A motion system is a handful of architecture decisions before it is a parts list: which voltage level, which network, where the regenerated energy goes, how the machine stops safely. These are the decisions that are most expensive to change later.
Basics 01
Low-voltage DC is preferred on mobile robots, AGVs and systems that run on batteries or work close to people; the 48 V DC SML motors and the 70 V DC SDE drives are in this class. 220 V AC is the common level for single- or three-phase machines up to a few kilowatts (SD-LP). For higher power and large multi-axis machines, 380 V AC three-phase (SDU3) lowers the current and the cable cross-section.
Product selection guideBasics 02
The decision follows how tightly the axes are linked. EtherCAT for synchronised and interpolated motion, CANopen for a moderate number of independent axes, Modbus RTU for simple commands and monitoring, and pulse/direction or analog to use an existing controller's pulse or analog outputs. A fieldbus also brings the drive's alarm and status information back.
System architectureBasics 03
You need a braking resistor when the energy the load gives back while braking is more than the drive's DC-bus capacitors can absorb. High-inertia loads, short deceleration times, frequent stop-start and vertical loads moving down all raise that energy. Work it out from the motion profile, or watch during commissioning for overvoltage alarms during deceleration.
Braking resistorsBasics 04
STO (Safe Torque Off) is the drive safely removing the energy that would let the motor produce torque; the motor coasts, but the drive stays powered, so the machine restarts much faster. Used with a safety circuit of the right safety level, it can replace the contactor on the motor side. The machine's risk assessment decides which level is required.
Commissioning 05
Mount drives vertically so air enters at the bottom and leaves at the top, and leave the side and top clearances from the manual. Keep the cabinet temperature within the drive's operating range, and place heat sources such as braking resistors not above the drives but outside the cabinet or at the top where possible. The SD-LP drives, for example, are IP20 and must be used inside a closed cabinet.
Installation manualsDrive code, motor, controller and the alarm code you see: with those we reach the right answer faster.
