VFD vs Servo Drive: Key Differences
A side-by-side comparison of VFD and servo drive motor type, feedback, dynamic response, overload rating, cost, and applications for industrial engineers.
- Part number
- 1FK7081-2AC71-1QB0
SIMOTICS SSiemens 1FK7081-2AC71-1QB0 SIMOTICS S 1FK7-CT Synchronous Servo Motor 12Nm 2000rpm
SIMOTICS S 1FK7-CT synchronous servo motor, 12 Nm, 2000 rpm, 4.4 A, IP64, brake.
Description
About the 1FK7081-2AC71-1QB0
About the 1FK7081-2AC71-1QB0
The Siemens 1FK7081-2AC71-1QB0 is a SIMOTICS S 1FK7-CT synchronous servo motor rated 12 Nm continuous torque (M0 at 100K) at 2,000 rpm, with 4.4 A rated current and a shaft height of 80 mm. It uses natural cooling, carries IP64 protection, and includes a Drive-CLiQ single-turn absolute encoder (20-bit), with a holding brake.
Selection Notes
Same 12 Nm winding as the brake-less version of this shaft-height-80 frame, the highest continuous torque in this family comparison, but with an integrated holding brake for vertical or overhauling loads. The brake adds roughly 3 kg of mass and lowers shaft torsional stiffness to 76,000 Nm/rad against the brake-less version's 109,000 Nm/rad, so use it only where power-off holding is actually required.
Applications
Fits vertical-axis or gravity-loaded synchronous servo applications needing 12 Nm at 2,000 rpm, where the holding brake removes the need for a separate mechanical lock. The Drive-CLiQ encoder interface connects directly to Drive-CLiQ-enabled Siemens drive systems without separate encoder cabling.
Specification
Full specification
Engineering data 10
| Rated speed (100 K) | 2,000 rpm |
|---|---|
| Number of poles | 8 |
| Rated torque (100 K) | 10.0 Nm |
| Rated current | 4.4 A |
| Static torque (60 K) | 10.00 Nm |
| Static torque (100 K) | 12.00 Nm |
| Stall current (60 K) | 4.05 A |
| Stall current (100 K) | 5.00 A |
| Moment of inertia | 23.500 kgcm² |
| Efficiency | 93.0 % |
Physical constants 9
| Torque constant | 2.40 Nm/A |
|---|---|
| Voltage constant at 20º C | 154.5 V/1000*min¯¹ |
| Winding resistance at 20º C | 1.27 Ω |
| Rotating field inductance | 23.5 mH |
| Electrical time constant | 18.40 ms |
| Mechanical time constant | 1.33 ms |
| Thermal time constant | 45 min |
| Shaft torsional stiffness | 76,000 Nm/rad |
| Net weight of the motor | 15.9 kg Permanent-magnet synchronous |
Mechanical data 16
| Motor type | motor Compact |
|---|---|
| Shaft height | 80 |
| Cooling | Natural cooling |
| Radial runout tolerance | 0.050 mm |
| Concentricity tolerance | 0.10 mm |
| Axial runout tolerance | 0.10 mm |
| Vibration severity grade | Grade A |
| Connector size | M23 |
| Degree of protection | IP64 |
| Design acc. to Code I | IM B5 (IM V1, IM V3) |
| Temperature monitoring | Pt1000 temperature sensor |
| Electrical connectors | Connectors for signals and power rotatable |
| Color of the housing | Standard (Anthracite RAL 7016) |
| Holding brake | with holding brake |
| Shaft end | Feather key |
| Encoder system | Encoder AS20DQI: absolute encoder single-turn 20 bits |
Show all 61 specifications ↓ Show less ↑26 more values in Identification, Optimum operating point, Limiting data, Holding brake, Recommended Motor Module, Logistics.
Identification 5
| Part number | 1FK7081-2AC71-1QB0 |
|---|---|
| Brand | Siemens |
| Condition | New, factory sealed |
| Source | Siemens and its authorised distributors |
| Warranty | Manufacturer warranty |
Optimum operating point 2
| Optimum speed | 2,000 rpm |
|---|---|
| Optimum power | 2.1 kW |
Limiting data 4
| Max. permissible speed (mech.) | 6,000 rpm |
|---|---|
| Max. permissible speed (inverter) | 3,750 rpm |
| Maximum torque | 37.0 Nm |
| Maximum current | 17.2 A |
Holding brake 7
| Holding brake version | Permanent-magnet brake |
|---|---|
| Holding torque | 22.0 Nm |
| Power supply voltage | DC 24 V ± 10 % |
| Coil current | 0.9 A |
| Opening time | 200 ms |
| Closing time | 60 ms |
| Highest braking work | 1,400 J |
Recommended Motor Module 4
| Rated inverter current | 5A |
|---|---|
| Maximum inverter current | 15 A |
| Maximum torque | 33.30 Nm |
| Page 1 of 1 | Generated Sun Nov 1 02:21:09 CET 2026 |
Logistics 4
| Shipping weight | 14.2 kg |
|---|---|
| Ships from | Türkiye |
| Dispatch | — |
| Stock | On request |
Source: manufacturer data · Last verified: 01 Nov 2026
Documents
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Quick answers
Questions about the 1FK7081-2AC71-1QB0
What is the rated current of 1FK7081-2AC71-1QB0?
The rated current of 1FK7081-2AC71-1QB0 is 4.4 A.
What motor power is 1FK7081-2AC71-1QB0 rated for?
The rated motor power of 1FK7081-2AC71-1QB0 is 2.1 kW.
What is the HS code of 1FK7081-2AC71-1QB0 for customs?
The tariff (HS) code on file for 1FK7081-2AC71-1QB0 is 85015220.
Where does 1FK7081-2AC71-1QB0 ship from, and how fast?
1FK7081-2AC71-1QB0 ships from Türkiye. Shipping calculated at checkout · import duties and taxes paid on arrival.
Guides
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Series
Siemens SIMOTICS S
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- Siemens
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