Siemens 5SY4 supplementary protectors are designed to provide reliable overcurrent protection in a variety of industrial applications. These protectors are UL 1077 and CSA 22.2 No. 235-M 89 approved, making them suitable for use in circuits up to 277V AC (1-pole and 1-pole + N designs) and 480V AC (2-pole, 3-pole, 3-pole + N and 4-pole designs). They are available in various configurations to accommodate different circuit requirements and offer a robust solution for protecting sensitive equipment.