Core Features 3-Pole Thermal-Magnetic Protection for High-Power Circuits: Functions as a 3-pole molded case circuit breaker (MCCB) designed to safeguard low-voltage industrial power distribution systems (e.g., main feeder circuits, large motor drives, or process machinery) from overloads, short circuits, and phase imbalances. It integrates two critical protection mechanisms: Thermal overload protection: Uses a bimetallic strip that heats and bends under sustained overcurrent (e.g., from motor overloads or excessive load draw), triggering a delayed trip to avoid false shutdowns caused by temporary inrush currents (e.g., motor start-up). Magnetic short-circuit protection: Employs a high-speed electromagnet that reacts instantaneously (<10ms) to extreme fault currents (e.g., phase-to-phase shorts or ground faults), limiting arc flash hazards and minimizing damage to wiring, transformers, and connected equipment. This dual protection makes it ideal for critical high-power circuits in manufacturing plants, data centers, or large commercial facilities. High-Power Electrical Ratings: Rated for AC 400V/415V (50/60Hz) (standard industrial three-phase line voltage) with a rated current (Iₙ) of 50A and a short-circuit breaking capacity (Icu) of 50kA at 415V. These specifications support heavy loads such as: Large 3-phase motors (up to ~22kW). Main feeder circuits for multiple machine groups. High-power process equipment (e.g., industrial ovens, compressors, or CNC machining centers). The 3-pole design ensures all three phases (L1, L2, L3) disconnect simultaneously, eliminating the risk of single-phasing (a leading cause of motor burnout). Robust Molded Case Construction: Housed in a flame-retardant thermoset plastic case (UL94 V-0) with a reinforced metal frame for mechanical strength and impact resistance. The molded case is designed to contain arc flashes during short circuits, reducing fire and injury risks. It meets IP30 protection (IEC 60529), shielding internal components from dust and accidental finger contact—suitable for installation in electrical switchgear, motor control centers (MCCs), or dedicated breaker panels. The large, ergonomic toggle handle provides clear visual status (on/off/tripped) and requires manual reset after a trip, with a lockable option to enforce LOTO (Lockout/Tagout) protocols during maintenance. Reliable Contact & Terminal Design: Features silver-alloy main contacts with high arc resistance to withstand repeated switching and fault events, ensuring long-term durability (≥5,000 mechanical operations and ≥100 full-load breaking cycles). The terminal blocks use compression-type screw connections compatible with 6–16mm² copper/aluminum wires (solid or stranded), with wide terminal openings for easy wiring and secure torque retention. Additionally, the breaker includes a built-in trip indicator that remains in the “tripped” position until reset, providing clear fault visibility for technicians to diagnose issues (e.g., overload vs. short circuit). Flexible Integration & Smart Compatibility: Designed for panel mounting (via bolt-on lugs) into standard electrical switchgear or MCCs, with dimensions optimized for space-efficient installation alongside other protection devices (e.g., contactors, overload relays, or surge protectors). It supports optional auxiliary contacts (for remote status monitoring) and shunt trips (for remote shutdown), enabling integration into building management systems (BMS) or industrial automation platforms (e.g., Siemens SIMATIC). The breaker also complies with selective coordination requirements, allowing it to trip only during faults in its protected zone—avoiding widespread power outages. Global Safety & Industry Certifications: Meets stringent international standards including IEC 60947-2 (low-voltage switchgear and controlgear: circuit breakers) and EN 60947-2 (European equivalent), ensuring compliance with regional electrical codes (e.g., IEC 60364 for global markets, NFPA 70/NEC for North America, BS 7671 for the UK). It is certified for use in harsh industrial environments, with resistance to vibration (10–500Hz, 2G) and extreme temperatures (-25°C to +70°C), ensuring reliable performance in demanding conditions. Typical Applications The Siemens Switch 3LD2555 is engineered for high-power circuit protection in industrial and large commercial settings, with core use cases including: Main Feeder Circuit Protection: Installed as the main breaker in industrial electrical panels to distribute power to downstream circuits (e.g., machine groups, lighting, or auxiliary systems). The 50kA breaking capacity handles system-level fault currents, while the 50A rating matches medium-sized facility power demands. Large 3-Phase Motor Protection: Used in motor control centers (MCCs) to protect 3-phase motors (e.g., conveyor drives, pumps, or compressors) up to ~22kW. The thermal-magnetic protection prevents motor burnout from overloads and shields wiring from short-circuit damage. Process Machinery Power Circuits: Deployed to protect high-power process equipment (e.g., industrial ovens, plastic extruders, or CNC machining centers) that requires consistent, uninterrupted power. The 3-pole design ensures balanced phase distribution, critical for equipment with sensitive electronics. Data Center Sub-Feeder Circuits: Used in data centers to protect sub-feeder circuits powering server racks or cooling systems. The high breaking capacity minimizes downtime during faults, while optional auxiliary contacts enable remote monitoring of breaker status via BMS. Commercial Building Heavy-Duty Circuits: Installed in large commercial buildings (e.g., malls, hospitals, or airports) to protect heavy-duty systems such as HVAC chillers, elevators, or kitchen equipment. The lockable handle supports LOTO compliance, ensuring safe maintenance.