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Specification & Description
| Specification | Description |
|---|---|
| Part Number | 3TK2821-2CB30 |
| Alternative Part Number | 3TK28212CB30 |
| Manufacturer | Siemens |
| Category | General Automation |
| Product Type | Safety Relay |
| Supply Voltage | 24 V dc |
| Mounting Type | Screw Mount |
| Dimensions | 22.5 x 115 x 105 mm |
| Enclosure Protection Class | IP40 for enclosure, IP20 for terminal |
| Insulation Voltage | Rated at 300 V |
| Ambient Operating Temperature Range | -25 ... +60 °C during operation, -40 ... +80 °C during storage |
| Air Pressure | 90 ... 106 kPa according to SN 31205 |
| Relative Humidity | 10 ... 95 % during operation |
| Installation Altitude | Up to 2,000 m above sea level |
| Vibration Resistance | 5 ... 500 Hz: 0.075 mm |
| Shock Resistance | 8g / 10 ms |
| Surge Voltage Resistance | Rated value 4,000 V |
| EMC Emitted Interference | EN 60947-5-1 |
| Safety Integrity Level (SIL) | Up to SIL 3 according to IEC 61508 |
| Performance Level (PL) | Up to PL e according to EN ISO 13849-1 |
| Category | Category 3 according to EN ISO 13849-1 |
| Hardware Fault Tolerance | 1 according to IEC 61508 |
| Safety Device Type | Type A according to IEC 61508-2 |
| PFHD | 0.0000000011 1/h with high demand rate according to EN 62061 |
| PFDavg | 0.00000099 1/y with low demand rate according to IEC 61508 |
| Proof Test Interval or Service Life | 20 years (T1 value) according to IEC 61508 |
| Number of Safety Contacts | 3 NO (Normally Open) contacts for safety-related instantaneous actions |
| Number of Auxiliary Contacts | 1 NC (Normally Closed) contact for signalling function |
| Control Supply Voltage Type | AC/DC |
| Control Supply Voltage Frequency | 50 Hz / 60 Hz |
| Operating Frequency Maximum | 1,000 1/h |
| Switching Capacity of Contacts | 5 A at 24 V dc, 0.2 A at 115 V ac, 0.1 A at 230 V ac for NO and NC contacts |
| Electrical Endurance | Typical 100,000 switching cycles |
| Mechanical Service Life | Typical 10,000,000 switching cycles |
| Connection Type | Spring-loaded terminals |
| Conductor Cross-section | Solid: 2x (0.25 ... 1.5 mm²), Finely stranded with/without core end processing: 2x (0.25 ... 1.5 mm²) |
| Approvals | BG, SUVA, UL, CSA, EN 60204-1, EN ISO 12100, EN 954-1, IEC 61508 |
| Features | Suitable for protective door monitoring, EMERGENCY-STOP function, and safety switch monitoring |
The Siemens 3TK2821 Series Safety Relay is a vital component designed to ensure the safe operation of machinery in various industrial settings. This particular model, the 3TK2821-2CB30, operates with a 24 V dc control supply voltage and is engineered for secure and reliable integration into emergency stop and protective door monitoring systems.
With its compact dimensions of 22.5 x 115 x 105 mm, this safety relay is suitable for screw mounting, making it a versatile choice for space-constrained environments. The device features spring-loaded terminals, facilitating quick and secure electrical connections.
The 3TK2821-2CB30 is equipped with three normally open (NO) contacts for safety-related instantaneous operations and one normally closed (NC) contact for signalling functions. It supports both automatic and manual start modes, providing flexibility in control strategies.
This safety relay is designed to meet stringent safety requirements, achieving a Safety Integrity Level (SIL) of 3 according to IEC 61508, and a Performance Level (PL) of e as per EN ISO 13849-1. It also boasts a hardware fault tolerance (HFT) of 1, ensuring a robust performance in demanding industrial scenarios.
The 3TK2821-2CB30 is a reliable choice for those seeking a safety relay that combines functionality with safety, all within a design that's easy to install and maintain. Whether used as a standalone unit or as part of a larger safety system, this Siemens safety relay is an essential component for modern industrial safety management.
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Frequently Asked Questions
What is the function of this safety relay?
The safety relay is designed for monitoring safety functions such as emergency stop buttons and protective doors in a machine or plant. It ensures that these safety devices operate correctly and safely interrupt a machine's operation in the event of a hazard.
Can this safety relay be used for monitoring floating sensors?
Yes, it is suitable for monitoring floating sensors, which means it can evaluate signals from devices that do not have a direct electrical connection, such as certain types of emergency stop buttons or position switches.
What are the mounting options for this safety relay?
The relay can be mounted in any position and offers both screw and snap-on mounting options, making it versatile for different installation requirements.
What type of electrical connections does this safety relay support?
This safety relay is equipped with spring-loaded terminals, which allow for quick and secure connections without the need for additional tools.
What is the maximum operating frequency of this safety relay?
The maximum operating frequency of the relay is 1,000 operations per hour, which refers to the number of times it can reliably switch in and out within that period.
What is the insulation voltage rating for this safety relay?
The insulation voltage rated value for this safety relay is 300 V, which indicates the maximum voltage that the insulation can withstand.
What are the dimensions of this safety relay?
The dimensions of the safety relay are 22.5 mm in width, 120 mm in height, and 120 mm in depth, making it compact and suitable for installations where space is limited.
What is the thermal current rating for the switching element of this safety relay?
The thermal current of the switching element with contacts is rated at a maximum of 5 A, which is the current the relay can carry continuously without overheating.
Is this safety relay suitable for use in Class A environments?
Yes, it is suitable for Class A environments, which are typically non-residential and commercial areas. However, it may cause radio-frequency interference in residential environments, and appropriate measures should be taken in such cases.
What certifications does this safety relay hold?
The safety relay holds several certifications, including those from BG, SUVA, UL, CSA, and it complies with standards such as EN 60204-1, EN ISO 12100, EN 954-1, and IEC 61508.
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