Siemens 1FL6042-2AF21-1AB1 Servo Motor

✅ Model Interpretation

1FL6042-2AF21-1AB1

1FL6: SIMOTICS S-1FL6 V90 servo motor series

042: Frame size SH40, 0.75kW

2: Low inertia (LI)

A: AC230V single-phase / three-phase

F21: Incremental TTL encoder, 2500ppr, cable outlet

1: B5 flange mounting

A: With parallel key; B: With electromagnetic brake

Reference: 1AA1 = Same specification without brake

📋 Core Technical Specifications

🛠️ Application Scenarios

Low inertia & high dynamic response, suitable for short-cycle positioning:

SMT machines, dispensing machines, small gantries

Packaging equipment, handling manipulators, conveyor positioning

Machine tool feed axes, inspection tooling

📌 Matching Components for Selection

1. Recommended drives: 6SL3210-5FB10-8UA0 (Pulse type) / 6SL3210-5FB10-8UF0 (PN PROFINET)
2. Power cable: e.g. 6FX3002-5CK01-1AD0
3. Encoder cable: e.g. 6FX3002-2DB10-1AD0

⚠️ Installation & Maintenance Notes

1. Ambient temperature: 0～40℃ without derating; max relative humidity ≤90%, no condensation
2. Brake: Power-off holding brake, released when powered on. The brake cannot be used for dynamic braking during operation, only for holding at standstill.
3. IP65: Motor body dust-tight and splash-proof; cable connectors must be tightly fastened. Not suitable for long-term immersion.
4. Mounting: IM B5 flange, horizontal or vertical installation. Reserve sufficient brake load margin for vertical mounting.
5. Key inspection points for used motors: Encoder waveform, brake pull-in/release performance, 3-phase winding balance, insulation resistance, bearing noise.

🔁 Alternative Models in the Same Series

1FL6042-2AF21-1AA1: Same parameters, without brake

1FL6042-2AF21-1MB1: Single-turn absolute encoder, with brake

1FL6042-2AF21-1MA1: Single-turn absolute encoder, without brake

Shaft Parameters of Siemens 1FL6042-2AF21-1AB1

Shaft Diameter: Φ10 mm, with parallel keyway, shaft tolerance N

Parallel key dimension: 3×3×16 mm

Shaft extension length: 22 mm

Flange: B5, frame height 40mm (SH40)

Troubleshooting Checklist for Siemens 1FL6042-2AF21-1AB1 (V90 0.75kW with Brake)

Safety Precaution: Power off and wait 5 minutes for DC bus discharge before plugging/unplugging cables. High voltage hazard. Apply mechanical protection during loaded tests. This motor uses a power-off holding brake. Forcing enable with brake locked will trigger stall alarm directly.

1. Visual & Mechanical Inspection (Power OFF, Priority)
2. Motor housing: Check for cracks, water/oil contamination, terminal box corrosion, bent/pushed-out pins or oxidation on connectors.
3. Cables: Power & encoder cables for damaged jacket, sharp bending, loose terminals. Separate routing for power and encoder cables; 360° shielding grounding.
4. Brake Inspection (Critical for this model)

Apply DC24V to brake terminals individually and verify pull-in/release sound. Brake locks when power removed.

After brake release, manually turn shaft: smooth rotation without sticking or friction noise. If still locked → brake mechanical seizure or coil damage.

Measure brake coil resistance: Normal value in tens of ohms. Open circuit = broken coil; near 0Ω = shorted coil.

❗ Brake is not for dynamic braking during operation; only standstill holding.

4. Bearing check: Manually rotate shaft, listen for rustling, squealing or metal friction noise. Check excessive radial/axial play or jerky rotation.
5. Coupling & load: Disconnect load and test motor standalone, to distinguish motor failure from mechanical jamming / misalignment.
6. Static Electrical Measurement (Power OFF, disconnect all cables from drive side)

Test object: Motor body, all cables disconnected

1. DC resistance of 3-phase windings (measure U/V/W pairwise)

Acceptance: Resistance deviation between 3 phases ＜5%, low resistance (milliohm range)

Abnormality: Infinite resistance on one phase = broken winding; unbalanced/lower resistance = inter-turn short; near 0Ω = phase-to-phase short.

2. Insulation resistance (500V megger)

Measure U, V, W to motor PE terminal. ≥1MΩ = acceptable; ＜0.5MΩ = moisture or insulation breakdown.

3. Encoder cable continuity: Check A, A-, B, B-, Z, Z-, power and ground wires one by one for open/short circuit; shield should be continuous.
4. Brake loop continuity: Measure brake coil resistance; verify brake wires not shorted to earth.

