Overview
The ABB S281UC-Z0.5 is a single-pole miniature circuit breaker designed for direct current (DC) applications up to 250VDC. This compact device provides reliable branch-circuit protection in industrial automation, PLC systems, instrumentation, and renewable energy installations. The S281UC-Z0.5 combines ABB’s proven design with space-saving DIN-rail mounting for integration into control panels and switchboards.
Key Features
- Single-pole, single-phase DC miniature circuit breaker
- 0.5A nominal current rating with Z-trip curve (for sensitive loads and instrumentation)
- 250VDC rated voltage (also compatible with 500VDC operation in select configurations)
- 10 kA breaking capacity at rated voltage
- UL 1077 certified for North American industrial use
- Compact DIN-rail mount design for panel integration
- Manual reset with lever-action trip mechanism
Technical Specifications
The S281UC-Z0.5 is engineered to IEC and UL standards for DC circuit protection. Key parameters include:
- Rated Voltage: 250VDC (UL 1077)
- Rated Current: 0.5A
- Poles: 1 (single)
- Trip Characteristic: Z (high-sensitivity, designed for electronic circuits and instrumentation)
- Breaking Capacity: 10 kA at rated voltage
- Mounting: DIN-rail (35 mm standard)
- Operating Temperature Range: -25°C to +70°C
- Certifications: UL 1077, IEC 60947-2
- Manual trip lever and reset mechanism
Typical Applications
- PLC and Industrial Control Systems: Protection of low-voltage DC power supply branches in programmable logic controllers and distributed I/O modules.
- Instrumentation Circuits: Branch protection for analog signal conditioning and sensor power supplies requiring sensitive trip points.
- Renewable Energy Systems: Solar or wind microgrid protection where 250VDC DC bus architectures are common.
- Laboratory and Test Equipment: Branch-circuit protection for precision measurement and control circuits with low current draws.
- Telecommunications and IT Infrastructure: 48VDC and 250VDC distribution protection in data centers and telecom equipment enclosures.
Compatibility & Replacements
The ABB S281UC-Z0.5 is compatible with standard IEC 60947-2 DIN-rail mounting systems and works directly with auxiliary contact kits (such as S2-H11 and S2C-H6RU add-ons) for remote monitoring. The related S230UC series offers multi-pole configurations for three-phase AC and DC applications. For different current ratings within the same family, ABB offers the S281UC series in ratings from 0.5A through 63A with identical dimensions and mounting footprints. When replacing older miniature circuit breakers, confirm voltage rating and current sensitivity to ensure proper load protection and compatibility with panel layout.
