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Marvo Part ID: MV-2EZC

£74.34 (ex. VAT)


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Specification Description
Part Number 3TK2841-1BB40
Alternative Part Number 3TK28411BB40
Manufacturer Siemens
Product Family Safety Relay
Supply Voltage 24 V DC
Mounting Type Screw and Snap-on Mounting
Dimensions Width: 22.5 mm, Height: 100 mm, Depth: 88 mm
Electrical Connection Screw-type Terminals
Conductor Cross-section Solid: 1x (0.5 ... 4 mm²), 2x (0.5 ... 2.5 mm²), Stranded: 2x (20 ... 14)
Product Functions Light barrier, protective door, automatic start, laser scanner, light grid, emergency stop, and step mat monitoring
Safety Integrity Level (SIL) SIL3
Performance Level (PL) PL e
Category Category 4 according to EN ISO 13849-1
Hardware Fault Tolerance 1
Safety Device Type Type B according to IEC 61508-2
Ambient Operating Temperature -25 … +60 °C
Protection Class IP Enclosure: IP40, Terminal: IP20
Certificates/Approvals UL, CSA, TÜV, BG BIA, and others

Commonly Asked Questions

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We accept card payments from all major credit, debit and Mastercard providers including Visa, American Express, Western Union, Paypal and bank transfers. Before you complete an order you will be prompted to input your payment details, at which point you can enter the relevant card information you wish to use for your transaction. If you are experiencing issues with your payment method then you can contact our team via email here. From there, you will be directed to the most relevant resource or person to help you complete your payment, get your order processed and ensure that your parts are on the way to your delivery address.


Is my order covered by a warranty?

Marvo provides a full 12-month warranty on all products, whatever the condition. For your peace of mind, all parts are ‘Marvo Approved’ which means that they have been tested and checked to ensure that they are in working condition. If you are unhappy with the part(s) you received and would like to request a return, you can do so by completing our quick and easy online form. Once we have received your Returns Request, a member of the team will be in touch to discuss this further with you. You can read more about our warranty policy here.


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Marvo currently delivers to the United Kingdom (excluding Northern Ireland), the United States of America and Germany. If you cannot find your delivery address at checkout, this is most likely because Marvo does not currently deliver to this location. There are ongoing efforts to make Marvo accessible to a global market, keep your eyes peeled as our service expands to new locations. All orders are sold with a streamlined delivery process ensuring that you get your part, fast. Marvo is designed to offer you quick, easy and reliable access to critical components and uses well established global shipping services, including but not limited to DHL, UPS and FedEx.


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Marvo is a highly credible supplier of industrial automation parts and components with dedicated hubs around the world offering industry-leading products and services.  Marvo is committed to providing a quick, easy and reliable place to source your automation and control components. All purchases come as standard with a comprehensive 12-month return to base warranty meaning that, in just a few clicks, you can source critical parts more seamlessly than ever before. Click here to read an article on how Marvo is redefining convenience for automation and manufacturing professionals.


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3TK2841-1BB40 Product Description

The Siemens 3TK2841 Series Safety Relay is a vital component designed to ensure the safe operation of machinery in various industrial settings. This safety relay, with its 24 V dc operating voltage and convenient screw mount design, is engineered to integrate seamlessly into your safety systems. Its compact dimensions of 23 x 120 x 120 mm make it an ideal choice for applications where space is at a premium.

Crafted for reliability, the 3TK2841-1BB40 model boasts electronic enabling circuits (EC) and is capable of handling both single-channel and two-channel safety-related wiring of inputs, providing flexibility in system design. The device is also equipped with two instantaneous safety-related semiconductor outputs, enhancing its functionality in critical safety applications.

This safety relay is suitable for a variety of safety functions, including light barrier monitoring, protective door monitoring, emergency stop functions, and pressure-sensitive mat monitoring, among others. Its design allows for both automatic and monitored start modes, giving you the control needed for different operational requirements.

The 3TK2841-1BB40 is designed to meet stringent safety standards, achieving a Safety Integrity Level (SIL) of 3 and a Performance Level (PL) of e, as per EN ISO 13849-1. It also conforms to Category 4 according to EN 954-1, ensuring a high level of reliability and safety for your machinery.

With certifications from TÜV, UL, and CSA, this safety relay is recognised for its quality and compliance with international safety regulations. Its robust construction and finger-safe terminals provide additional protection against electrical shock, making it a safe choice for operators and maintenance personnel alike.

In summary, the Siemens 3TK2841-1BB40 Safety Relay is a dependable and versatile solution for enhancing the safety of your industrial automation systems, ensuring that your operations run smoothly and safely.

Frequently Asked Questions

What is the voltage rating for this safety relay?

The safety relay operates at a control supply voltage of 24 V DC.

Can this safety relay be used in any mounting position?

Yes, the safety relay is designed for flexible installation and can be mounted in any position.

What type of connections does this safety relay support?

It supports screw-type terminals for secure and reliable electrical connections.

What is the width of the safety relay?

The safety relay has a width of 22.5 mm, making it suitable for compact installation spaces.

Is this safety relay suitable for emergency stop functions?

Yes, the safety relay is designed for emergency stop functions, ensuring safe and reliable operation in critical situations.

What is the maximum installation altitude for this safety relay?

The safety relay can be installed at a maximum altitude of 2,000 meters above sea level.

What is the ambient temperature range for operating this safety relay?

The safety relay can operate within an ambient temperature range of -25 to +60 degrees Celsius.

Does this safety relay have a protection class rating?

Yes, the housing of the safety relay has a protection class rating of IP40, and the terminal has a rating of IP20.

What is the Safety Integrity Level (SIL) of this safety relay?

This safety relay has a Safety Integrity Level (SIL) of 3, according to IEC 61508.

Can this safety relay be used for monitoring light barriers?

Yes, it is suitable for light barrier monitoring applications.

What is the Performance Level (PL) rating of this safety relay?

The safety relay has a Performance Level (PL) rating of 'e' according to EN ISO 13849-1.

Is this safety relay suitable for use in residential environments?

This product is suitable for Class A environments only and may cause radio-frequency interference in residential environments, which may require the user to take appropriate measures.