Single Pole Hybrid Switch

Abstract

Electromechanical switching device while making & breaking an electrical circuit is subjected to arcing which is responsible for faster contact wear out, burning of insulation and conductive tracking between the poles. This leads to premature failure and poor electrical life of the device. To avoid the above problem it has been a practice to use solid state switching device. However owing to its high voltage drop across the terminal is subjected to higher conduction loss and hence temperature which demands for higher size, volume and costly heat sink to regulate the temperature within its permissible limits. The present paper reveals about 32A, 240V single pole hybrid switch consisting of low thermal resistance anti-parallel SCR connected across electromechanical AgCdO contacts so that making & breaking current is shared by SCR & continuous load current by contacts. A direct copper, chip and terminal bonding with the Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> or AlN substrate aids in higher thermal conductivity and heat dissipation of the SCR. Experiment result shows no arcing voltage in the voltage waveform during making & breaking of the load. After 1,77,000 number of electrical operation there is no presence of any pit marks, crater formation, carbon deposition or erosion of AgCdO contact material observed.