Complex sentence: Fuses have been used as essential safety devices from the early days of electrical engineering, and today there are thousands of different fuse designs which have specific current and voltage ratings, breaking capacity and response times, depending on the application.
Split into simpler sentences: Fuses have been used as essential safety devices from the early days of electrical engineering. Today there are thousands of different fuse designs which have specific current and voltage ratings, breaking capacity and response times, depending on the application.