Effect of Loading, Voltage Difference and Phase Angle on the Synchronisation of a Small Alternator

Synchronisation of small distributed generation, 30 kVA–2 MVA, employing salient-pole synchronous machines is normally performed within a narrow range of tolerances for voltage, frequency and phase angle. However, there are situations when the ability to synchronise with non-ideal conditions would be beneficial. Such applications include power system islanding and rapid generator start-up. The physical process and effect of out-of-phase synchronisation is investigated both through simulation and experimental tests on a salient-pole alternator. There are many factors that affect synchronisation, but particular attention is given to synchronisation angle, voltage difference and, as generators will be loaded during islanding, the load angle. The results suggest that it would be acceptable for the maximum synchronisation angle of distributed generation to exceed that of current practice. Interesting observations on the nature of out-of-phase synchronisation are made, including some specific to small salient-pole synchronous machines. Furthermore, recommendations are made for synchronisation under different system conditions.

Electroreduction of Chlorine Gas at Platinum Electrodes in Several Room Temperature Ionic Liquids: Evidence of Strong Adsorption on the Electrode Surface Revealed by Unusual Voltammetry in Which Currents Decrease with Increasing Voltage Scan Rates

Voltammetry is reported for chlorine, Cl-2, dissolved in various room temperature ionic liquids using platinum microdisk electrodes. A single reductive voltammetric wave is seen and attributed to the two-electron reduction of chlorine to chloride. Studies of the effect of voltage scan rate reveal uniquely unusual behavior in which the magnitude of the currents decrease with increasing scan rates. A model for this is proposed and shown to indicate the presence of strongly adsorbed species in the electrode reaction mechanism, most likely chlorine atoms, Cl*((ads)).

FMRFamide-like peptides (FLPs) enhance voltage-gated calcium currents to elicit muscle contraction in the human parasite Schistosoma mansoni.

Schistosomes are amongst the most important and neglected pathogens in the world, and schistosomiasis control relies almost exclusively on a single drug. The neuromuscular system of schistosomes is fertile ground for therapeutic intervention, yet the details of physiological events involved in neuromuscular function remain largely unknown. Short amidated neuropeptides, FMRFamide-like peptides (FLPs), are distributed abundantly throughout the nervous system of every flatworm examined and they produce potent myoexcitation. Our goal here was to determine the mechanism by which FLPs elicit contractions of schistosome muscle fibers. Contraction studies showed that the FLP Tyr-Ile-Arg-Phe-amide (YIRFamide) contracts the muscle fibers through a mechanism that requires Ca2+ influx through sarcolemmal voltage operated Ca2+ channels (VOCCs), as the contractions are inhibited by classical VOCC blockers nicardipine, verapamil and methoxyverapamil. Whole-cell patch-clamp experiments revealed that inward currents through VOCCs are significantly and reversibly enhanced by the application of 1 µM YIRFamide; the sustained inward currents were increased to 190% of controls and the peak currents were increased to 180%. In order to examine the biochemical link between the FLP receptor and the VOCCs, PKC inhibitors calphostin C, RO 31–8220 and chelerythrine were tested and all produced concentration dependent block of the contractions elicited by 1 µM YIRFamide. Taken together, the data show that FLPs elicit contractions by enhancing Ca2+ influx through VOCC currents using a PKC-dependent pathway.