Siemens 6SL3130-7TE21-6AA3 ALM Active Power Module (Book-Style)

The Siemens 6SL3130-7TE21-6AA3 is an Active Line Module (ALM) from the renowned SINAMICS S120 drive system. This 16kW, booksize-formatted power supply module is more than a simple rectifier—it is a high-precision, regenerative power converter that serves as the intelligent electrical core of sophisticated multi-axis automation systems.

It provides a stable, regulated DC bus voltage while enabling energy recovery to the grid, delivering unparalleled performance and efficiency for applications ranging from high-dynamic machine tools to precision packaging systems. Below is a detailed examination of this ALM model, plus insights into the broader role and selection criteria of power modules in industrial automation.

Product Core: Technical Specifications and Functional Anatomy

At its core, the 6SL3130-7TE21-6AA3 converts three-phase AC power into a precisely regulated DC bus voltage to supply downstream motor modules.

 Key Technical Data

Article Number: 6SL3130-7TE21-6AA3

Product Type: SINAMICS S120 Active Line Module (ALM)

Input Voltage: 3 AC 380–480 V, 50/60 Hz

Output Power: 16 kW

Output DC Current: 27 A

Regulated DC Link Voltage: 600 V DC

Cooling Method: Internal air cooling

Design: Booksize

Communication: Integrated DRIVE-CLiQ interface

Key Features and Components

IGBT-Based Active Rectification: Unlike basic diode bridges, it uses IGBTs (Insulated-Gate Bipolar Transistors) for bidirectional power flow. This lets it act as a rectifier during motor motoring and an inverter to feed energy back to the grid during motor braking.

Stable DC Link Voltage: Maintains a constant DC bus voltage (e.g., 600V) regardless of mains supply fluctuations. This decouples motor voltage from supply voltage, ensuring consistent performance for all connected drives.

Integrated System Connectivity: Fully integrated into the S120 ecosystem via DRIVE-CLiQ. This digital interface enables automatic configuration, comprehensive diagnostics, and real-time data exchange with the controlling CU (Control Unit).

Comprehensive Safety and Shielding: Includes interfaces for connecting cable shields (power and signal cables) to support proper EMC practices. It also features integrated safety functions (e.g., safe torque off/STO via dedicated terminals).

Performance Advantages: Why Choose This ALM?

The 6SL3130-7TE21-6AA3’s technological design translates to critical on-site benefits:

Exceptional Power Quality: Produces a nearly sinusoidal input current, resulting in a high power factor (cos φ ≈ 1). This minimizes reactive power and harmonic distortion in the supply network, often eliminating the need for external power factor correction units and avoiding utility penalties.

Energy Efficiency and Cost Savings: Regenerates braking energy directly back to the plant’s electrical grid, reducing energy consumption and heat generation. This is especially valuable for applications with frequent start-stop cycles or high inertial loads, cutting operational costs and lowering carbon footprint.

Maximized Process Quality and Uptime: The stable DC bus voltage ensures motor modules deliver full torque even at low speeds—unaffected by line voltage sags. This is critical for high-precision machining, synchronized motion, and process stability, reducing production defects and unplanned downtime.

 Integration and Typical Applications

This module is typically controlled by a central unit (e.g., CU320-2) or integrated into a SIMATIC/SINUMERIK automation environment. It is a cornerstone of the SINAMICS S120 “Common DC Bus” architecture, where one ALM can supply multiple motor modules (servo or vector control) on the same DC bus.

Prime Application Areas

Machine Tools: CNC machining centers, lathes, and grinders requiring high dynamic response and precision.

Packaging Machinery: Robots and servo-driven axes in filling, palletizing, and wrapping machines.

Material Handling: High-speed gantry robots, automated storage and retrieval systems (AS/RS).

Test Benches: Simulators and dynamometers needing motoring and regeneration capabilities.

Beyond the Model: Understanding Power Modules in Industrial Automation

To make informed decisions, it’s essential to contextualize the Active Line Module within Siemens’ power module lineup and clarify key system design considerations.

