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
- 1FK7042-2AF21-1QA0
SIMOTICS SSiemens 1FK7042-2AF21-1QA0 SIMOTICS S-1FK7 1FK7-CT 0.82kW 3Nm 3000rpm Servo Motor
SIMOTICS S-1FK7 1FK7-CT synchronous servo motor, 0.82kW, 3Nm M0, 3000rpm, 300V DC link, no holding brake, IP64, DRIVE-CLiQ encoder.
Description
About the 1FK7042-2AF21-1QA0
About the 1FK7042-2AF21-1QA0
The Siemens 1FK7042-2AF21-1QA0 is a SIMOTICS S-1FK7 (1FK7-CT) permanent-magnet synchronous servo motor rated 0.82 kW at 3,000 rpm, delivering 3 Nm standstill torque (M0, 100K) from a 300 V DC link. It has no 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
This winding runs on a 300 V DC link at 3,000 rpm rated speed — use it only with drives whose DC bus is limited to 300 V; the 600 V-rated windings in this frame (2,000 rpm, 3,000 rpm, or 6,000 rpm nominal) are the choice for standard 600 V DC-link drives. At 0.76 Nm/A torque constant and 1.44 Ω winding resistance, this winding draws more current for the same 3 Nm torque (3.5 A rated) than the 600 V windings in the same frame — check drive current headroom before specifying it. No holding brake is fitted; the with-brake version of this winding is the choice where the axis must hold position without drive power.
Applications
Used as the servo motor in single- or multi-axis machine motion on 300 V DC-link drive systems — common on some regional or OEM machine platforms — driven through a DRIVE-CLiQ-based servo drive via the AS20DQI single-turn absolute encoder interface. The naturally-cooled IMB 5 housing suits panel- or machine-frame-mounted installations without forced-air cooling.
Specification
Full specification
Engineering data 10
| Rated speed (100 K) | 3,000 rpm |
|---|---|
| Number of poles | 8 |
| Rated torque (100 K) | 2.6 Nm |
| Rated current | 3.5 A |
| Static torque (60 K) | 2.50 Nm |
| Static torque (100 K) | 3.00 Nm |
| Stall current (60 K) | 3.20 A |
| Stall current (100 K) | 3.95 A |
| Moment of inertia | 2.900 kgcm² |
| Efficiency | 88.0 % |
Physical constants 9
| Torque constant | 0.76 Nm/A |
|---|---|
| Voltage constant at 20º C | 49.6 V/1000*min¯¹ |
| Winding resistance at 20º C | 1.44 Ω |
| Rotating field inductance | 10.6 mH |
| Electrical time constant | 7.40 ms |
| Mechanical time constant | 2.15 ms |
| Thermal time constant | 30 min |
| Shaft torsional stiffness | 15,500 Nm/rad |
| Net weight of the motor | 4.6 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 | without holding brake |
| Shaft end | Feather key |
| Encoder system | Encoder AS20DQI: absolute encoder single-turn 20 bits |
Show all 54 specifications ↓ Show less ↑19 more values in Identification, Optimum operating point, Limiting data, Recommended Motor Module, Logistics.
Identification 5
| Part number | 1FK7042-2AF21-1QA0 |
|---|---|
| Brand | Siemens |
| Condition | New, factory sealed |
| Source | Siemens and its authorised distributors |
| Warranty | Manufacturer warranty |
Optimum operating point 2
| Optimum speed | 3,000 rpm |
|---|---|
| Optimum power | 0.8 kW |
Limiting data 4
| Max. permissible speed (mech.) | 9,000 rpm |
|---|---|
| Max. permissible speed (inverter) | 5,800 rpm |
| Maximum torque | 10.5 Nm |
| Maximum current | 13.8 A |
Recommended Motor Module 4
| Rated inverter current | 4A |
|---|---|
| Maximum inverter current | 8A |
| Maximum torque | 6.00 Nm |
| Page 1 of 1 | Generated Sun Nov 1 02:15:41 CET 2026 |
Logistics 4
| Shipping weight | 5.101 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 1FK7042-2AF21-1QA0
What is the rated current of 1FK7042-2AF21-1QA0?
The rated current of 1FK7042-2AF21-1QA0 is 3.5 A.
Which supply voltage is 1FK7042-2AF21-1QA0 rated for?
The rated operational voltage of 1FK7042-2AF21-1QA0 is 300 V DC.
What motor power is 1FK7042-2AF21-1QA0 rated for?
The rated motor power of 1FK7042-2AF21-1QA0 is 0.82 kW.
What is the HS code of 1FK7042-2AF21-1QA0 for customs?
The tariff (HS) code on file for 1FK7042-2AF21-1QA0 is 85015220.
Where does 1FK7042-2AF21-1QA0 ship from, and how fast?
1FK7042-2AF21-1QA0 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
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