EVOLUTIONS IN EXCAVATOR TECHNOLOGY

摘要

The excavation process of removing overburden materials in most opencast mines uses electric rope shovels and walking draglines. These electrical heavy machines have been in operation around the globe for more than several decades. During the last century, up to the late seventies, excavators were traditionally powered by DC generators and DC motors using Ward Leonard controls, known as M-G sets. Caterpillar (formerly Bucyrus) and Siemens AG introduced the tirst AC Drive systems in 1976 on an electric rope shovel. Compared to older M-G set technology, the benefits of AC drive systems can he seen in terms of productivity, efficiency and maintenance costs. AC drive system controls have evolved and each new generation brought advanced technologies to increase productivity benefits through providing higher reliability. The latest systems are equipped with active front-end (AFE) technology, which can adapt to weaker incoming power network even at high peak load demands hy the excavators. These modern technologies can be easily retrofitted in the older generation excavators to take advantage of all their benefits. This article reviews the benefits of modern AC drive systems used in excavators and illustrates their operating advantages.