A facility for electrical contact resistance measurement

A test facility was developed for directly measuring the electrical contact resistance of switch gear contacts of real sizes under different environmental conditions and contact pressures. It can measure contact resistance to an order of one-tenth of a mu Omega. It sources a constant current in the order of mA and hence avoids Initial arcing across contacts, Experiments were conducted on brass-brass samples with different contact pressures and the results are in agreement with published theoretical calculations

An improved maximum power point tracker using a step-up converter with current locked loop

lt is well known that for a given solar radiation intensity and solar cell temperature there exists a Maximum Power Point at which the power generated from the PV panel is at its maximum. A system designer is interested in optimal matching of the load to the PV generator so that the maximum power can be obtained during operating period. A Maximum Power Point Tracker (MPPT) using a step up converter with a current locked loop is developed. Its performance is compared with the literature (the step down power converter using PWM technique), under different solar irradiance and ambient temperatures. It showed an improvement in the output power by 22.5% (average) over a wide range of solar irradiation in a day