Commissioning Third-Party Motors on SINAMICS S120 with SMC10

Overview

Commissioning a third-party (non-Siemens) motor on a SINAMICS S120 Motor Module through the SMC10 Sensor Module is a defined workflow that combines data-sheet entry, sensor module parameterization, and automatic motor data identification. The challenge is that third-party vendors often supply only the rated nameplate values (voltage, current, speed, torque) and a pole-pair count, leaving the integrator to derive everything else.

The most common third-party machine in this application class is a low-speed, high-pole-count, hollow-shaft torque motor - structurally and electrically similar to the Siemens 1FW6 SIMOTICS T built-in torque motor. Such machines almost always use a multipole resolver as the commutation reference because absolute encoders would be impractical across the 14-56 pole-pair range that these motors span.

This guide walks through the complete commissioning path, including the parameter-by-parameter STARTER wizard entry, the resolver pole-pair verification technique, the protection of encoder data against STARTER overwrites, and the verification methodology using the r0061 / r0063 speed comparison.

Prerequisites

Before starting the commissioning wizard, assemble the following. Missing items prolong commissioning and increase the risk of saturation or instability during the identification run.

Software and firmware:

• STARTER (Startdrive alternative) version V5.5 or later with the appropriate Drive ES package for the S120 firmware in use (typically V5.2 / V5.3 for current S120 control units CU320-2 and CU310-2).
• Device description (GSD/GSDML or STARTER object list) consistent with the Control Unit firmware.
• Latest Technology Extensions if the drive is enabled for firmware-based feature packs.

Hardware Topology and Signal Flow

The resolver feedback is connected from the third-party motor to the SMC10 Sensor Module via the 15-pin sub-D connector X520. The SMC10 sits on the DRIVE-CLiQ bus as a slave and is auto-recognized by the Control Unit once commissioned. The Motor Module (Line Module → DC link → Motor Module → motor) receives the controller's voltage commands based on torque/speed setpoints processed in the CU320-2.

When commissioning, the closed-loop chain must be:

1. Commanding speed/torque setpoint generated in the CU320-2 from PROFIBUS / PROFINET or terminal setpoints.
2. Current controller in the Motor Module executing at the S120 current-loop rate (typically 8 kHz / 4 kHz depending on p0115).
3. Speed feedback read from SMC10 (resolver decode) and fed to the speed controller.
4. Commutation angle p0431 applied to the field-orientation so that current is in the d/q frame of the rotor.

The third-party motor in question is mechanically compatible with the 1FW6 family (hollow shaft, integrated water jacket or natural convection). The electrical parameters, however, must be entered exactly. Treat the 1FW6 default parameters in STARTER only as a sanity check; they are not a valid substitute for the actual machine data.

Motor Parameterization in the STARTER Wizard

Open the project in STARTER, navigate to the drive object, and call up the configuration dialog. The wizard presents the parameter groups in the order below; do not skip groups even if data appears redundant - some parameters become accessible only after prerequisites are set.

Drive configuration

• p0100 = 0 (Europe, 50 Hz line) or 1 (N. America, 60 Hz line) - depends on the rated voltage class of the Motor Module, not the line input.
• p0200 = 1 (confirm Motor Module type) - the wizard auto-detects from DRIVE-CLiQ.

Motor nameplate parameters

Calculated equivalent circuit data

After the nameplate data is committed, STARTER computes p0350 (stator resistance, cold), p0356 (stator leakage inductance), and p0360 (magnetizing inductance) using the Siemens standard three-phase model. For a third-party motor these are starting points only; they will be replaced by the values measured in the stationary and rotary identification runs.

Resolver Configuration on the SMC10

The SMC10 supports two-pole and multipole resolvers. The resolver pole-pair number must match the motor pole-pair number for the commutation to be correct. A mismatch of 1:1 versus 1:2 is the single most common commissioning error with SMC10 on third-party torque motors.

Identifying the resolver pole-pair number when undocumented

If the resolver datasheet is not available (a common case with Smartsyn resolvers from a third-party motor), the following procedure derives the pole-pair number by comparing the electrical and mechanical revolution counts. The SMC10 reports the electrical angle via r0094 (transformer flux angle, 1 rev = 1 electrical cycle per pole pair) and the mechanical angle via r0413[0] (mechanical position).

