Siemens 6SL3120-1TE21-8AA4 SINAMICS S120 Single Motor Module
Booksize Format | 18A | 9.7 kW | 600 VDC Input | 400V 3AC | Drive-CLiQ | Extended Safety Integrated | IP20
One Axis. Full Performance. No Compromise.
In any multi-axis automation system, not every axis needs to share its inverter with another. High-torque feed axes, demanding spindle drives, and critical positioning axes — particularly those with heavy dynamic loads or independent safety requirements — deserve dedicated drive resources. The Siemens 6SL3120-1TE21-8AA4 is a single-axis motor module in the SINAMICS S120 booksize format, delivering 18A rated output at 9.7 kW to a single motor with the full intelligence, safety architecture, and Drive-CLiQ connectivity that defines the S120 platform.
Where a double motor module divides resources between two axes, this module dedicates everything to one: the full 18A output current, the independent safe standstill input, the individual safe motor brake control, and the complete Extended Safety Integrated function set — all on a single, dedicated channel within the booksize stack.
Technical Specifications
| Parameter |
Value |
| Part Number |
6SL3120-1TE21-8AA4 |
| Series |
SINAMICS S120 |
| Module Type |
Single Motor Module (1-axis inverter) |
| Frame Format |
Booksize |
| DC Link Input Voltage |
510 - 720 VDC (nominal 600 VDC) |
| Output Voltage |
400 V, 3-phase AC |
| Rated Output Current |
18 A |
| Base Load Current |
15.3 A |
| Rated Output Power |
9.7 kW |
| Output Frequency Range |
0 to 650 Hz (servo mode) |
| Pulse Frequency |
4.0 kHz |
| 24V DC Electronics Supply |
-15% to +20% tolerance |
| Cooling Method |
Internal air cooling |
| Communication Interface |
Drive-CLiQ |
| Safety Functions |
Extended Safety Integrated |
| Safety Standard Compliance |
SIL 2 (IEC 61508) / PL d, Category 3 (EN ISO 13849-1) |
| Certifications |
CE, cULus |
| Safe Standstill Inputs |
1 |
| Safe Motor Brake Control |
1 |
| Temperature Sensor Input |
1 |
| Protection Rating |
IP20 |
| Operating Temperature |
0°C to +40°C |
| Weight |
Approx. 5 kg |
| Country of Origin |
Germany |
18A Rated / 15.3A Base Load: Understanding the Two Current Figures
Two current ratings appear on this module's specification, and the distinction matters when sizing an S120 drive group. The 18A rated current is the peak steady-state capability for demanding servo and vector applications — the number that matches against motor nameplate current for continuous high-torque duty. The 15.3A base load current is the de-rated figure for heavy-duty applications where the motor runs continuously at elevated torque without intermittent deceleration to allow thermal recovery.
For the majority of servo feed axis applications with their inherent acceleration-deceleration duty cycles, the full 18A rated current applies. For continuous-process applications — spindle drives maintaining constant cutting load, conveyor drives under sustained torque — the 15.3A base load current is the conservative sizing reference. Choosing between the two depends on the specific duty profile, and Siemens' SIZER engineering software can calculate the appropriate figure for a given application cycle.
Extended Safety Integrated: Certified to SIL 2 and PL d
The safety architecture of the 6SL3120-1TE21-8AA4 is not an add-on feature — it's resident firmware within the module itself, certified to Safety Integrity Level 2 per IEC 61508 and Performance Level d, Category 3 per EN ISO 13849-1. This means the safety functions meet independently verified standards for fault tolerance and failure probability, which matters when the module is incorporated into a machine's formal safety assessment.
The available Extended Safety Integrated functions include Safe Torque Off (STO), Safe Stop 1 (SS1), Safely Limited Speed (SLS), and Safe Brake Control (SBC). Each function operates through the dedicated safe standstill input and brake control output on the module, without requiring an external safety relay or safety PLC for the drive-resident functions. The motor's temperature sensor input provides additional thermal protection monitoring as part of the module's comprehensive protection scheme.
For machine builders working to EN Machinery Directive requirements, having safety functions certified at this level and resident in the drive module simplifies the safety validation documentation considerably — the module's certification covers the drive-side safety chain.
Drive-CLiQ: Intelligence Wired In
The Drive-CLiQ interface is how the 6SL3120-1TE21-8AA4 becomes more than a power stage. Through a single digital fiber or copper cable to the Control Unit, the module communicates real-time feedback, fault status, parameter data, and its own electronic type plate — the built-in hardware identification that lets the Control Unit recognize exactly what module is present and configure drive objects accordingly.
On power-up, the Control Unit reads the module's type plate automatically. In a replacement scenario, this means the system recognizes the new module without manual parameter entry. For the commissioning engineer, it eliminates a potential configuration error that could otherwise show up during first power-on. For the maintenance technician swapping a faulty module, it means the machine can be returned to service faster.
