Siemens 6SL3351-6GH35-8AB3 AC Drive Power Module – SINAMICS S120

Siemens 6SL3351-6GH35-8AB3 — Booksize Power Module in the SINAMICS S120 Multi-Axis Drive Architecture

The 6SL3351-6GH35-8AB3 is a Booksize-format Power Module within the Siemens SINAMICS S120 modular drive system, rated at 55 kW continuous output power with a 105 A continuous output current at a 3-phase AC supply of 380–480 V (±10%). Unlike standalone inverter drives, this module operates exclusively within the S120 shared DC-bus architecture: it draws regulated DC voltage from a Line Module (Active, Smart, or Basic) and converts it to a variable-frequency, variable-voltage AC output for a single motor axis. This structural dependency is not a limitation — it is the design basis that enables deterministic multi-axis synchronization with sub-millisecond torque response across an entire machine cell.

In servo and vector-controlled applications — CNC spindle drives, multi-axis winding machines, high-speed packaging lines — the 6SL3351-6GH35-8AB3 functions as the final power-conversion stage in a closed-loop control chain. The Control Unit (CU320-2 or CU310-2) executes the speed and torque algorithms; the Power Module executes the switching commands at IGBT level. Communication between these two layers travels exclusively over DRIVE-CLiQ, Siemens’ proprietary serial interface that carries both control data and electronic nameplate information at a cycle time synchronized to the drive’s servo sampling period (typically 125 µs for current control, 250 µs for speed control).

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Technical Parameters

Hardware Logical Analysis

The 6SL3351-6GH35-8AB3 employs a three-phase IGBT bridge topology with a gate-drive circuit that operates at a base switching frequency of 2 kHz, selectable up to 8 kHz with proportional current derating. At 2 kHz, the module delivers full 105 A continuous current; at 4 kHz, the thermal derating curve reduces continuous current to approximately 88 A, which remains adequate for most servo spindle applications where the duty cycle includes periodic low-load intervals.

EMC Architecture: The module’s internal layout separates the high-dV/dt IGBT switching section from the DRIVE-CLiQ signal board using a grounded copper shield plane. Common-mode chokes on the DC bus input rails suppress conducted emissions in the 150 kHz–30 MHz band. The chassis bonding point (PE terminal) is rated for high-frequency bonding per IEC 61800-3, Category C2, which means the module can be installed in industrial environments without an additional external EMC filter when the motor cable length is kept below 25 m with shielded cable.

Thermal Management: The power stage heatsink is extruded aluminum with a forced-air channel running the full height of the Booksize form factor. An NTC thermistor embedded in the heatsink feeds a real-time temperature value to the Control Unit via DRIVE-CLiQ. If heatsink temperature exceeds 80 °C, the drive autonomously reduces switching frequency by one step; at 85 °C, output current is derated linearly. This two-stage thermal protection prevents nuisance trips while maintaining production continuity.

Integrated Safety Logic (AB3 Suffix): The AB3 hardware revision integrates a dual-channel safety processor on the power module board itself, enabling STO (Safe Torque Off), SS1 (Safe Stop 1), and SBC (Safe Brake Control) without an external TM54F terminal module. The safety channels are cross-monitored at a 4 ms diagnostic cycle. Discrepancy detection between the two channels triggers a safe state within one monitoring cycle, meeting IEC 62061 SIL 2 and ISO 13849-1 PLd requirements. This architecture reduces wiring complexity in safety-rated machine cells and eliminates the latency introduced by external safety relays.

DC Bus Capacitor Bank: The intermediate DC circuit capacitors are film-type (not electrolytic), selected for a rated ripple current that matches the 105 A output stage. Film capacitors exhibit significantly lower ESR than electrolytic types, which reduces internal heating under high-ripple conditions typical of regenerative braking cycles. This design choice extends capacitor service life beyond 100,000 hours at rated operating temperature.

System Integration Benefits

• Shared DC Bus Energy Recovery: When one axis decelerates, regenerated energy flows back into the common DC bus and is immediately available to an accelerating axis on the same bus segment, reducing peak demand on the Line Module by up to 30% in coordinated multi-axis profiles.
• Automatic Electronic Nameplate via DRIVE-CLiQ: On power-up, the module transmits its rated parameters, firmware version, and serial number to the Control Unit. The CU automatically populates the drive dataset, eliminating manual parameter entry errors during commissioning or module replacement.
• Deterministic Servo Sampling: Current control executes at 125 µs, speed control at 250 µs, and position control at 500 µs — all synchronized across axes via the DRIVE-CLiQ isochronous clock. This determinism is the prerequisite for electronic gearing and cam-profile synchronization in multi-axis machines.
• Integrated Diagnostic Transparency: The module continuously reports DC bus voltage, output current (per phase), heatsink temperature, IGBT junction temperature estimate, and fan speed to the Control Unit. All values are accessible via PROFIBUS/PROFINET process data or STARTER/Startdrive parameter r-values without additional instrumentation.
• Scalable Safety Without External Hardware: STO activation via the onboard dual-channel input removes torque within 10 ms, satisfying Category 3 stop requirements. No external safety relay or contactor is required in the motor circuit, reducing panel component count and potential failure points.
• Firmware-Selectable Control Modes: A single hardware unit supports V/f open-loop, sensorless vector (SLVC), closed-loop vector with encoder, and servo control modes. Mode selection is a parameter change in STARTER or TIA Portal Startdrive — no hardware modification required. This flexibility allows the same module to drive both induction motors and permanent-magnet servo motors within the same machine.
• Booksize Mechanical Standardization: All Booksize Power Modules share identical mounting rail pitch and DC bus bar connector positions. Replacing a failed module requires disconnecting four connectors (DC bus, motor output, DRIVE-CLiQ ×2, 24 V auxiliary) and sliding the unit off the mounting rail — a procedure achievable in under 15 minutes with no special tooling, minimizing unplanned downtime.
• Compatibility with TIA Portal Startdrive: Full parameter access, drive wizard commissioning, trace/oscilloscope function, and safety commissioning are available natively within TIA Portal V14 and later. No separate engineering tool license is required beyond the standard Startdrive package, reducing total software cost for multi-drive projects.

Quality Assurance & Global Logistics

Every 6SL3351-6GH35-8AB3 unit supplied by siemensplc.com is sourced through verified Siemens-authorized distribution channels. Each unit carries a traceable Siemens factory serial number, date code, and country-of-origin marking (Germany). Before dispatch, units undergo a visual inspection checklist covering connector integrity, label authenticity, and packaging seal condition. Pre-shipment functional power-on testing is available on request for critical replacement orders.

Shipments originate from our warehouse in Xiamen, China, with same-day or next-business-day dispatch for in-stock orders confirmed before 14:00 CST. Export documentation — commercial invoice, packing list, and certificate of origin — is prepared to comply with customs requirements in the EU, USA, Southeast Asia, and the Middle East. Preferred carriers include DHL Express, FedEx International Priority, and UPS Worldwide Express, with typical transit times of 3–5 business days to major industrial hubs. For time-critical plant shutdowns, air freight with door-to-door tracking is arranged on request. All shipments are insured at declared value. A 12-month warranty covers manufacturing defects; warranty claims are processed with a target replacement dispatch within 48 hours of fault confirmation.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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