Siemens 3RT2024-2BB40 Industrial Control Contactor with Auxiliary Contact 24VDC 12A 3NO

The Siemens 3RT2024-2BB40 is a high-performance industrial control contactor designed for demanding applications, offering reliability and efficiency in power switching operations. This 3-pole, normally open (3NO) device features a 24VDC coil voltage and a 12A current rating, making it ideal for motor control, power distribution, and automation systems. Its integrated auxiliary contact simplifies control circuit design, reducing the need for external components. The Siemens 3RT2024-2BB40 stands out with its compact design, robust construction, and excellent electrical properties, ensuring long service life and minimal maintenance.

Product Specifications

| Feature                 | Specification                                |

| :---------------------- | :------------------------------------------- |

| Product Type            | Industrial Control Contactor                 |

| Manufacturer            | Siemens                                      |

| Model Number            | 3RT2024-2BB40                                |

| Pole Configuration      | 3-Pole, Normally Open (3NO)                  |

| Coil Voltage            | 24V DC                                       |

| Rated Operational Current | 12A (AC-3, 400V)                             |

| Auxiliary Contacts      | 1 Normally Open (1NO)                        |

| Terminal Type           | Spring-loaded terminals                      |

| Mounting                | DIN rail or screw mounting                   |

| Ambient Temperature     | -25 to +60 °C                                |

| Protection Rating       | IP20                                         |

| Standards Compliance    | IEC 60947-4-1, IEC 60947-5-1, UL, CSA        |

Core Features & Market Positioning

The Siemens 3RT2024-2BB40 distinguishes itself through its advanced spring-loaded terminal technology, which ensures reliable connections even under vibration, a common issue in industrial environments. This feature simplifies wiring and reduces installation time, a critical factor in complex control panels. Its robust design adheres to stringent IEC and UL standards, positioning it as a dependable choice for safety-critical applications. The integrated auxiliary contact further enhances its value by streamlining control logic and reducing the overall component count in a control panel, contributing to a more compact and cost-effective solution.

Key Application Scenarios

This Siemens 3RT2024-2BB40 industrial control contactor is exceptionally well-suited for controlling small to medium-sized three-phase motors in various industrial sectors, including manufacturing, material handling, and HVAC systems. Its 24VDC coil voltage makes it compatible with standard control power supplies and Programmable Logic Controllers (PLCs), facilitating seamless integration into automated processes. The 12A rating is appropriate for pumps, fans, compressors, and other machinery requiring reliable switching. Additionally, its compact size and direct mounting options are ideal for applications where space is limited, such as in control cabinets for building automation or specialized industrial machinery.

Practical System Integration Guidance

Integrating the Siemens 3RT2024-2BB40 is straightforward due to its user-friendly design. The spring-loaded terminals accept solid and flexible conductors without requiring special tools, ensuring a secure connection. For wiring the control circuit, connect the 24VDC power supply to the coil terminals (A1 and A2, typically), observing polarity. The integrated auxiliary contact (usually labeled 13NO/14NC or similar) can be wired into the control logic for interlocking, signaling, or feedback purposes. Ensure the ambient temperature remains within the specified operating range (-25 to +60 °C) to guarantee optimal performance and longevity.

Operation and Risk Mitigation

Proper operation of the Siemens 3RT2024-2BB40 involves ensuring the coil voltage is consistently within the 24VDC specification to prevent premature failure or erratic switching. Overloading the contactor beyond its 12A rating (AC-3) can lead to overheating, contact welding, and eventual failure, posing a significant safety risk. Always install fuses or circuit breakers appropriately sized to protect the contactor and the load. In case of failure to switch or erratic behavior, check the coil voltage supply and verify the absence of mechanical obstructions. Regular visual inspection for signs of excessive heat or wear can help mitigate potential risks and ensure safe operation.

Scalability & Long-Term Value

The Siemens 3RT2024-2BB40 is part of Siemens' comprehensive Sirius modular system, offering excellent scalability. Its compatibility with other Sirius components, such as overload relays and motor protection circuit breakers, allows for the creation of fully integrated motor control solutions. This ensures that as system requirements evolve, the contactor can be easily incorporated into larger, more complex configurations. For facilities embracing Industry 4.0 initiatives, Siemens offers communication modules that can integrate these contactors into digital monitoring and control networks, providing real-time data and enhancing predictive maintenance capabilities, thereby maximizing long-term operational value.

