Complex sentence: The British Rail Class 71 was an electric locomotive used on the Southern Region of British Railways, unlike most other Southern Region electric locomotives (such as classes 73 and 74) they could not operate away from the electrified (750 V DC third rail) system.
Split into simpler sentences: The British Rail Class 71 was an electric locomotive used on the Southern Region of British Railways. Unlike most other Southern Region electric locomotives (such as classes 73 and 74) they could not operate away from the electrified (750 V DC third rail) system.