K2921-1 - Lincoln Electric Power Wave STT Module for S-Series and R-Series Welders

Upgrade Your Power Wave for STT Performance

Take your pipe welding and thin-gauge fabrication to the next level with the Lincoln Electric K2921-1 Power Wave STT Module. If you own a Power Wave S350 or S500 and need the legendary performance of STT (Surface Tension Transfer) for open root passes, this is the accessory you need. Instead of buying a completely separate STT II machine, this compact module attaches to your existing Power Wave setup, instantly upgrading it with advanced waveform capabilities. It is the perfect solution for shops that need flexibility—run standard MIG/Stick/TIG for most jobs, and switch to STT for critical root passes without changing power sources.

The K2921-1 isn't just about STT; it also gives you access to Rapid X for high-speed, low-distortion welding on stainless, and Low Fume Pulse for cleaner shop air. The kit comes ready to install with a Tweco-style power source output pigtail adapter cable and a 25-foot remote voltage sense lead, which is crucial for maintaining a stable arc in STT applications. The module communicates digitally with your welder via ArcLink, ensuring that the arc characteristics are adjusted thousands of times per second for the smoothest possible operation.

Installation is simple. The module can be mounted directly to the side or top of compatible Power Wave units using the included hardware, creating a tidy, all-in-one footprint. It is built tough for industrial environments and integrates perfectly into robotic cells using the Power Wave R-series. Whether you are welding process pipe, automotive exhaust systems, or thin sheet metal, the K2921-1 delivers the arc control necessary to reduce rework, eliminate spatter, and increase travel speeds.