SINAMICS S120 Auxiliary Modules: Filters, Brake Resistors & More

The Siemens SINAMICS S120 modular drive system is designed for flexibility, and one of the key ways it achieves this is through the use of auxiliary modules. These add-on components go beyond the main control, motor, and line modules to provide enhanced performance, improved safety, and better system longevity. Whether you need to control electromagnetic interference, dissipate excess energy, keep components cool, or maintain power during an outage, auxiliary modules offer solutions tailored to your application.

The Role of Auxiliary Modules

Auxiliary modules act as supporting elements for your SINAMICS S120 system, addressing specialized needs that the main drive components don’t handle alone. By integrating the right auxiliary modules, you can protect sensitive electronics, maintain consistent performance under demanding loads, and extend the life of your system. While not every application requires all types of auxiliary modules, many benefit from at least one or two key add-ons.

Filter Modules – EMI Suppression

Electromagnetic interference (EMI) can be a serious issue in industrial environments, affecting nearby equipment and communication systems. SINAMICS S120 filter modules help ensure compliance with EMC regulations while keeping signal noise under control. These modules are installed between the line module and the power supply, reducing harmonics and minimizing interference.

Popular filter module part numbers include 6SL3000-0CE31-6AA0 and 6SL3000-0CE31-8AA0, which are designed for different power ratings. Choosing the correct filter module depends on your system’s voltage, current draw, and the EMC class you need to meet.

Brake Resistors – Energy Dissipation

When a motor decelerates quickly, it converts kinetic energy back into electrical energy. If this regenerated energy is not fed back to the supply (via a regenerative line module), it must be dissipated to prevent damage to the drive. Brake resistor modules convert this excess energy into heat safely, allowing for fast stops without overloading the system.

Typical brake resistor module part numbers include 6SL3000-0BE31-8AA0 and 6SL3000-0BE31-2AA0. The correct selection depends on braking cycles, load inertia, and thermal limits.

Fan Modules – Cooling Solutions

Heat is one of the biggest threats to drive longevity. Fan modules provide targeted cooling for high-power applications or enclosed cabinets with limited airflow. They help maintain optimal operating temperatures, which reduces the risk of thermal shutdowns and extends component life.

While some SINAMICS modules have built-in fans, external fan modules like the 6SL3000-0CE31-2AA0 can boost cooling capacity for particularly demanding environments.

Power Supply Modules – Backup and Redundancy

In critical applications, a brief loss of control power can cause major disruptions. SINAMICS power supply modules provide backup power for control electronics, enabling safe system shutdowns or maintaining logic functions during brief outages. They can also supply power to peripheral devices, ensuring continuous communication and control.

Examples include the 6SL3055-0AA00-3AA0, which provides a stable 24V supply to SINAMICS components and connected sensors.

Choosing the Right Add-Ons

Selecting auxiliary modules isn’t just about adding features — it’s about matching your operational needs. Consider:

• Application demands: High-speed deceleration may require brake resistors, while sensitive environments may need EMI filters.
• Environmental factors: Hot or dusty environments may benefit from additional fan modules.
• Safety requirements: Some applications mandate backup power for safe stop functionality.
• System configuration: Ensure compatibility with your control, motor, and line modules.

Maintenance and Longevity

Like all components, auxiliary modules benefit from regular inspection. Check filter modules for dust buildup, verify brake resistor connections, and confirm fan operation to avoid overheating. For power supply modules, ensure cables are secure and capacitors are within operating specifications. Preventive care will keep your SINAMICS S120 running reliably and avoid costly downtime.

Final Thoughts

Auxiliary modules are the unsung heroes of the SINAMICS S120 drive system, adding layers of protection, performance, and safety that can make the difference between an average setup and a high-reliability installation. By selecting the right combination — whether it’s filters, brake resistors, fans, or backup power — you can ensure your system performs at its best for years to come.

Contact Industrial Automation Co. today for help selecting, sourcing, or replacing SINAMICS S120 auxiliary modules to fit your exact needs.