SINAMICS S120 Active Line Module: Filter and Reactor Requirements

SINAMICS S120 Active Line Module: Line Filter, Line Reactor, and Active Interface Module Requirements

1. Problem Overview

A SINAMICS S120 Booksize Active Line Module (ALM) such as 6SL3130-7TE21-6AA4 (16 kW, 3-phase 380–480 V) cannot operate reliably when connected to a Basic Line Filter alone. The configuration tooling (SINAMICS SIZER, SCOUT/STARTER, Startdrive) accepts the topology and only flags a warning, but in practice the drive trips with overcurrent faults the moment the IGBT pulses are enabled. This article documents the engineering basis for the requirement, identifies the permissible component combinations, and gives the parameter steps required to commission a valid system including an Active Interface Module (AIM) or HFD line reactor.

2. SINAMICS S120 Booksize Line-Side Component Identification

The S120 Booksize product family separates line-side filtering into four distinct component groups. Each has a unique catalog number and function. The 16 kW class is the most common source of the configuration error described above because the ALM, BLF, and SMM are sold as standalone catalog items rather than as a Combi module.

3. Functional Distinction: Line Reactor vs. Line Filter vs. AIM

Three concepts are repeatedly conflated during Booksize commissioning. Their roles are:

3.1 Line Reactor (HFD or AIM-integrated)

A three-phase iron-core commutation reactor placed in series with the ALM input. The reactor:

• Limits di/dt during IGBT commutation, protecting the IGBT modules from inrush.
• Stores the magnetic energy required for the ALM's voltage step-up function, which boosts the rectified line voltage to a regulated DC-link level above the peak line voltage.
• Works in combination with the damping resistor (or AIM active control) to suppress filter resonance between the BLF capacitance and the line inductance.
• Reduces line-side harmonic distortion (THDi) — typically to 3–5 % at 16 kW class.

3.2 Basic Line Filter (BLF)

A passive L-C RFI filter tuned to meet EN 61800-3 Class A1 conducted emissions limits. It:

• Provides common-mode and differential-mode noise attenuation to ground and between phases.
• Contains no commutation inductance and therefore cannot perform the ALM's voltage step-up function.
• Does not, on its own, limit di/dt or protect the IGBT modules.

3.3 Active Interface Module (AIM)

An integrated module containing the line filter, the HFD reactor, and an IGBT-based damping circuit. The AIM:

• Replaces the discrete reactor + damping resistor with a self-contained, factory-tuned unit.
• Provides active resonance damping between the BLF and the line.
• Is the preferred solution for new installations because it eliminates field tuning of the RC damping network.

For AC drives in general, line reactors and line filters address different problems: reactors limit current harmonics and protect the drive; filters attenuate conducted RF noise. See the Rockwell Automation knowledge base article on line reactor vs. line filter for a vendor-independent summary, and AutomationDirect's line reactor and output filter overview for general sizing guidance.

4. Root Cause: Why an ALM Cannot Operate Without a Line Reactor

The ALM is a self-commutated, voltage-source rectifier using an IGBT bridge with closed-loop DC-link voltage control. Two functions in the control loop physically require inductance at the AC terminals:

1. Voltage step-up. The control loop commands the IGBTs to boost the DC-link voltage above the peak of the rectified line. Without sufficient source inductance, the boost ratio cannot be sustained; the DC voltage collapses to the rectified peak and the ALM transitions to unregulated diode mode.
2. Current limitation at commutation. When an IGBT pair turns on while the complementary diode is conducting, the di/dt is limited only by parasitic line inductance. With typical industrial source impedance of 1–3 %, the di/dt exceeds the IGBT's safe operating area, producing phase-leg shoot-through and immediate F30002 / F30005 overcurrent trips.

Furthermore, when an ALM is connected without a reactor, the filter capacitance of the BLF resonates with the line inductance. The damping resistor (or AIM active circuit) is the only element that suppresses this resonance; without it, the BLF itself becomes a fault source, not a protective element.

5. DC-Link Pre-Charging Behavior Without ON Command

A second, less obvious hazard exists even before the IGBTs are pulsed:

Field implementation must therefore interconnect the Operation (EP terminal / DO of the ALM Control Unit) signal to the drives' OFF2 / enable pulses chain so that the Motor Modules cannot draw torque while the ALM is still in pre-charge. The same rule applies to Smart Line Modules.

6. Valid SINAMICS S120 ALM Component Topologies

The permissible connection orders, viewed from the grid toward the DC link, are:

The schematic below shows Topology B with explicit terminal identification:

7. Configuration Parameters p0220, p0221, and p0222

The ALM firmware uses a small set of parameters to identify the connected line-side module. The most critical is the line filter configuration parameter, which differs between firmware versions:

8. Step-by-Step Commissioning Procedure

The following procedure assumes an ALM 6SL3130-7TE21-6AA4 with BLF 6SL3000-0BE21-6DA0 and AIM 6SL3100-0BE21-6AB0. Adapt catalog numbers for other power classes.