1. Disable all speed/current controllers, switch the drive to "no pulses enabled" (commissioning mode).
2. Apply a small open-loop current in the field direction (set p1501[0] to a positive torque direction with no current, or use p1545 current setpoint) to lock the rotor magnetically - some resolvers can be characterized open-circuit, but locking improves signal integrity.
3. Rotate the shaft by hand exactly one mechanical revolution (mark the shaft and the housing with a fine pen).
4. Observe the value of r0094. The number of full cycles accumulated in one mechanical revolution equals the resolver pole-pair number.

If r0094 advances by 14 cycles per mechanical turn, the resolver is matched 1:1 with the motor (poles of motor = poles of resolver) and p0425[0] = 14. If the ratio is 7 cycles per mechanical turn, the resolver is a 7-pole-pair device and the motor has 14 pole pairs - this is mechanically valid but the commutation mapping in the drive will interpret it as a different electrical angle per mechanical revolution, producing a fault on first rotation. Confirm the manufacturer's drawing before forcing a 1:2 relationship.

Stationary and Rotary Motor Identification

After the basic parameters are written to the drive, STARTER offers the automatic identification routine. Run it in the order: stationary first, then rotary. The rotary measurement requires the motor to be unloaded (no gearbox output, no load inertia coupled) or loaded only by a known moment of inertia that has been entered into p0341.

Stationary measurement (p1910)

The stationary measurement is a low-speed saturation test. The drive injects a controlled current at zero speed and ramps through the magnetic operating point to identify:

• Stator resistance p0350 (cold)
• Leakage inductance p0356
• Magnetizing / main field inductance p0360
• Saturation characteristic p0362...p0369 for current controller gain adaptation

Set p1900 = 2 (stationary only) and trigger via the STARTER "Measure" button. Allow at least 60 seconds for the drive to ramp and settle. The motor may emit an audible single-tone hum during the test - this is normal.

Rotary measurement (p1960)

Once stationary data is in place, run the rotary measurement with the motor uncoupled from the load. The drive commands a controlled acceleration, holds at a safe speed (typically 20-50% of rated), and optimizes:

• Speed controller gain p1460 (Kp) and integral time p1462 (Tn)
• Field-weakening characteristic if the machine will run above rated speed
• Inductance saturation curve used for the Kp adaptation table

Set p1900 = 1 (full identification with rotary), confirm the safety circuit is closed and an enable is on the drive, and start. The drive will spin the motor in the positive direction first, then negative - monitor the speed actual value r0063 live in the trace to confirm smoothness.

Encoder Data Protection During Identification

This is the single most important safeguard. STARTER calculates a proposed number of "encoder pulses per revolution" based on the resolver sample rate and the motor pole-pair number. The proposed value is mathematically plausible but is rarely correct for a resolver - because a resolver does not have PPR in the optical-encoder sense, the drive synthesizes a virtual pulse count that should be left at 1 for an unmultiplied resolver or set to the manufacturer's recommended virtual value if the drive firmware requires a non-unity number for the position controller interface.

1. Before clicking "Accept" on the rotary measurement results, scroll to the Encoder data summary.
2. Note each proposed value (p0408, p0425, p0410, p0431) alongside the values you entered at the start of commissioning.
3. Copy / paste the original values over each proposed value. Do not let the wizard overwrite them.
4. Accept the motor equivalent-circuit and controller parameters, but reject the encoder parameter substitution.

The same protection applies to p0431 (commutation angle offset). The drive's automatic commutation will compute an angle during the first few rotations of the rotary test; this should be checked against the value the drive computed automatically (typically stored in r1774 during p1980). If the drive repeatedly overwrites p0431 on each power-up, freeze it by setting p1990 = 1 (encoder adjustment: do not accept new commutation offset).

