SINAMICS S120 Modular Drive System Delivers High-Performance Motion Control with Unmatched Scalability

A Flexible Platform for Demanding Single-Axis and Multi‑Axis Applications

The SINAMICS S120 drive system from Siemens offers a modular, scalable solution for challenging motion control tasks in machine and plant engineering, covering 0.12 kW to 4,500 kW. It handles simple single‑axis and complex multi‑axis configurations equally well. The architecture separates control intelligence from power electronics, letting users select the Control Unit based on axis count and performance, while choosing Power, Line, or Motor Modules to match energy demands. This answers the “what” and “how” of modern drive design – whether for a packaging machine with six servo axes requiring microsecond‑synchronous positioning, or a paper mill needing vector‑controlled drives for continuous webs. The system supports Servo control for highly dynamic cyclic processes with synchronous motors, Vector control for rugged asynchronous motor applications, and V/f control for simpler group drives. Engineers freely combine formats – booksize for space‑efficient multi‑axis cabinets, blocksize for standalone single‑axis units, and chassis for high‑power outputs above 100 kW – all linked via the digital DRIVE‑CLiQ interface, which auto‑detects components via electronic rating plates and eliminates manual parameter entry. BICO technology allows free interconnection of internal signals for custom logic. This flexibility adapts seamlessly to both distributed and centralized automation structures.

Intelligent Control Units and Engineering Tools for Efficient Commissioning

The intelligence of SINAMICS S120 resides in its Control Units, selected by axis count and complexity. For single axes, the CU310 DP (PROFIBUS) and CU310 PN (PROFINET) offer compact control with integrated encoder evaluation and onboard I/O. For multi‑axis systems, the CU320‑2 manages up to six servo or four vector axes, handling speed, torque, and positioning while coordinating inter‑axis data internally – eliminating fieldbus communication between drives. For advanced motion control with electronic gearing and cam disks, SIMOTION D units (D425, D435, D445) integrate the motion controller on the drive, supporting up to 64 axes and reducing cabinet space. All Control Units store firmware and parameters on a removable CompactFlash card for rapid replacement without software tools. The STARTER commissioning software guides first startup with wizards, while the integrated trace function records up to four signals for optimization. The Drive ES engineering system enables parameterization within STEP 7 for consistent data management. PROFIdrive V4 ensures interoperability with PROFIBUS or PROFINET masters, supporting categories from simple speed control to dynamic servo with isochronous real‑time communication. With PROFINET IO and IRT, cycle times reach 125 µs with jitter below 1 µs, meeting strict real‑time demands for high‑speed printing and machining. These engineering tools, combined with hardware scalability, let integrators design and maintain drive solutions efficiently.

Comprehensive Power Components and Integrated Safety Functions

The power section of SINAMICS S120 includes Line Modules (Basic, Smart, and Active) that supply the DC link, and Motor Modules that convert DC to variable AC for motors. Basic Line Modules are non‑regenerative units for applications without energy feedback, while Smart Line Modules offer regenerative capability up to 100% for energy recovery during braking, and Active Line Modules provide a regulated DC link voltage that remains constant despite line fluctuations, drawing nearly sinusoidal current to limit harmonics. For single‑axis drives, Power Modules integrate rectifier and inverter in one unit, available with or without integrated line filters for EMC compliance. The system includes DC link components such as Braking Modules and braking resistors for controlled deceleration during power failure, Capacitor Modules to bridge momentary voltage dips, and Voltage Clamping Modules to dampen oscillations with long motor cables. Integrated safety functions – Safe Torque Off (STO) and Safe Brake Control (SBC) – are certified to SIL 2 and control category 3, enabling safe standstill and brake monitoring without external safety relays. The DRIVE‑CLiQ interface connects motors with built‑in encoders and electronic rating plates, simplifying commissioning through automatic motor and encoder identification. For motors without DRIVE‑CLiQ, Sensor Modules (SMC10 for resolvers, SMC20 for sin/cos encoders, SMC30 for TTL/HTL) convert signals to DRIVE‑CLiQ. This comprehensive power portfolio, combined with safety functions and flexible motor connectivity, makes SINAMICS S120 suitable for applications from compact servo drives to large multi‑megawatt installations.

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