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Servo Drives

Servo drives deliver closed-loop motor control for positioning, speed, and torque applications that require precision and repeatability beyond what standard variable frequency drives provide. PLC Direct supplies AC servo drives and servo amplifiers from leading automation manufacturers as surplus sealed, refurbished, and used hardware, supporting replacement and lifecycle maintenance of installed servo drive systems across discrete manufacturing, machine tool, and packaging environments.

Where Are Servo Drives Used in Industrial Environments?

Industrial servo drives are used wherever a machine axis requires precise closed-loop control of position, speed, or torque in coordination with a servo motor and encoder feedback. They are standard equipment in discrete manufacturing, machine tool, packaging, and assembly applications where motion accuracy directly affects output quality.

Facilities and operations that depend on servo drives include:

CNC machine tool installations running multi-axis spindle and feed drives where AC servo drives are matched to specific motor and encoder configurations.

Packaging and filling lines where servo drive control governs registration, cut-to-length, and synchronized multi-axis motion on high-speed equipment.

Automotive and metal fabrication plants using servo amplifiers for press, welding, and assembly robot axis control.

Printing and converting operations where web tension and registration depend on tightly synchronized closed-loop motion control across multiple driven axes.

Plastics and injection molding facilities running industrial servo drives for clamp, injection, and ejector axis control on installed molding machines.

When an AC servo drive fails on a production machine, sourcing a matched replacement by part number is the fastest way to restore the axis and resume normal output.

Which Brands of Servo Drives Does PLC Direct Stock?

PLC Direct stocks AC servo drives and servo amplifiers from major industrial automation manufacturers.

Siemens SINAMICS S120: The SINAMICS S120 is a modular multi-axis servo drive system covering Motor Modules, Control Units, and Line Modules for coordinated closed-loop motion control in CNC, packaging, and industrial machine applications.

Schneider Electric Lexium 32: The Lexium 32 is a single-axis AC servo drive family for machine applications from 0.15 kW to 7 kW, compatible with BMH and BSH servo motors, available across multiple current ratings.

Yaskawa Sigma Series SERVOPACKs: The Sigma-7 and earlier-generation SERVOPACKs are industrial servo drives for precision positioning and speed-control applications, available alongside compatible Sigma Series servo motors and cables.

Indramat DDS, TDM, and KDS Series: The Indramat DDS, TDM, and KDS series are legacy AC servo drives available across multiple power and current variants, supporting maintenance teams keeping installed Indramat servo drive systems in operation where replacement is not yet feasible.

All servo drives at PLC Direct are available as surplus sealed, refurbished, and used, depending on current inventory.

What Should You Know Before Ordering Servo Drives?

Hardware condition options: PLC Direct supplies servo drives as surplus sealed, refurbished, and used hardware. Surplus sealed units are factory-sealed stock in original packaging; refurbished units have been tested and restored to operational condition. Used hardware has been previously installed and carries the same 1-year PLC Direct warranty as all other condition grades.

Compatibility and part identification: AC servo drives are matched to specific motor families by encoder interface type, power rating, and firmware version; a replacement must match the installed drive's full part number to ensure compatibility with the motor, feedback device, and control system. For legacy servo amplifiers such as the Indramat DDS, TDM, and KDS series, the original nameplate part number is the most reliable reference, as these systems are no longer in active production and substitution between variants is not straightforward.

Warranty: All servo drive hardware purchased from PLC Direct carries a standard 1-year warranty covering defects and functionality, applicable to surplus sealed, refurbished, and used products.

PLC Direct supplies servo drive hardware for replacement and maintenance purposes and does not provide system design, programming, or integration services.

Frequently Asked Questions

A servo drive powers and regulates a servo motor in response to commands; a motion controller generates those commands, managing position profiles, velocity ramps, and multi-axis coordination. In most systems, the two are separate hardware items, though some manufacturers offer drive-integrated motion controllers that combine both functions in a single unit.

In most cases, no. Servo drives and motors are matched by encoder interface type, feedback protocol, and motor electrical parameters, and substituting across manufacturers typically requires engineering validation that goes beyond a drop-in replacement. The safest approach is to replace like-for-like using the original part number for both the drive and the motor.

Most servo drives are configured to disable the motor output on fault detection, which causes the controlled axis to stop or drift depending on whether a brake is fitted. The drive typically holds a fault code that identifies the cause, such as overcurrent, encoder loss, or thermal overload, which helps diagnose whether the drive itself has failed or whether the fault originates in the motor or wiring.

Service life depends heavily on operating environment, thermal load, and maintenance practices, but servo drives in well-maintained installations commonly remain in service for 10 to 20 years. Capacitor degradation and power component wear are the most common age-related failure modes.

Regenerative braking occurs when a servo drive recovers energy from a decelerating motor rather than dissipating it as heat. Drives with regenerative capability can return that energy to the DC bus or mains supply, which is particularly relevant in multi-axis systems and high-cycle applications where braking energy is significant.