Siemens 5SJ4320-6 Three-Phase Circuit Breaker

Siemens SENTRON 5SY4320-6 three-pole miniature circuit breaker provides 20 A protection for 3‑phase circuits up to 400 V AC, with a robust short‑circuit breaking capacity of 10 kA and a 70 mm housing depth, compatible with standard distribution panels. This Type B (curve B) device trips quickly on moderate overcurrents, making it suitable for general‑purpose protection of motors, transformers, and lighting loads in commercial and light‑industrial installations, while its common‑trip mechanism ensures all three phases disconnect together. The 5SY4 family designation denotes a modular, compact protection device designed for reliable use in panel boards and switchgear, with three poles interrupting L1–L3 in a three‑phase network. The datasheet notes a 55°C rated ambient value, supporting reliable operation in typical indoor environments, and the device is rated for 400 V AC systems with a 10 kA breaking capacity, balancing safety and performance in protection schemes for feeders, distribution panels, and machine control cabinets.