The module ships with a Drive-CLiQ cable pre-cut for inter-module connection within the booksize stack.
650 Hz Output Frequency: The Hidden Capability
The 650 Hz output frequency ceiling in servo control mode is substantially higher than most standard VFD inverters, and it exists for good reason. Synchronous servo motors with high pole counts require elevated electrical frequencies to produce practical mechanical speeds — a 6-pole motor at 4,500 RPM needs 225 Hz output; a 10-pole motor at 6,000 RPM needs 500 Hz. The module's 650 Hz ceiling accommodates these high-speed servo motor configurations without requiring a specialty inverter.
For standard 4-pole induction motors in vector control applications, the 300 Hz ceiling in vector control mode covers shaft speeds well above any practical requirement. The wide frequency range ensures one module platform serves both servo and vector control applications without substitution.
System Integration: Where This Module Fits
The 6SL3120-1TE21-8AA4 occupies a single slot in the S120 booksize drive stack, positioned downstream of the Line Module on the shared DC bus. It connects via Drive-CLiQ to any compatible S120 Control Unit — CU320-2 for multi-axis applications, CU310-2 for simpler configurations, or integrated controllers in SIMOTION D or SINUMERIK CNC platforms.
The module supports all three SINAMICS S120 control modes: servo control for position-controlled feed axes, vector control for high-performance induction motor drives, and V/f control for simple speed-controlled applications where full closed-loop tuning is not required. Mode selection is a software parameter change, not a hardware modification.
Compatible Control Unit and system platforms include:
- SINUMERIK 840D sl — CNC machine tool feed and spindle axes
- SIMOTION D — coordinated motion control for packaging, printing, and converting
- CU320-2 — general multi-axis automation
- CU310-2 — single-axis and simpler system architectures
AA4 Generation: Current Production Status
The AA4 suffix identifies this as the current active hardware generation in the 18A single motor module class, replacing the earlier AA3 variant (6SL3120-1TE21-8AA3). Drive-CLiQ's automatic type plate recognition handles backward compatibility transparently — an AA4 module inserted in place of an AA3 in an existing S120 system is recognized by the Control Unit without firmware changes or manual parameter entries.
Frequently Asked Questions
Q1: What is the practical difference between choosing this single motor module versus a double motor module for a two-axis application?
A double motor module (such as the 6SL3120-2TE21-8AA4, rated 2 × 18A) shares its current rating between two axes. If both axes rarely peak simultaneously and neither requires continuous full-current output, the double module delivers adequate performance in half the cabinet slot width. The single module dedicates the full 18A and all safety resources to one axis — the right choice when one axis requires continuous high torque, independent safety events, or guaranteed peak current that cannot be shared. For high-torque machining spindles or heavy gantry axes, single modules are typically the appropriate specification.
Q2: Can this module operate with 400V AC line supplies without a Line Module?
No. The 6SL3120-1TE21-8AA4 accepts DC link input only (510-720 VDC). It requires a SINAMICS S120 Line Module upstream to convert the incoming 3-phase AC supply to the DC bus voltage. The Line Module also handles regeneration — returning braking energy to the supply during deceleration. The motor module itself has no AC input capability.
Q3: What SINAMICS S120 Line Modules are compatible with this motor module?
Any S120 booksize Line Module that maintains 510-720 VDC on the DC bus is electrically compatible — including the Smart Line Module, Basic Line Module, and Active Line Module variants in the appropriate power ratings. The choice between these line module types affects whether the system supports power regeneration and what power quality compensation is needed, but any of them will power the 6SL3120-1TE21-8AA4 correctly within the DC bus voltage range.
Q4: Does the AA4 module replace the AA3 directly in existing installations?
Yes, in the vast majority of S120 booksize systems. The electrical specifications, physical dimensions, Drive-CLiQ interface, and safety function set are identical between AA3 and AA4. The Control Unit reads the AA4's electronic type plate on power-up and configures the drive object without manual intervention. Siemens' industry support forum confirms that the AA4 replaces the AA3 in SIMOTION-based systems — the drive's firmware and parameter data download from the controller handles the transition.
Q5: What typically causes failure in this module, and what should be inspected preventively?
The most common failure modes in S120 booksize motor modules are IGBT transistor failures from motor-side faults (winding shorts, phase-to-phase faults), capacitor degradation over operating years, and cooling fan wear. Preventive measures include periodic inspection of the internal fan for correct speed and clean airflow, monitoring the DC bus voltage for abnormal levels that stress the capacitors, and ensuring motor insulation integrity is checked during planned maintenance intervals rather than waiting for a module fault to indicate a motor problem. Module temperature readings via Drive-CLiQ can provide early warning of inadequate airflow before a thermal shutdown occurs.
Your message must be between 20-3,000 characters!
English
