The honest one-line version: G120 is a superb single-axis workhorse; S120 is a drive system. Paying for S where G suffices wastes money; forcing G where S belongs wastes engineering.
Architecture is the real difference
A G120 is self-contained: control unit plus power module, one motor, own rectifier. S120 is modular: infeed modules feed a shared DC bus, motor modules hang off it, and a control unit coordinates axes over DRIVE-CLiQ. That shared bus is the key feature — braking energy from one axis feeds accelerating axes directly, and one regenerative infeed (ALM) serves the whole lineup.
Choose G120 when
- Single axes: pumps, fans, conveyors, mixers — including demanding sensorless vector duty.
- Distributed machines where drives live near motors.
- Simplicity of service matters most: parameter card swap, done.
Choose S120 when
- Coordinated multi-axis motion: winders, slitting lines, presses, printing.
- Servo performance, high-end encoder support, safety motion functions beyond STO.
- Energy exchange between axes is significant — the DC bus is free regeneration.
- You need engineered options: ALM with clean input current, high overload duty cycles.
The gray zone is a machine with three or four independent-ish axes: count panel space, infeed hardware and engineering hours before assuming multiple G120s are cheaper. Above a handful of axes, S120 usually wins on the total.
FAQ
Can G and S mix on one machine? Routinely — S120 lineup for the coordinated core, G120 for the auxiliary fans and pumps around it.
Is S120 harder to service? Different, not harder: components swap cleanly, but the topology means service staff need a day of familiarization. We include it in handover.
Zone Otomasyon engineers both families daily — the quote tells you which and why. Drive system design.