Frequently Asked Questions

What is the primary function of a Siemens 3RT2024-2BB40 contactor?

The Siemens 3RT2024-2BB40 is an industrial control contactor used for switching electrical power to loads. It operates as an electrically controlled switch, often used for starting and stopping motors.

It facilitates remote control and automation of electrical circuits. The 3RT2024-2BB40 is designed for AC-3 motor switching applications.

This contactor is crucial in power distribution and control panels for safely managing electrical loads.

How do I correctly wire the Siemens 3RT2024-2BB40 contactor?

Wire the 24VDC coil to terminals A1 and A2, observing correct polarity for reliable operation. Connect the power circuit through the main terminals (typically 1L1, 3L2, 5L3 for input and 2T1, 4T2, 6T3 for output).

Use the integrated auxiliary contact (e.g., 13NO) for control logic, such as signaling or interlocking. Ensure all connections are secure and follow local electrical codes.

Always refer to the specific wiring diagram provided by Siemens for your application to ensure safe and correct installation.

What are the advantages of using a Siemens 3RT2024-2BB40 over other contactors?

It offers superior reliability with spring-loaded terminals, preventing loose connections due to vibration. The compact design saves valuable panel space.

The integrated auxiliary contact reduces component count and installation complexity. Siemens is known for robust, high-quality industrial components with long service life.

This model complies with international standards, ensuring broad applicability and safety in demanding industrial environments.

Can the Siemens 3RT2024-2BB40 be used for DC loads?

The Siemens 3RT2024-2BB40 is primarily designed and rated for AC-3 motor switching applications. While it has a DC coil, its main contacts are intended for AC circuits.

Using this contactor for DC loads may require specific derating or specialized DC contactors. Consult the Siemens technical documentation for specific DC application guidelines.

For heavy DC loads, it is generally recommended to use contactors specifically designed for DC switching to ensure safety and reliability.

What is the maximum current rating of the Siemens 3RT2024-2BB40?

The Siemens 3RT2024-2BB40 has a rated operational current of 12A when used for AC-3 motor switching applications at 400V.

This rating is critical for selecting the correct contactor for a specific motor or load. Exceeding this rating can cause damage or failure.

Always ensure the load's current draw is within the contactor's specified limits for safe and effective operation.

What is the significance of the 24VDC coil voltage?

A 24VDC coil voltage is common in industrial automation for safety and compatibility. It is typically used with PLC outputs and low-voltage control power supplies.

This voltage level is considered safe for personnel and reduces the risk of electric shock during installation and maintenance. It also allows for easier integration with modern control systems.

Using a 24VDC coil simplifies power distribution within a control panel compared to higher AC voltages.

Does the Siemens 3RT2024-2BB40 include overload protection?

No, the Siemens 3RT2024-2BB40 contactor itself does not include integrated overload protection. It is designed to work in conjunction with separate overload relays or motor protection circuit breakers.

Overload protection is a separate component that must be selected and wired into the circuit to protect the motor and the contactor from overcurrent conditions.

Proper selection and installation of an appropriate overload relay are essential for a complete and safe motor control solution.

What are the dimensions of the Siemens 3RT2024-2BB40?

The Siemens 3RT2024-2BB40 has a compact design, typically measuring around 45mm in width and 90-100mm in height, depending on accessories. Its depth is also standardized for modular mounting.

These dimensions are optimized for space-saving in control cabinets. Exact dimensions can be found in the product's technical datasheet.

The compact form factor allows for higher density of components within a control panel, reducing overall footprint.

What auxiliary contact configuration does the 3RT2024-2BB40 come with?

The Siemens 3RT2024-2BB40 typically comes with one normally open (NO) auxiliary contact. This is indicated by the "-2BB40" part of the model number.

This auxiliary contact can be used for signaling the contactor's state or for interlocking purposes in control circuits. It is a standard feature for basic control feedback.

Additional auxiliary contact blocks can often be mounted on the front or side of the contactor to expand its control capabilities.

What is the IP rating of this contactor, and what does it mean?

The Siemens 3RT2024-2BB40 has an IP20 rating. IP20 signifies protection against solid objects greater than 12.5mm in size (like a finger) and no protection against water ingress.

This rating means the contactor is suitable for indoor use in protected environments where there is no risk of direct contact with hazardous parts or water.

For applications requiring higher protection against dust or moisture, enclosures or contactors with higher IP ratings would be necessary.