The Power Module Spectrum: ALM vs. SLM vs. BLM

SINAMICS S120 offers three core power module types, each tailored to different performance and cost needs:

1.1 Active Line Module (ALM)

DC Link Voltage: Regulated (e.g., 600V)

Energy Feedback: Yes (regenerative)

Technology: IGBT-based active front end

Input Power Factor: ~1 (excellent)

Typical Use Case: High-precision, dynamic, energy-saving applications (e.g., CNC machines, high-speed robots).

1.2 Smart Line Module (SLM)

DC Link Voltage: Non-regulated (~1.35 x input voltage)

Energy Feedback: Yes (regenerative)

Technology: IGBT-based

Input Power Factor: >0.96 (very good)

Typical Use Case: Applications needing energy recovery but tolerating fluctuating DC link voltage (e.g., some packaging machines).

1.3 Basic Line Module (BLM)

DC Link Voltage: Non-regulated (~1.35 x input voltage)

Energy Feedback: No (non-regenerative)

Technology: Diode/thyristor-based

Input Power Factor: Dependent on line reactor

Typical Use Case: Cost-sensitive applications with infrequent braking (e.g., pumps, fans). A braking resistor is required to dissipate braking energy.

1.4 How to Choose

Select ALM: When you need stable DC link voltage, excellent power quality, and maximum energy recovery (critical for precision or dynamic tasks).

Select SLM: When energy recovery is key, but fluctuating DC link voltage is acceptable (balances performance and cost).

Select BLM: For simple, budget-focused applications with minimal braking (no energy recovery needed).

2. Critical Considerations for System Design

Integrating an ALM requires attention to three key details:

Mandatory Active Interface Module (AIM): An AIM must be installed between the grid and ALM. It integrates a line filter, pre-charging circuit, and line voltage monitoring—essential for EMC compliance and safe operation.

Cooling and Space: The booksize design allows compact, side-by-side mounting in control cabinets. Ensure adequate airflow and compliance with the ambient temperature range (0–40°C without derating) to avoid overheating.

System Configuration: The entire drive system (ALM, motor modules, motors) is configured via Siemens’ SINAMICS Startdrive software (within TIA Portal), ensuring seamless integration.

Frequently Asked Questions (FAQs)

1. How does an ALM save energy compared to a basic power supply?

An ALM regenerates braking energy: during braking, motors act as generators. Basic modules (BLM) waste this energy as heat via resistors, but ALMs invert it back to the grid. This recycled energy powers other equipment, cutting total electricity use—especially for frequent start-stop applications.

2. Is the regulated DC voltage from an ALM really important?

Yes, for high-performance tasks. A stable DC bus ensures motor modules deliver full torque across all speeds, unaffected by mains fluctuations or heavy loads. This prevents performance issues during voltage sags, critical for precision machining or synchronized motion.

3. My application doesn’t brake frequently. Do I still need an ALM?

If energy savings aren’t key, focus on other ALM benefits: rock-solid DC bus voltage (for process stability) and near-perfect power factor (protects electrical systems from harmonics). If these don’t matter, an SLM or BLM is more cost-effective.

4. What key component must I add to use this ALM?

You need an Active Interface Module (AIM) between mains power and ALM. It’s not optional—it provides the line filter and pre-charging circuit needed for safe, EMC-compliant operation.

5. Can this 16kW ALM power mixed motor modules?

Yes, via the Common DC Bus. The ALM supplies 16kW of continuous power; you can connect any combination of S120 motor modules (e.g., 10kW + two 3kW) as long as total demand doesn’t exceed 16kW (accounting for peak loads).

6. What are the key ALM maintenance points?

Focus on prevention: keep cooling fins/fans clean (avoid overheating), check power connection tightness during downtime, and use DRIVE-CLiQ diagnostics to track operating hours, temperatures, and faults for predictive maintenance.