AC servo motor
Siemens SIMOTICS S-1FK2
Naturally cooled compact servo motor family offered in several inertia classes (CT, HD, HI), built primarily for the SINAMICS S210 one-cable system and also usable on SINAMICS S120/S220.
Key specifications
| Ingress protection | IP64 to IP67 (range quoted for the 1FK2/1FT2/1FS2 group) |
|---|---|
| Rated torque | 0.16–40 Nm |
| Rated speed | up to 6000 |
| Power | 50–7,100 W |
| Frame sizes | 20, 100 mm |
| Supply | 1 AC 200-240 V (0.05-0.75 kW, 0.16-3.6 Nm); 3 AC 200-240 V (0.05-3.9 kW, 0.16-40 Nm); 3 AC 380-480 V (0.4-6.4 kW, 1.27-40 Nm) - combined 1FK2/1FT2 figures on S210 page |
| Feedback | single-turn absolute, multi-turn absolute, DRIVE-CLiQ digital interface with electronic nameplate |
| Overload | not published as a figure for 1FK2 alone |
Summarised in our own words from Siemens AG's published data; series maxima, individual models vary. Last checked 2026-10-29. Source 1 · Source 2 · Source 3 · Source 4
Notes on this data
Siemens publishes 1FK2 and 1FT2 figures partly combined. S210 page (current) gives 0.16-40 Nm and 0.05-6.4 kW for 1FK2/1FT2 together; 1FK2/1FT2 product page gives 1FK2 rated power 0.26-7.1 kW and a single rated torque figure of 34.5 Nm; 2022 brochure gives 1FK2 standstill torque CT 0.64-40 Nm, HD 0.16-16 Nm. torque_Nm_rated_max of 40 is the combined S210-page figure. Servo planetary gearmotor versions also offered. No peak torque figure published on the pages checked.
Specify Motion is not affiliated with Siemens AG. Siemens and SIMOTICS S-1FK2 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 a Siemens 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 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 | SIMOTICS S-1FK2 | SMK Series AC Servo Motors (SMK40S/60S… |
|---|---|---|
| Rated torque | 40 Nm | 47.8 Nm meets or exceeds |
| Peak torque | — | 119.5 Nm |
| Speed | — | 6,000 rpm |
| Power | 7,100 W | 7,500 W meets or exceeds |
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 | SIMOTICS S-1FK2 | SMH Series AC Servo Motors (SMH40S-SMH… |
|---|---|---|
| Rated torque | 40 Nm | 48 Nm meets or exceeds |
| Power | 7,100 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 | SIMOTICS S-1FK2 | ELM1 / ELM2 AC Servo Motors |
|---|---|---|
| Rated torque | 40 Nm | — |
| Power | 7,100 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.
Other ac servo motor series
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