The Siemens 6SL3121-2TE21-0AA4 is a Double Motor Module from the SINAMICS S120 booksize family, designated as a spare part for drives with external air cooling. It accepts a 600 V DC input and delivers 400 V 3 AC output at 9 A per channel (9 A/9 A), supporting optimized pulse patterns and extended Safety Integrated functions including DRIVE-CLiQ cabling.
This module carries a lifecycle stage of mature, meaning it is no longer in active new-product introduction but remains available through the supply chain. The documentation is dated 21.01.2021 with Änderungen vorbehalten © Copyright Siemens 2021, indicating the design and support status are stable.
The 9 A/9 A rating is per-motor-channel output at 400 V 3 AC, sized for two independent induction or synchronous servo motors up to roughly 5 kW each depending on duty cycle. The 600 V DC input rail is standard for SINAMICS S120 shared DC-link configurations, so this module integrates directly into an existing S120 booksize line-up with a common DC bus. The external air cooling requirement means the module must be mounted in a cabinet with forced airflow; it cannot rely on natural convection alone.
Deployment Context
As a booksize module, it snaps onto the S120 mounting rail in a control cabinet alongside a Smart Line Module or Active Line Module that provides the 600 V DC bus. The extended Safety Integrated functions (e.g., STO, SBC) are routed via DRIVE-CLiQ, so the drive controller must support the safety option. For a line-down spare, verify that the firmware version on the replacement matches the existing drive unit to avoid parameter incompatibility.