Siemens 5SY4 supplementary protectors are designed to provide reliable protection for various applications. These protectors are approved according to UL 1077 and CSA 22.2 No. 235-M 89, making them suitable for use in applications up to 277 V AC (1-pole and 1-pole + N designs) and 480 V AC (2-pole, 3-pole, 3-pole + N and 4-pole designs). They offer a modular width of 18 mm and a device mounting depth of 70 mm, ensuring compatibility with a wide range of industrial systems.