8.1 Prerequisites

• STARTER V5.4 (or Startdrive V15 / V16 in TIA Portal)
• CF card with current SINAMICS firmware (≥ V5.2 SP3 recommended)
• DOK-specific line filter description file (LFD) installed in the project
• Wiring verified: BLF → AIM → ALM, with PE bonded to cabinet ground bar at each module
• DRIVE-CLiQ connections: AIM port X200 to ALM Control Unit X100, ALM to SMM (e.g., 6SL3120-1TE23-0AC0) to Motor Module

8.2 Procedure

1. Insert line filter description. In STARTER, right-click the ALM in the project tree and select Properties → Line Filter. Browse the catalog for the matching BLF + AIM pair and accept.
2. Confirm topology. The wizard displays Topology B. Confirm that the order shown matches the physical wiring: BLF → AIM → ALM.
3. Verify p0220[0]. Open the parameter list of the ALM and confirm p0220[0] = 2 (Active Interface Module). Do not leave this at 0 (unknown).
4. Verify p0221, p0222, p0223. The wizard should populate these from the LFD. If they read 0, the LFD is missing — re-install from the SINAMICS V5.2 SP3 DVD or Siemens Industry Online Support.
5. Configure pre-charging interlock. Wire the ALM's Operation (EP) signal to the OFF2 input of every downstream Motor Module. This prevents the SMM from drawing torque before the ALM has finished pre-charging.
6. Download project. Save to RAM, then to ROM on the CF card.
7. First power-up. Apply 24 V to the CU320-2; confirm DRIVE-CLiQ LED chain is solid green. Apply line voltage to the BLF input; observe DC-link voltage rising on the ALM operator panel. The pre-charge should complete in approximately 1.5 s for 16 kW class.
8. Enable pulses. Send the ON command. Confirm the DC link stabilizes at approximately 1.5 × V_LL_rms (e.g., 600 V DC on a 400 V line). If the DC link collapses to the rectified peak (≈ 565 V DC) or F30002 trips, the AIM is not recognized — return to step 1.
9. Enable motor. Issue the drive enable and run a no-load speed step (e.g., 100 rpm) on the SMM. Verify line current THDi < 5 % with a power analyzer.

9. Diagnostic Fault Codes and Troubleshooting Matrix

When a Booksize ALM is operated without the required reactor, the following SINAMICS fault codes are typical. Use the matrix to triage:

10. Field Verification and Commissioning Checks

After commissioning, perform the following verification. A correctly commissioned system will pass all four checks.

1. DC-link voltage steady-state: V_DC ≈ 1.5 × V_LL_rms within ±2 % at no load.
2. Line current waveform: Power analyzer (Fluke 435, Hioki PW3198, or equivalent) on the grid side of the BLF. THDi < 5 % at 100 % load.
3. DRIVE-CLiQ topology diagnostic: In STARTER/Startdrive, open Topology → Line Filter and confirm the BLF and AIM are both detected with green status. If only the BLF appears, the AIM DRIVE-CLiQ cable (X200) is missing or the AIM is unpowered.
4. Thermal check at full load: BLF and AIM heatsink temperatures must stabilize below their rated maxima (typically 80 °C for BLF, 70 °C for AIM at 40 °C ambient).

Formulas for the expected harmonic performance at the ALM terminals, assuming the AIM is correctly installed:

I_line,fundamental = P_out / (sqrt(3) × V_LL × cos φ × η)
I_THDi ≈ I_1 / (sqrt(1 + (I_h/I_1)²)) where I_h/I_1 is the harmonic current ratio

For the 16 kW ALM at 400 V, full load, unity power factor, η ≈ 0.97:

I_line ≈ 16000 / (1.732 × 400 × 1.0 × 0.97) ≈ 23.8 A (fundamental)
With AIM: THDi ≈ 4.4 % → I_rms,total ≈ 23.8 × sqrt(1 + 0.044²) ≈ 23.82 A
Without AIM (BLF only): THDi typically 30–40 % → I_rms,total ≈ 24.9 A and F30002 risk

11. Sizing Notes for Other Power Classes

The selection principle is identical at every ALM power class: pair the ALM with the matching BLF and either an AIM or HFD reactor + damping resistor at the same power rating. The 6SL3100-0BE21-6AB0 AIM is rated for the 16 kW class. For higher-power Booksize ALMs (e.g., 36 kW, 55 kW), use the corresponding AIM catalog suffix.

For further detail, consult the SINAMICS S120 Manual Collection on the Siemens Industry Online Support portal, specifically the SINAMICS S120 Function Manual Drive Functions and the SINAMICS S120 Equipment Manual for Booksize Power Units.