SINAMICS S120 Motor Modules – Precision Motion Control at Every Axis

In the Siemens SINAMICS S120 modular drive system, motor modules convert the DC link voltage from the line module into variable-frequency AC for your motors. They’re responsible for speed, torque, and position accuracy on each axis. Separating power conversion (motor module) from system control (control unit) and power infeed (line module) enables highly scalable, multi-axis systems that are easy to tailor to your machine.

Single vs. Double-Axis Motor Modules

• Single-axis modules – One motor per module; higher peak power per axis; common for larger motors or high-torque applications.
• Double-axis modules – Two independent motors in one unit; saves cabinet space and cost in multi-axis systems with smaller loads.

How to choose: base it on load requirements, available panel space, and total cost. Many lines mix both to balance performance and footprint.

Performance Features

• High torque accuracy for consistent product quality (e.g., printing, packaging).
• Fast dynamic response for robotics, pick-and-place, and high-speed motion.
• Precise positioning with high-resolution encoders for micron-level control.
• Shared DC bus allows energy from one axis to be reused by others before returning to the mains.

Sizing & Selection – Match the Load

1. Motor type – Induction, synchronous, or servo.
2. Current ratings – Match continuous and peak current to the motor’s demands.
3. Cooling method – Air-cooled for most cabinets; liquid-cooled for high-density or sealed enclosures.
4. Format – Booksize for compact multi-axis; chassis for higher-power single-axis.
5. Axis count – Choose single vs. double-axis to optimize cost and space.

Popular Models

• 6SL3120 series – Single-axis booksize modules for high-performance servo control.
• 6SL3121 series – Double-axis booksize modules for space-efficient multi-axis control.
• 6SL3122 series – Chassis format for high-power industrial motors.

Industrial Automation Co. stocks a range of these models to help you avoid long factory lead times.

Maintenance Tips – Prevent Overheating & Trips

• Keep cooling paths clear – Inspect fans and vents for dust and debris.
• Monitor temperatures – Address warnings before they become faults.
• Update firmware – Maintain performance and compatibility.
• Inspect DC bus connections – Tighten during scheduled maintenance.
• Log diagnostics – Review fault history to spot recurring issues early.

Closing

The SINAMICS S120 motor module is the powerhouse of each motion axis. Selecting the correct configuration—single or double-axis—optimizes space, cost, and performance. With proper sizing, proactive maintenance, and access to quality replacements, your S120 system can deliver precise, reliable motion for years.