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.
Siemens 1FK7040-2AK71-1QA0 SIMOTICS S 1FK7-CT servo motor delivers 1.6 Nm standstill torque and 0.69 kW rated power at 6000 rpm on a 600 V DC link. It is an 8-pole design with 1.9 A rated current, IP64 protection, a 20-bit single-turn absolute encoder (AS20DQI) with a DRIVE-CLiQ interface, and no holding brake.
This is the non-brake version of the 1FK7040-CT frame: it steps up from the 1FK7034 frame to shaft height 48 mm and an 8-pole design, giving a shaft torsional stiffness of 18,700 Nm/rad - well above the smaller 36 mm-frame motors in this range - while holding the same 1.6 Nm standstill torque at a higher 0.69 kW rated power. Without the brake, rotor inertia is 1.600 kgcm², lower than the brake version in the same frame; pick it where an external holding mechanism exists or the axis is horizontal.
1.6 Nm at 6000 rpm without a brake, with the higher torsional stiffness of the 48 mm frame, suits high-speed horizontal axes with demanding dynamic stiffness requirements, such as rotary indexing tables and fast pick-and-place mechanisms.
| Rated speed (100 K) | 6,000 rpm |
|---|---|
| Number of poles | 8 |
| Rated torque (100 K) | 1.1 Nm |
| Rated current | 1.9 A |
| Static torque (60 K) | 1.30 Nm |
| Static torque (100 K) | 1.60 Nm |
| Stall current (60 K) | 1.90 A |
| Stall current (100 K) | 2.35 A |
| Moment of inertia | 1.600 kgcm² |
| Efficiency | 88.0 % |
| Torque constant | 0.68 Nm/A |
|---|---|
| Voltage constant at 20º C | 43.4 V/1000*min¯¹ |
| Winding resistance at 20º C | 2.87 Ω |
| Rotating field inductance | 16.5 mH |
| Electrical time constant | 5.70 ms |
| Mechanical time constant | 3.00 ms |
| Thermal time constant | 25 min |
| Shaft torsional stiffness | 18,700 Nm/rad |
| Net weight of the motor | 3.2 kg Permanent-magnet synchronous |
| Motor type | motor Compact |
|---|---|
| Shaft height | 48 |
| Cooling | Natural cooling |
| Radial runout tolerance | 0.040 mm |
| Concentricity tolerance | 0.08 mm |
| Axial runout tolerance | 0.08 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 | without holding brake |
| Shaft end | Feather key |
| Encoder system | Encoder AS20DQI: absolute encoder single-turn 20 bits |
| Part number | 1FK7040-2AK71-1QA0 |
|---|---|
| Brand | Siemens |
| Condition | New, factory sealed |
| Source | Siemens and its authorised distributors |
| Warranty | Manufacturer warranty |
| Optimum speed | 6,000 rpm |
|---|---|
| Optimum power | 0.7 kW |
| Max. permissible speed (mech.) | 9,000 rpm |
|---|---|
| Max. permissible speed (inverter) | 9,000 rpm |
| Maximum torque | 5.1 Nm |
| Maximum current | 7.7 A |
| Rated inverter current | 3A |
|---|---|
| Maximum inverter current | 9A |
| Maximum torque | 5.10 Nm |
| Page 1 of 1 | Generated Sun Nov 1 02:14:52 CET 2026 |
| Shipping weight | 3.701 kg |
|---|---|
| Ships from | Türkiye |
| Dispatch | — |
| Stock | On request |
Source: manufacturer data · Last verified: 01 Nov 2026
No documents are on file for this part yet.
Ask us for the datasheetThe rated current of 1FK7040-2AK71-1QA0 is 1.9 A.
The rated motor power of 1FK7040-2AK71-1QA0 is 0.69 kW.
The tariff (HS) code on file for 1FK7040-2AK71-1QA0 is 85015100.
1FK7040-2AK71-1QA0 ships from Türkiye. Shipping calculated at checkout · import duties and taxes paid on arrival.
A side-by-side comparison of VFD and servo drive motor type, feedback, dynamic response, overload rating, cost, and applications for industrial engineers.
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