Siemens 6SL3352-6TG37-4AA3 S120 Active Line Module Upgrade

Product Overview

Siemens 6SL3352-6TG37-4AA3 S120 Active Line Module Upgrade: Seamless Transition from Legacy Drive Systems

The Siemens 6SL3352-6TG37-4AA3 is a high-power Active Line Module (ALM) within the SINAMICS S120 drive platform, rated at 750 kW with liquid cooling. Designed for demanding industrial applications — including steel mills, paper machines, large compressors, and heavy-duty conveyor systems — this module provides sinusoidal line currents, active front-end regeneration, and full compliance with harmonic distortion standards. For facilities operating legacy Siemens SIMOVERT MASTERDRIVES, SINAMICS S150, or earlier S120 booksize/chassis configurations, migrating to the 6SL3352-6TG37-4AA3 represents a technically sound and commercially viable modernization path.

When planning a retrofit or replacement, engineers frequently encounter the challenge of integrating a new Active Line Module into an existing control cabinet without full system redesign. The 6SL3352-6TG37-4AA3 is engineered to address this directly. Its liquid-cooling interface is compatible with standard Siemens cooling plate assemblies used across the S120 chassis family, reducing the need for cabinet modifications. The DC bus connection architecture aligns with existing Motor Modules such as the 6SL3320-series Single Motor Modules and 6SL3321-series Double Motor Modules, allowing the ALM to be integrated into multi-axis drive lines without rewiring the intermediate DC link.

From a communications standpoint, the module interfaces natively with the SINAMICS S120 Control Unit — typically a CU320-2 DP or CU320-2 PN — via DRIVE-CLiQ. This eliminates the protocol conversion overhead that often complicates migrations from older fieldbus-based systems. Sites previously running PROFIBUS DP with a CBE20 communication board can retain their existing PLC topology while upgrading the power stage, since the CU320-2 PN supports both PROFINET and legacy PROFIBUS configurations through appropriate option boards.

Wiring compatibility is a critical concern during any high-power drive replacement. The 6SL3352-6TG37-4AA3 uses the same line-side terminal block geometry as other S120 chassis-format Active Line Modules, meaning existing cable lugs, busbar connections, and PE bonding points can typically be reused. The liquid cooling inlet/outlet fittings conform to Siemens standard hose connector specifications, so existing coolant distribution manifolds do not require replacement. This significantly reduces installation labor and commissioning time — a key factor when minimizing production downtime during planned maintenance windows.

For sites that previously relied on a Basic Line Module (BLM) such as the 6SL3352-series or a Smart Line Module (SLM) in the 6SL3330-series, upgrading to the 6SL3352-6TG37-4AA3 Active Line Module unlocks regenerative braking capability and active harmonic compensation. This is particularly valuable in applications with high-inertia loads where energy recovery during deceleration can meaningfully reduce operating costs. The transition requires updating the drive parameterization in STARTER or Startdrive software, but the physical installation footprint and cabinet space requirements remain consistent with the existing chassis slot allocation.

Power supply compatibility should be verified during pre-commissioning. The 6SL3352-6TG37-4AA3 operates on a 3-phase AC supply in the 380–480 V range, consistent with standard industrial grid voltages across Europe and Asia. The internal 24 V DC logic supply is derived from the line voltage via the integrated power supply, so no separate SITOP PSU600 or external 24 V rail is required for the module itself — though the CU320-2 and associated I/O modules on the same rack will still require their own 24 V supply from a dedicated power supply unit.

During system commissioning, the ALM must be parameterized in conjunction with the associated Line Module Reactors (e.g., 6SL3000-series line reactors) and, where applicable, the Active Interface Module (AIM) in the 6SL3300-series. These upstream components are essential for harmonic filtering and must be sized to match the 750 kW rating of the ALM. Existing installations that already include correctly rated line reactors from a prior S120 system can typically retain these components, further reducing the scope and cost of the upgrade.

For multi-drive architectures, the 6SL3352-6TG37-4AA3 can supply DC bus power to multiple Motor Modules mounted on the same chassis rack or connected via a shared DC bus bar. This topology is common in coordinated multi-axis applications such as winding machines, extruders, and rolling mills, where a single ALM feeds several axes simultaneously. The module’s internal diagnostics and fault reporting are fully integrated into the SINAMICS S120 fault management system, accessible via the CU320-2 operator panel or through PROFINET/PROFIBUS to the supervisory PLC — typically a SIMATIC S7-400H or S7-1500 series controller.

Spare parts and inventory planning are simplified by the modular architecture of the S120 platform. The 6SL3352-6TG37-4AA3 can be held as a critical spare alongside complementary components such as the DRIVE-CLiQ hub module DMC20 or DME20, Sensor Modules for encoder feedback, and the Braking Module in the 6SL3300-series for applications requiring dynamic braking. Stocking these components as a coordinated spare set ensures rapid recovery from unplanned failures without extended lead times.

