AC Servo Motors

Choosing AC Servo Motors components

AC servo motor replacement is tightly bound to the matched drive family — the drive expects a specific feedback type, winding voltage, and motor coding. A motor with the right nameplate torque but the wrong feedback or encoder battery state will not commission on the existing drive without additional work.

Specs to confirm before ordering:

Exact OEM part number with all suffix codes
Rated continuous torque and rated speed
Peak torque and its duty cycle rating
Winding voltage class: 200 V, 400 V, 480 V — must match drive supply
Inertia class: low-inertia (high-acceleration) vs. medium/high-inertia (smoother on high-inertia loads)
Feedback: incremental encoder, sin/cos encoder, absolute serial (BiSS-C, EnDat 2.2, HIPERFACE, Yaskawa serial), battery vs. battery-less multi-turn
Feedback resolution (e.g., 17-bit single-turn, 24-bit absolute)
Shaft: straight, keyed, splined; with or without keyway
Brake option (holding brake voltage is typically 24 VDC)
Connector orientation: straight, angled, fixed cable
IP rating: IP65, IP67, or IP69K for washdown stainless

Common gotchas: within a single OEM family, low-inertia and medium-inertia variants of the same frame size are not drop-in interchangeable — the drive's tuning autotunes around the motor's inertia, and a different inertia class changes the achievable bandwidth. Absolute encoders with battery-backed multi-turn require the battery to be installed and charged on first power-up; depleted batteries on surplus motors lose the absolute position reference. Yaskawa SGMGV and SGMGH share frame size but differ in winding speed; substituting one for the other shifts the speed-torque curve. Holding brakes are typically rated for static holding only, not for repeated dynamic stops.

Typical applications: indexing axes on packaging and converting machines, X-Y-Z gantries, robotic arms, machine-tool feed axes, and high-precision pick-and-place. On legacy systems, in-kind OEM replacement preserves the drive's tuning, the encoder pairing, and the mechanical interface.

For obsolete AC servo motors, send the OEM part number for a sourcing quote.

Do you stock obsolete AC servo motors?

Yes. Discontinued Allen-Bradley MP-series first generations, Yaskawa Sigma-II/III SGM motors, Mitsubishi HF/HC series, and Siemens 1FK6 are sourced through our supplier network.

Will a Sigma-V motor work on a Sigma-7 drive?

Within Yaskawa's published compatibility tables, often yes — confirm the feedback type and rated current match the drive's supported list. Outside those tables, the pairing is not guaranteed.

What is the absolute encoder battery state on surplus motors?

Battery-backed absolute encoders on surplus motors may have depleted batteries — the absolute position reference is lost but the motor and encoder still function. We state battery condition where known and can supply replacement batteries on request.

Can I mix low-inertia and medium-inertia motors of the same size?

Mechanically possibly, electrically yes, but the drive's tuning will be different. Plan for retuning if you cross inertia classes within the same frame.

Does the motor include the brake holding circuit?

The holding brake itself is integrated when the motor part number specifies it. The 24 VDC supply and brake release relay are typically external — sometimes on the drive, sometimes on a separate brake-release module.

What is the warranty?

12 months functional warranty. Damage from incorrect drive parameters, miswired feedback, mechanical overload, or operation outside rated speed/temperature is not covered.

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