Complex sentence: Cauvery Basin Refinery, a subsidiary of CPCL is located near Nagapattinam was established in 1993, is a major contributor to the economy of the town.
Split into simpler sentences: Cauvery Basin Refinery, a subsidiary of Chennai Petroleum Corporation Limited (CPCL) is located near Nagapattinam. Established in 1993, it is a major contributor to the economy of the town.