Siemens 3TK2821-2CB30 SIRIUS Safety Relay 24V AC/DC 3NO 1NC

Siemens 3TK2821-2CB30 SIRIUS Safety Relay - Advanced Machine Protection

The Siemens 3TK2821-2CB30 represents a breakthrough in industrial safety control technology, delivering fail-safe monitoring for emergency stop circuits, safety gates, light curtains, and two-hand control systems. Engineered with precision German manufacturing standards, this compact 22.5mm safety relay provides reliable protection for personnel and equipment in demanding industrial environments.

Technical Specifications

• Control Voltage: 24V AC/DC (universal input)
• Contact Configuration: 3 NO + 1 NC enabling current paths
• Terminal Type: Spring-type screw terminals for vibration-resistant connections
• Response Time: ≤30ms for rapid safety response
• Operating Temperature: -25°C to +60°C
• Protection Rating: IP20 housing for standard industrial environments
• Mounting Width: 22.5mm DIN rail compatible
• Compliance: EN ISO 13849-1 (Category 4, PLe), IEC 61508 (SIL 3)

Application Scenarios

Manufacturing & Assembly Lines: Integrate with emergency stop buttons and safety interlocks to instantly halt machinery when hazardous conditions are detected, protecting operators during material handling and robotic assembly operations.

Packaging & Conveyor Systems: Monitor safety gates and access doors on high-speed packaging lines, ensuring automatic shutdown when guards are opened during operation.

Metalworking & Press Operations: Deploy with two-hand control stations and light curtains to prevent accidental machine activation, meeting stringent safety standards for press brakes and stamping equipment.

Intelligent Safety Solutions

The 3TK2821-2CB30 features automatic/manual start selection, allowing flexible integration into existing control architectures. Its spring-type terminals eliminate the need for ferrules while ensuring maintenance-free connections that withstand industrial vibration. The relay's redundant contact design provides dual-channel monitoring with cross-circuit fault detection, automatically identifying wiring errors and contact welding conditions.

Common Questions Answered

Q: Can this relay handle both AC and DC control voltages?
A: Yes, the universal 24V AC/DC input accepts either voltage type without modification, simplifying inventory management and installation.

Q: What's the difference between manual and automatic start modes?
A: Automatic start allows the relay to re-energize immediately after fault clearance, while manual start requires deliberate operator reset—choose based on your risk assessment requirements.

Q: Is external monitoring required for this safety relay?
A: No, the 3TK2821-2CB30 includes built-in self-monitoring with diagnostic outputs that continuously verify internal relay function and contact status.

Q: How many safety devices can I connect?
A: The relay supports series connection of multiple emergency stop buttons or parallel connection of safety gates, accommodating complex safety circuits with up to 6 safety input devices.

Warranty & Support

Every Siemens 3TK2821-2CB30 safety relay includes a comprehensive 12-month manufacturer warranty covering defects in materials and workmanship. Our technical support team provides application assistance, wiring diagrams, and compliance documentation to ensure successful integration into your safety systems.

Related Products: Enhance your safety architecture with Siemens 3SK1111-1AB30 SIRIUS Safety Relay Basic Unit for expandable configurations, Siemens 6ES7326-1BK02-0AB0 SM 326 Failsafe Module for PLC integration, or Siemens 3RT1045-1AP00 Power Contactor for load switching applications.

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