Charge accumulation and cyclic image transfer on CCD: Search for rapid variations of magnetic field in γ Equ
We search for the variable component of themagnetic field in γ Equ by studying four Nd III lines with the Main Stellar Spectrograph of the 6-m BTA telescope of the Special Astrophysical Observatory via accumulation and cyclic transfer of the electronic image of the Zeeman spectrum on the CCD. The single exposure time was set equal to 1/8 of the spectral variability period. We detected no variable component in the magnetic field of γ Equ with a period of 12.1 min in the November 5/6, 2003 observations.
Combined with six regional grids in China, the security and economy about the voltage levels,transmission,structure and interconnection of synchronized power system are analyzed. It is pointed out that,AC 500 kV synchronized power system can meet the demands of China’s economic development until 2020 year;HVDC and AC 500 kV transmission of independent power sources are its fundamental power supply modes;the branch - like network structure and the hot - standby dynamic reactive power are the solutions to its cascading faults and voltage instability;the regional grid interconnection could be optimized by choosing between controllable(ordinary or back - to - back HVDC) and uncontrollable (extra - high voltage AC) mode according to practical conditions.