A permanent magnetic actuator with scheduled stroke curve for vacuum circuit breakers
The load characteristics of vacuum circuit breakers (VCB) are very close to the output characteristics of permanent magnetic actuator (PMA). The combination of PMA and VCB facilitates the development of phase-controlled switching technology because of its controllability. The operation time dispersion of PMA is very small, but when the actuator is impacted by the change of environment or its components, its dispersion will be unfit for phase-controlled switching. A new type of actuator driving system for PMA was proposed, which was combined with sensors, embedded system and capacitor controlled by high-current power electronic devices. The iron core trajectory of PMA was measured by a displacement sensor and compared to a scheduled action curve, the environment temperature is from a temperature sensor and the current from a Hall current sensor, then compensation to displacement was made based on the adaptive control algorithm and history data in order to match the optimal stroke curve of vacuum circuit breakers. In different conditions, the test results show that the stroke curve was in keeping with the scheduled curve and the operating time dispersion of VCB meets the requirement. The new type actuator driving system can supply an easy-controlled, constant-operating- time execution unit to controlled switching.
Research on breaking capability of triggered vacuum switch for controlled reclosing
Triggered vacuum switch (TVS) has tiny turn-on time, huge power capacity and breaking ability in zero-crossing, and can be used to implement controlled reclosing technology. However, TVS has to break circuit reliably in zero-crossing. The reclosing peak current and transient voltage in 10 kV lines was estimated to determine the electrical transient parameters that the TVS worked with, and then an experiment circuit was designed to test the breaking capability of TVS. The test results showed that TVS successfully interrupted in every time and the breaking capability met the requirement of controlled reclosing.
The Invention of the Jewish People
'All modern nation states have a story of their origins, passed down through both official and popular culture, and yet few of these accounts have proved as divisive and influential as the Israeli national myth. The well-known tale of Jewish exile at the hands of the Romans during the first century AD, and the assertion of both cultural and racial continuity through to the Jewish people of the present day, resonates far beyond Israel's borders. Despite its use as a justification for Jewish settlement in Palestine and the project of a Greater Israel, there have been few scholarly investigations into the historical accuracy of the story as a whole. In this bold and ambitious new book, Shlomo Sand shows that the Israeli national myth has its origins in the nineteenth century, rather than in biblical times - when Jewish historians, like scholars in many other cultures, reconstituted an imagined people in order to model a future nation. Sand forensically dissects the official story - and demonstrates the construction of a nationalist myth and the collective mystification that this requires. A bestseller in Israel and France, Shlomo Sand's book has sparked a widespread and lively debate. Should the Jewish people regard themselves as genetically distinct and identifiable across the millennia - or should that doctrine now be left behind and if the myth of the Jewish state is dismantled, could this open a path toward a more inclusive Israeli state, content within its borders?'