Characterization of series arcs in LVdc microgrids
This paper provides an empirical study on series arc behavior in low voltage dc microgrids. The response of an R-L-C dc microgrid abstraction towards series arcs is studied experimentally for varying grid inductance, dc voltages, load capacitances and load currents. In order to account for the stochastic nature of arcs, experiments are repeated multiple times under similar conditions to gain statistical significance. Thereby, insight on percentage occurrence and burn time of initiated series arcs is provided. Load side voltage response is studied to gain insight on the expected peak drop and fall time. This empirical evidence was judged to be a necessary requirement in developing a novel series arc extinguishing method from load side power electronic devices.
Experimental Observations of the Transient Characteristics of Series dc Arcs with Capacitive Loads
Series arcs can occur in dc power systems whenever an energized wire supplying power to a load is interrupted. This can happen when a wire snaps abruptly or when a load connection becomes loose. Rather than ending in a simple open circuit, the inductance in series with the load establishes an arc, which inserts an additional impedance in between the source and load. The arc impedance decreases load current and complicates detection while still posing a severe hazard. For this reason, the interaction between series arcs and load power converters is of interest. Load converters act as a dynamic input impedance to the arc thus complicating efforts to accurately decouple the interface of arc and load. This paper performs an empirical study of the fundamental interaction between a series arc and fixed impedance, RC load. Both transient and steady state arc behavior are experimentally studied for a fixed series inductance with varying dc supply voltages, load currents, load capacitances as well as terminal gap distances for a spring based separation mechanism. Tests are repeated multiple times at each parameter set to account for the random nature of the arc. It is found that load current and load capacitance dominantly affect the occurrence of sustained series arcs. Results have contributed to formation of a generic arc transient waveform that can be used for further study of the complex interactions between arcs and power-converter loads.
Multiple-dose pharmacokinetics of moxisylyte after oral administration to healthy volunteers.
The pharmacokinetics of moxisylyte in plasma and urine was investigated after oral administration. Twelve subjects were treated orally, twice daily with 240 mg of the drug for 6 days; on day 7, the subjects received a last dose of 240 mg of moxisylyte. Moxisylyte was assayed in plasma and urine by a specific HPLC method with fluorimetric detection. Moxisylyte was absorbed rapidly and changed to its metabolites immediately after drug administration; unchanged moxisylyte was not found in plasma. Two metabolites were found in plasma and urine: conjugated desacetylmoxisylyte (DAM) and the conjugate of desmethylated DAM (MDAM). The pharmacokinetic parameters determined after the first oral administration were not modified on multiple dosing. The apparent elimination half-lives of conjugated DAM and MDAM were 2.3 and 3.5 h, respectively. Elimination of these two metabolites in urine averaged 50 and 10%, respectively.