III. No-Load Commissioning (Load disconnected, V90 drive, V-ASSISTANT software)

1. Drive parameter verification: Motor model must be set to 1FL6042-2AF21-1AB1, encoder type: incremental 2500ppr.
2. Brake logic: Confirm brake terminal (11/12) outputs DC24V when drive enabled. Brake must be released before PLC/drive enable.
3. JOG no-load test

Motor runs smoothly without chattering, howling or overheating.

Monitor r0027 motor current: No-load current much lower than rated 4.7A. If no-load current close to rated → brake not fully released, winding fault or abnormal encoder feedback.

4. Encoder signal monitoring: Use V-ASSISTANT to check actual speed and position. Position should follow continuously during shaft rotation without dropout or jumping. Signal jumping → encoder, cable or EMI interference.
5. Frequently Occurring V90 Alarm Codes (Motor Related)

1. Targeted Troubleshooting by Symptom

1) JOG command, motor does not rotate, F7900 stall alarm

① Verify 24V brake output, manually confirm free shaft rotation; ② Check UVW phase sequence; ③ Disconnect load for test; ④ Measure 3-phase winding resistance balance; ⑤ Confirm correct motor model parameter.

2) Motor chattering, position drift, occasional position loss without fixed alarm

① EMC grounding, separate power and encoder wiring; ② Inspect encoder connector pins; ③ Isolated 24V control power supply, keep away from solenoid valves; ④ 360° shield grounding of cables; ⑤ Contaminated or damaged internal encoder code disc.

3) Overheating and overload alarm after short operation

① Bearing drag / partially released brake (brake dragging); ② Overloaded machinery; ③ Ambient temperature＞40℃; ④ Degraded winding insulation, minor inter-turn short.

4) Drive reports F30001 overcurrent immediately after power-up

① Power cable U/V/W shorted to earth or phase-to-phase; ② Motor winding phase-to-phase or earth breakdown; Do NOT repeatedly power on, to avoid further damage.

1. Acceptance Test for Second-hand / Used Motors
2. Visual inspection: Check flange and shaft for impact damage, deformed key, oil seal leakage.
3. Complete static resistance & insulation test.
4. Independent 24V brake test for pull-in/release, measure brake coil resistance.
5. 30min no-load JOG test, monitor current, temperature and vibration.
6. V-ASSISTANT encoder signal capture, continuous rotation test for stable position reading without jump.
7. Shaft runout measurement to assess bearing wear.
8. Cross-check nameplate against ordered part number.

VII. Troubleshooting Decision Logic (Quick Location)

1. Disconnect load → JOG works fine → Mechanical load fault
2. Still alarm after load removal → Disconnect motor power & encoder cables, test drive alone → If drive OK, fault is motor or cable
3. Fault persists after cable replacement → Motor body damage (winding / encoder / brake / bearing)

⚠️ Prohibited Operations

Do not apply continuous power to brake coil for long time; overheating will burn out the brake coil.

Do not repeatedly JOG with brake locked; risk of motor and drive power module damage.

Disconnect encoder cables fully before megger insulation test. High voltage will destroy encoder instantly.

Overload Capacity of 1FL6042-2AF21-1AB1 (V90 750W Low Inertia)

Rated Torque Mn: 2.39 N·m

Peak Torque Mmax: 7.20 N·m

Short-time Overload Ratio: Approx. 300% (3x)

Rated Current: 4.7 A

Peak Current: 14.2 A

✅ Key Notes

1. 300% is short-time peak capacity, not for continuous operation. Siemens V90 1FL6 uses drive I²t thermal model to limit overload duration:

300% overload is typically permitted for tens to hundreds of milliseconds, used for acceleration or impact loads. Sustained heavy overload triggers A7805 (I²t overheat warning).

Continuous operation must be ≤100% rated torque.

2. This overload rating applies to the combination of motor body and matched V90 drive. If drive is undersized, the achievable overload will be limited by the drive and cannot reach 3 times.
3. Available peak torque varies with speed: Full 7.2Nm peak torque is available up to rated speed 3000rpm. Peak torque drops in field-weakening region above rated speed.

📌 Selection & Commissioning Tips

Short acceleration / impact loads can utilize the 3x short-time overload; continuous load must be calculated based on rated torque 2.39Nm.

For vertical axes with brake, reserve safety margin in torque calculation. Do not use peak torque as continuous working torque.

The torque limit parameter in drive is defaulted within motor peak torque. It can be reduced according to mechanical safety requirements.