions. Traditional `current-injection¿ circuits for terminal faults have already been extended to the case of the short-line fault by various authors. The circuit which is proposed in the paper accurately reproduces an actual short-line fault occurring in a network under most general conditions. The test circuit is described, and a survey is given on a complete series of tests carried out at CESI Laboratories, with the object of comparing synthetic and direct methods of testing. Test results have shown that the synthetic circuit adopted complies with the requirements for equivalence to the corresponding direct circuit. A confirmation of the results is given both by statistical analysis and by current-zero measurements, which allow a better insight into the interaction between test breaker and test circuit.