Multifunction realization of active electronic current transformer
In order to fit for the urgent requirement of the digital substation, the research of electronic current transformer (ECT) attracts more and more attention. The multifunction of ECT is especially studied in order to expand its application range. In this paper, a type of active ECT is introduced firstly. The redundant backup design of high-voltage circuit is presented after that. It will be greatly helpful for the improvement of stability and reliability of active ECT. The multifunction of lowvoltage side circuit is also discussed carefully. The local display, harmonic analysis and remote communication between ECT and master computer are all designed and realized. Therefore, the application field of active ECT will be expanded significantly. The validities of above circuits are all illustrated in Lab at last.
A new calibration method of electronic transformer applied in power system
In this paper, a new calibration method is proposed to fulfill the requirement of calibration of electronic transformer. At first, the fast measurement method of power frequency is presented. And then the principle of Quasi-synchronous DFT algorithm is introduced in order to satisfy the special requirement of fast harmonic analysis during the calibration of electronic transformer. Therefore the amplitude error and phase error of electronic transformer could be obtained based on this new calibration method. The performance of method is verified by simulation results.
Influence of inducers and inhibitors on the metabolism in vitro and neurochemical effects in vivo of MDMA.
(S)-(+)- and (R)-(-)-3,4-methylenedioxymethamphetamine (MDMA) were metabolized in vitro by rat liver microsomes via N-demethylation to 3,4-methylenedioxyamphetamine (MDA). Whereas no difference was found in the biotransformation of the two enantiomers in the male rat or in the phenobarbital (PB) treated animals of either sex, more than twice as much MDA was formed from (S)-(+)- than from (R)-(-)-MDMA in the untreated female rat. Although 3-methylcholanthrene (3MC) pretreated rat liver microsomes were less active than those from the untreated rats of the same sex, they formed more MDA from (+)- than from (-)-MDMA. The enantioselective metabolism thus appears to be associated with the relative abundance of individual cytochrome P-450 isozymes. (S)-(+)- and (R)-(-)-MDMA.HCl (20 mg/kg) were about equipotent in depleting serotonin (5-HT) levels in the frontal cortex at 3 hrs and 1 wk following oral administration to female rats. Pretreatment of rats with SKF-525A attenuated and that with PB enhanced the 5-HT depleting potential of either isomer at 3 hrs. The 5-HT depleting potency of (+)-MDMA was significantly greater than that of its (-)-antipode at 3 hr in PB pretreated, but not in SKF-525A pretreated animals. The results suggest that the neurochemical effects of MDMA are caused by the formation of an active metabolite in vivo, and since both enantiomers were N-demethylated in vitro to approximately the same extent by PB pretreated rat liver microsomes, the active metabolite may be other than MDA.