AC servo motor
ABB (Motion) eSM servo motors
Economy permanent-magnet AC servo motors in 40 to 180 mm flange sizes, 100 W to 7.5 kW and 0.32 to 48 Nm continuous torque, IP67 apart from shaft opening and connectors, with single- or multi-turn absolute encoders.
Key specifications
| Voltage (max) | 480 V |
|---|---|
| Ingress protection | IP67 (except shaft opening and connectors) |
| Rated torque | 0.32–48 Nm |
| Peak torque (max) | 119 Nm |
| Power | 100–7,500 W |
| Frame sizes | 40, 60, 80, 130, 180 |
| Feedback | single-turn or multi-turn absolute encoder (23-bit on 10-pole models) |
| Brake | optional 24 V holding brake on ESM06, ESM08, ESM13, ESM18 |
Summarised in our own words from ABB Asea Brown Boveri Ltd's published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1 · Source 2 · Source 3
Notes on this data
Product page technical data also says 'up to 15 kW' and 'up to 220 mm'; body text figures (100 W–7.5 kW, 40–180 mm) used. Peak torque 119 Nm from the e180/e190 catalogue (400 V eSM).
Specify Motion is not affiliated with ABB Asea Brown Boveri Ltd. ABB (Motion) and eSM servo motors are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Typical applications
Alternatives that meet or exceed these figures
Engineers often come to us with an ABB (Motion) part number and leave with an alternative that is easier to source, quicker to deliver or a better fit for the machine. These 3 series from our supply network are the closest match on published figures.
Kinco's established AC servo motor range from 40 to 180 mm frames, covering 50 W to 7.5 kW and up to 48 Nm rated torque. Standard feedback is a 2500-line incremental encoder with Hall commutation, with absolute options and a resolver on the 180 mm frame. Pairs with FD2S and CD2S drives.
| Published maximum | eSM servo motors | SMH Series AC Servo Motors (SMH40S-SMH… |
|---|---|---|
| Rated torque | 48 Nm | 48 Nm meets or exceeds |
| Peak torque | 119 Nm | — |
| Power | 7,500 W | 7,500 W meets or exceeds |
Kinco's current-generation AC servo motor line, matched to the JD2 and FD5P PRO drives. Small-inertia 40-80 mm frames run at 3000 rpm on 220 V; large-inertia 130 and 180 mm frames are 1500 rpm machines reaching 47.8 Nm rated and 7.5 kW, with 23-bit multi-turn absolute encoders as standard.
| Published maximum | eSM servo motors | SMK Series AC Servo Motors (SMK40S/60S… |
|---|---|---|
| Rated torque | 48 Nm | 47.8 Nm |
| Peak torque | 119 Nm | 119.5 Nm meets or exceeds |
| Speed | — | 6,000 rpm |
| Power | 7,500 W | 7,500 W meets or exceeds |
Leadshine's AC servo motors for the EL8/EL7/EL6 drives: ELM1 is the economy line and ELM2 the general-purpose line, both with 23-bit absolute encoders, IP65/IP67 sealing and up to 3.5x overload. The catalogue extends ELM2M to 22 kW and previews a 26-bit ELM3.
| Published maximum | eSM servo motors | ELM1 / ELM2 AC Servo Motors |
|---|---|---|
| Rated torque | 48 Nm | — |
| Peak torque | 119 Nm | — |
| Power | 7,500 W | 7,500 W meets or exceeds |
Figures are the highest published for each series and are not always measured the same way. A higher figure is not automatically a better choice: mounting, duty cycle, feedback, connectors and approvals matter too. An engineer will check the fit against your application before recommending anything.
What an AC servo motor is
An AC servo motor is a permanent-magnet synchronous motor designed for closed-loop control of position, speed and torque. A wound stator is driven by a servo drive with sinusoidal three-phase current, while magnets on the rotor follow the rotating field. A high-resolution encoder or resolver on the shaft feeds position back to the drive, which adjusts current many thousands of times a second. The result is precise, dynamic motion with high peak torque, typically about three times the continuous rating for short periods.
When engineers choose an AC servo motor
Choose an AC servo for machine axes needing fast, accurate motion under varying loads, such as packaging, robotics, machine tools and printing. Compared with steppers, servos keep torque at high speed and cannot silently lose position. The trade-offs are cost and set-up: a servo needs a matched drive, feedback and tuning. For simple, low-speed indexing with a steady load, a stepper may be cheaper. For very low speeds and high torque, a gearbox or direct-drive motor may be needed.
How to specify the ABB (Motion) eSM servo motors
Send these with your enquiry and an engineer can confirm the right eSM servo motors variant or an equivalent:
- Continuous and peak torque (Nm)
- Rated and maximum speed (rpm)
- Load inertia and inertia ratio
- Supply voltage: 230 V single-phase or 400 V three-phase
- Feedback: incremental or absolute encoder, resolution (bits)
- Holding brake, IP code and shaft options
- Flange size and mounting (mm)
Common mistakes to avoid
- Sizing on peak torque without checking RMS torque over the cycle
- Ignoring load-to-motor inertia ratio, which makes tuning hard
- Forgetting the brake is for holding, not dynamic stopping
- Using a motor and drive pair that the supplier has not matched
ABB (Motion) eSM servo motors: frequently asked questions
What is the ABB (Motion) eSM servo motors?
Economy permanent-magnet AC servo motors in 40 to 180 mm flange sizes, 100 W to 7.5 kW and 0.32 to 48 Nm continuous torque, IP67 apart from shaft opening and connectors, with single- or multi-turn absolute encoders. Published series figures include voltage 480 V, rated torque 0.32 Nm, rated torque 48 Nm, peak torque 119 Nm. It is made by ABB Asea Brown Boveri Ltd; Specify Motion can help source it or propose an equivalent.
Who makes the ABB (Motion) eSM servo motors?
The ABB (Motion) eSM servo motors is made by ABB (Motion) (ABB Asea Brown Boveri Ltd) and is listed here for engineers comparing options. Specify Motion is not affiliated with ABB Asea Brown Boveri Ltd; brand names are used only to identify the product.
What is the voltage of the ABB (Motion) eSM servo motors?
The published series maximum voltage is 480 V. Individual models and sizes in the eSM servo motors range vary, so check the exact variant against your duty cycle, mounting and environment, or ask our engineers to confirm the right size for you.
Is there an alternative to the ABB (Motion) eSM servo motors?
Yes. On published figures, Kinco SMH Series AC Servo Motors (SMH40S-SMH180D) and Kinco SMK Series AC Servo Motors (SMK40S/60S/80S, SMK130G, SMK180G) are the closest match from our supply network. An engineer confirms the fit against your application before recommending anything.
What is the inertia ratio in servo sizing?
The inertia ratio compares the load inertia reflected to the motor shaft with the motor's rotor inertia. High ratios make the axis harder to tune and slower to settle. Many engineers aim for below about 10:1, and lower for highly dynamic axes, using a gearbox to reduce reflected inertia where needed.
Do AC servo motors need an absolute encoder?
Not always. Incremental encoders need a homing routine after power-up, which is acceptable on many machines. Absolute encoders know their position at power-on, avoiding homing, which saves time and suits robots and multi-axis machines. Multi-turn absolute encoders track turns even when power is off.
Further reading: How to select a servo motor · Servo vs stepper · Servo and stepper motors
Other ac servo motor series
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