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
- 1FK7042-2AK71-1QB0
SIMOTICS SSiemens 1FK7042-2AK71-1QB0 SIMOTICS S-1FK7 1FK7-CT 0.94kW 3Nm 6000rpm Servo Motor
SIMOTICS S-1FK7 1FK7-CT synchronous servo motor, 0.94kW, 3Nm M0, 6000rpm, 600V DC link, with holding brake, IP64, DRIVE-CLiQ encoder.
Description
About the 1FK7042-2AK71-1QB0
About the 1FK7042-2AK71-1QB0
The Siemens 1FK7042-2AK71-1QB0 is a SIMOTICS S-1FK7 (1FK7-CT) permanent-magnet synchronous servo motor rated 0.94 kW at 6,000 rpm, delivering 3 Nm standstill torque (M0, 100K) from a 600 V DC link. It integrates a holding brake, carries a single-turn 20-bit DRIVE-CLiQ absolute encoder (AS20DQI), and is naturally cooled in a shaft height 48, IMB 5 (IM V1/V3) housing rated IP64.
Selection Notes
Same 6,000 rpm winding as the brake-free variant of this frame, with an integrated holding brake — weight rises from 4.6 to 5.3 kg and shaft torsional stiffness drops from 15,500 to 11,400 Nm/rad. Fit it on high-speed axes that must still hold position at standstill, such as an overhung spindle or gravity-loaded rotary axis; on purely horizontal high-speed axes, the brake-free winding is lighter. The 2.5 A rated current and 0.68 Nm/A torque constant are unchanged by the brake.
Applications
Used as the servo motor in high-speed machine axes that must hold position without drive power — indexed rotary tables, overhung spindle axes, and winding stations — driven through a DRIVE-CLiQ-based servo drive via the AS20DQI single-turn absolute encoder interface. The integrated holding brake keeps the axis in position during an E-stop or power loss.
Specification
Full specification
Engineering data 10
| Rated speed (100 K) | 6,000 rpm |
|---|---|
| Number of poles | 8 |
| Rated torque (100 K) | 1.5 Nm |
| Rated current | 2.5 A |
| Static torque (60 K) | 2.50 Nm |
| Static torque (100 K) | 3.00 Nm |
| Stall current (60 K) | 3.55 A |
| Stall current (100 K) | 4.40 A |
| Moment of inertia | 3.200 kgcm² |
| Efficiency | 89.0 % |
Physical constants 9
| Torque constant | 0.68 Nm/A |
|---|---|
| Voltage constant at 20º C | 44.5 V/1000*min¯¹ |
| Winding resistance at 20º C | 1.15 Ω |
| Rotating field inductance | 8.6 mH |
| Electrical time constant | 7.50 ms |
| Mechanical time constant | 2.15 ms |
| Thermal time constant | 30 min |
| Shaft torsional stiffness | 11,400 Nm/rad |
| Net weight of the motor | 5.3 kg Permanent-magnet synchronous |
Mechanical data 16
| 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 | 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 | 1FK7042-2AK71-1QB0 |
|---|---|
| Brand | Siemens |
| Condition | New, factory sealed |
| Source | Siemens and its authorised distributors |
| Warranty | Manufacturer warranty |
Optimum operating point 2
| Optimum speed | 5,000 rpm |
|---|---|
| Optimum power | 1.0 kW |
Limiting data 4
| Max. permissible speed (mech.) | 9,000 rpm |
|---|---|
| Max. permissible speed (inverter) | 9,000 rpm |
| Maximum torque | 10.5 Nm |
| Maximum current | 15.3 A |
Holding brake 7
| Holding brake version | Permanent-magnet brake |
|---|---|
| Holding torque | 4.0 Nm |
| Power supply voltage | DC 24 V ± 10 % |
| Coil current | 0.5 A |
| Opening time | 70 ms |
| Closing time | 30 ms |
| Highest braking work | 150 J |
Recommended Motor Module 4
| Rated inverter current | 5A |
|---|---|
| Maximum inverter current | 15 A |
| Maximum torque | 10.30 Nm |
| Page 1 of 1 | Generated Sun Nov 1 02:16:28 CET 2026 |
Logistics 4
| Shipping weight | 5.4 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 1FK7042-2AK71-1QB0
What is the rated current of 1FK7042-2AK71-1QB0?
The rated current of 1FK7042-2AK71-1QB0 is 2.5 A.
Which supply voltage is 1FK7042-2AK71-1QB0 rated for?
The rated operational voltage of 1FK7042-2AK71-1QB0 is 600 V DC.
What motor power is 1FK7042-2AK71-1QB0 rated for?
The rated motor power of 1FK7042-2AK71-1QB0 is 0.94 kW.
What is the HS code of 1FK7042-2AK71-1QB0 for customs?
The tariff (HS) code on file for 1FK7042-2AK71-1QB0 is 85015220.
Where does 1FK7042-2AK71-1QB0 ship from, and how fast?
1FK7042-2AK71-1QB0 ships from Türkiye. Shipping calculated at checkout · import duties and taxes paid on arrival.
Guides
Guides for servo drives
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Series
Siemens SIMOTICS S
- Brand
- Siemens
- Series
- SIMOTICS S
