One of the biggest problems in Power Quality is the disconnection of electric motors due to the presence of sags. In order to study this phenomenon it became necessary to build a sag generator to, for example, develop immunity curves for induction motors as well as for synchronous motors. In this way it is possible to evaluate the quantitative impact of sags in these machines. This paper also analyzes the effects in current, torque and speed caused by sags, in particular A, B and C types.
Read full article
This paper deals with PFC units design related problems in case of installation in harmonics rich environments: in particular the paper contains an overview of sizing approach used in a real case of PFC units design for installation in a steel factory where new PFC units installation has been necessary after a fault with catastrophic consequences for the existing ones. The document contains a report on stresses calculation on PFC units due to harmonic currents generated by non linear loads installed in the above mentioned plant.Read full article
We present the progress of a new project, a field demonstration of a multiple power quality supply system. The project is the first trial to take place in Japan in the area of power quality concepts and solutions. For this project, NTT Facilities developed and installed a multiple power quality supply system that has the capability to feed four classes of alternative current (AC) and one of direct current (DC) power while meeting various customer requirements.Read full article
When a river runs into the ocean and fresh water mixes with saltwater, huge amounts of energy are unleashed. Unlike violent torrents in a waterfall or steaming hot geysers, the energy released cannot easily be seen from the banks of the estuary. Nevertheless, the energy is there, and everyone who has tried to separate salt from seawater knows that large amounts of energy are needed.Read full article