A single-phase grid-connected converter is usually adopted in low-power renewable systems. This paper deals with a novel five-level converter topology that follows this development.. The proposed converter architecture is based on a full-bridge topology with two additional power switches and two diodes connected to the midpoint of the dc link. Since the two added levels are attained by the discharge of the two capacitors of the dc link, the midpoint voltage is balanced and obtained with a specific pulse width modulation (PWM) strategy. This solution is designed for renewable energy systems, where unity power factor operations are generally required. Never the less, a variation of the proposed topology which allows four-quadrant operations.

The current transformer is one of the types of instrument transformer which is designed in such a manner so as to produce a current in its secondary circuit which in turn proportional to the current flowing through it’s primary circuit. It is one of the components that needs to be installed inside the electrical panel board in order to measure the current flow through each phase of the three phase system inside the panel. Usually these electrical panel boards were designed by electrical based industries. One of such industries which was in need of a 50:5 ratio current transformer had handed over the current transformer design and manufacturing as an industrial work to the authors. In this paper the authors deal with the optimal design and re-engineering and testing of the current transformer that is used in the measurement of current.