Veiki-VNL (Hungary)

HRA studies have for long while depended on a combination of expert judgment estimates, Swain Handbook numbers and from accident reports, see [1] for a critique of HRA methods. Simulator data collection sessions have been carried world-wide [2], including the Electric Power Research Institute sponsored Operator Reliability Experiments [3], the simulator studies sponsored by the USNRC [4] and Electricite De France [5]. There has not been a total acceptance of the fact that simulator is the best approximation to the responses of operators during accident situations and the way to ensure that the HRA represents the actual crews responses to accidents. Training departments carryout a series of accident scenarios and these can be used for HRA purposes.

Summary form only given. The international standard IEC 60076-5 prescribes short-circuit tests to verify the dynamic ability of power transformers to withstand short-circuits. According to the standard, before and after each short-circuit shot, the short-circuit reactance of the transformer shall be measured. The value of changing the inductive reactance caused by the dynamic effect of short-circuit current can be drawn form the conclusion of the changing the geometry of the windings. Therefore, it is a very important electrical parameter of the test object in respect of the qualification of the transformer, so the standard limits the value of changing of the inductive reactance. The High-Power Laboratory of VEIKI-VNL Electric Large Laboratories Ltd. (Budapest) has been performing short-circuit tests on transformers for years such a way, that exceeding the obligatory requirements of the standard they have been measuring the transient pressure waves in the oil tank of the transformer caused by the moving of the windings during short-circuit test. In this paper, the authors introduce their measuring method, circumstances and results.