Compatibility Comparison Table

Seamless Upgrade Solutions

A complete migration to the 6SL3352-6TG37-4AA3 typically involves coordinating several interdependent components within the same S120 system architecture. The CU320-2 PN Control Unit serves as the central intelligence of the drive system, managing parameterization, fault diagnostics, and fieldbus communication for the ALM and all connected Motor Modules. Where multi-axis coordination is required, the DRIVE-CLiQ hub module DMC20 provides the necessary topology expansion, connecting multiple DRIVE-CLiQ devices — including Sensor Modules SMC20 or SMC30 for encoder feedback — to a single CU320-2 port.

On the line side, the 6SL3000-series Line Module Reactor must be correctly rated for 750 kW to ensure harmonic compliance and protect the ALM input stage. For installations requiring additional harmonic attenuation, the Active Interface Module (AIM) in the 6SL3300-series can be installed upstream of the ALM. The 24 V DC supply for the CU320-2 and associated I/O modules is typically provided by a SITOP PSU600 series power supply, which should be verified for adequate current capacity when adding new modules to an existing rack.

Motor Modules such as the 6SL3320-series Single Motor Module or 6SL3321-series Double Motor Module connect to the shared DC bus supplied by the 6SL3352-6TG37-4AA3, enabling coordinated multi-axis drive control within a single cabinet. For applications requiring dynamic braking on individual axes, the Braking Module in the 6SL3300-series can be added to the DC bus without modifying the ALM configuration. Signal isolation between the drive system and field instrumentation is handled by dedicated signal isolators or terminal modules from the SIMATIC ET 200SP or ET 200M families, which interface directly with the S7-1500 or S7-400 PLC supervising the overall process.

Retrofit Guidance FAQ

Q: Can I reuse existing wiring when replacing an older S120 ALM with the 6SL3352-6TG37-4AA3?
A: In most cases, yes. The chassis-format terminal geometry and DC bus busbar connections are consistent across the S120 chassis ALM family. Line-side cable lugs and PE bonding points are typically reusable. Verify cable cross-section ratings against the 750 kW input current specification before reuse.

Q: Is the existing CU320-2 Control Unit compatible?
A: Yes. Both CU320-2 DP and CU320-2 PN variants are fully compatible. The ALM connects via DRIVE-CLiQ and is automatically recognized during the topology scan in STARTER or Startdrive. Firmware version alignment between the CU320-2 and the ALM should be confirmed prior to commissioning.

Q: What changes are required in the drive program (STARTER/Startdrive)?
A: The ALM must be re-parameterized to reflect the 750 kW rating, cooling type, and line conditions. If upgrading from a BLM or SLM, the control mode must be changed to Active Line Module operation and the regenerative energy recovery parameters enabled. Existing Motor Module parameterization is unaffected.

Q: Does the liquid cooling interface require cabinet modifications?
A: The liquid cooling inlet/outlet fittings conform to Siemens standard specifications used across the S120 chassis liquid-cooled range. Existing coolant distribution manifolds and hose assemblies are typically compatible. Coolant flow rate and temperature specifications should be verified against the 750 kW thermal load.

Q: How is PROFIBUS DP communication maintained after the upgrade?
A: The CU320-2 DP natively supports PROFIBUS DP. If using a CU320-2 PN, the CBE20 communication board enables PROFIBUS DP operation alongside PROFINET. No changes to the upstream SIMATIC S7 PLC program are required if the drive object addressing is preserved.

Q: What is the physical installation space requirement?
A: The 6SL3352-6TG37-4AA3 occupies a standard S120 chassis slot. Cabinet depth and width requirements are consistent with other chassis-format ALMs in the S120 range. Confirm the cabinet cooling circuit capacity supports the liquid-cooled module’s thermal dissipation requirements.

Warranty Assurance

Every 6SL3352-6TG37-4AA3 unit supplied by TOPNLMS is covered by a 12-month warranty from the date of shipment. Prior to dispatch, each unit undergoes functional verification including power-on testing, DRIVE-CLiQ interface check, and visual inspection of cooling ports, terminal blocks, and firmware version confirmation. Units are packaged in anti-static, shock-resistant materials suitable for international freight.

In the event of a confirmed fault within the warranty period, TOPNLMS provides replacement unit dispatch or repair support with priority handling. Our technical team is available to assist with pre-installation compatibility verification, commissioning parameter guidance, and post-installation fault diagnosis. Response to warranty claims is initiated within 1 business day of fault report submission.

For procurement teams managing critical spare inventories, TOPNLMS maintains stock of high-demand S120 components to support rapid fulfillment. Lead times, stock availability, and volume pricing are available upon request. All units are sourced through verified supply channels and are accompanied by documentation supporting traceability requirements.

Contact our technical sales team to confirm compatibility with your existing system configuration before placing an order.