Encoder Speed vs. Calculated Speed Verification

The cleanest field verification of correct resolver mapping and motor parameterization is the dual-speed comparison. Run the drive in encoderless mode for a short ramp, then in sensor mode, and overlay the two actual speeds:

• r0061 = actual speed, encoderless (model-based EMF observer)
• r0063 = actual speed, encoder feedback

1. Set p1300 = 20 (encoderless, with sensor) or use the STARTER control panel to toggle.
2. Command a 0 → 50% rated speed ramp over 5 s.
3. Open STARTER's trace, sample r0061 and r0063 at 1 ms, plot overlaid.
4. Both signals must have the same sign (positive when commanded positive) and agree within ±5% steady state. Disagreement under 5% reflects model noise; larger divergence indicates wrong p0410 inversion, wrong pole-pair number, or wrong p0310.

The two signals will not match instantaneously because the encoderless observer has a low-pass characteristic and the encoder is sampled at the speed-controller cycle. Use a 2-3 second steady-state window for the comparison.

Cable Resistance, Length, and Ambient Temperature Compensation

The default 20 °C ambient temperature and 0.0 Ω motor cable resistance are placeholder values. Replace them before identification so the measured p0350 reflects only the motor:

For a 25 m, 4 mm² copper motor cable, the per-kilometer resistance is approximately 4.5 Ω/km; the total per-phase resistance of the loop is 2 × 25 m × 4.5 Ω/km × 0.001 = 0.225 Ω. This is significant in low-impedance torque motors and is required to avoid an over-current fault during the saturation sweep of the stationary identification.

Shielding, Bonding, and EMC Requirements

For third-party motors, the resolver cable shielding is the single most common source of encoder faults in field service. The Siemens third-party motor system manual specifies:

• Apply the shield at both ends, as close to the SMC10 module and as close to the motor terminal box as practicable.
• Use a 360° circumferential connection (EMC backshell, P-clip, or cable gland with shield ring), not a pigtail.
• Route the resolver cable and motor power cable in separate trays with at least 200 mm physical separation, or use a partitioned tray.
• Bond the motor frame to the cabinet backplane with a short, large-cross-section strap (≥ 10 mm², length ≤ 200 mm).
• Use a continuous, double-shielded cable (overall + pair) for the resolver to maximize rejection of the inverter common-mode voltage.

Failure to meet these requirements typically manifests as a fault on first commissioning, then on hot restarts, and finally as a speed ripple that tracks the inverter switching frequency. See the linked Siemens third-party motor system manual for the full EMC compliance diagram.

Troubleshooting Matrix

Verification Checklist Before Handover

1. STARTER project has the as-built parameter set committed, with a project archive saved to the project document server.
2. STARTER trace shows r0061 and r0063 overlaid, agreeing within ±5% across a 0 → rated speed ramp and back.
3. p0431 commutation offset locked (p1990 = 1) unless there is a documented reason to permit re-detection.
4. Thermal model disabled for the third-party motor (p0612 = 0) or used only with a vendor-supplied temperature sensor.
5. Resolver cable shield verified at both ends; motor frame bonded to cabinet ground.
6. Drive is fault-free on cold start, hot start, and line-loss recovery.
7. Motor nameplate is photographed and stored in the asset record, with all entered p03xx parameters traceable to the source data point.

Field-Proven Tips for Third-Party Torque Motors

Third-party torque motors paired with the S120 drive family typically outperform the same motors paired with a vendor-supplied drive, because the S120 current loop bandwidth and the resolution of the speed controller are generally well above the machine's electrical time constant. The downside is that this same bandwidth exposes any error in the equivalent-circuit data or in the resolver mapping, so the diagnostic steps above are non-negotiable.

Specific tips from the field:

• When the resolver data sheet is unavailable, measure the resolver pole-pair number using the r0094 manual-rotation test described above. Do not assume the resolver and motor share the same pole-pair number; the industry is split between 1:1 (preferred for commutation simplicity) and 1:2 (used for cost reasons in lower-performance machines).
• For water-cooled torque motors, set p0335 = 2 and ensure the p0612 thermal model uses a water-flow factor from the manufacturer's cooling diagram, not the air-cooled default.
• If the third-party motor has a non-Siemens terminal box with a wiring colour code that is not the SINAMICS standard, document the cross-reference and laminate it inside the cabinet door. This reduces Mean Time to Repair on field service calls.
• Always keep the original STARTER project file (and a .dmp parameter export) for at least the warranty period; third-party motor commissioning is the kind of work that is rarely re-run by the same person.