Resolving SINAMICS S120 Thermal Overload F30005 on SIMOTION D425

Overview

SIMOTION D425 motion controllers paired with SINAMICS S120 drive line modules are a common Siemens architecture for high-performance textile, packaging, converting, and printing machinery. The D425 (6AU1425-...) is a SIMOTION D-series controller that integrates an OPC, PROFINET IRT, and a SINAMICS S120 control unit (CU320-2) on the same backplane, exposing its drive axes via DRIVE-CLiQ to Motor Modules (e.g., booksize or chassis format). When the higher-level SIMOTION application runs on a machine built by an OEM that does not release the source project, engineers frequently face two interrelated problems:

1. Restoring the SIMOTION runtime (programs, technology objects, symbol tables, tasks) after a CF card failure or a controller swap.
2. Diagnosing drive-side faults such as thermal overload of the power unit, which on SINAMICS S120 surfaces as fault code F30005 (Power unit overload I²t) or F30004 (Power unit overtemperature), and tracing them back to gate-driver hardware such as the auxiliary transformer VAC5046X005.

This reference consolidates the field-proven procedure for loading a SIMOTION/SINAMICS project back to the engineering PG with SCOUT, explains the role of the "Store additional data on the target device" option, and walks through a real fault case where the root cause turned out to be a disconnected primary winding of the IGBT gate-driver transformer, not the motor or the load.

SIMOTION D425 + SINAMICS S120 System Topology

The D425 contains an embedded CU320-2 with a SIMOTION CPU. Drive axes are connected via DRIVE-CLiQ to Line Modules (Smart Line, Basic Line, or Active Line) and Motor Modules. The CF card slot on the D425 hosts both the SIMOTION runtime and the SINAMICS parameter image.

Field note: when the gate-driver auxiliary supply on the Motor Module drops out, the IGBTs do not switch cleanly. They spend excessive time in linear region, dissipating heat on the heatsink. The thermal model inside the SINAMICS then trips F30005, often making the operator (and SCOUT) suspect the wrong subassembly.

SCOUT Project Handling: "Load to PG" vs. "Download to Target"

SIMOTION SCOUT (now distributed as part of TIA Portal as SCOUT TIA, but historically standalone for V4.x and V5.x) provides two complementary operations against a connected controller:

Procedure: Backtransfer from a Running D425 to SCOUT

1. Connect the engineering PG to the D425 Ethernet port (X120/X130) and configure the PG/PC interface to the controller's PROFINET subnet.
2. Open the SCOUT project, right-click the D425 → Target system → Load → Load CPU / drive to PG.
3. Confirm the dialog: SCOUT first reads the SINAMICS topology online, then the SIMOTION runtime blocks. The progress window reports whether additional data was stored on the device.
4. After upload, verify completeness: open the project navigator. If Programs, Technology Objects, and Symbol browser show entries, backtransfer was complete. Empty branches indicate that the runtime was loaded without the additional-data flag.

The "Store Additional Data" Option — Why It Matters

When downloading a SIMOTION project to the D425, SCOUT offers a checkbox:

[x] Store additional data on the target device
    (recommended for service / backtransfer)

This flag causes SCOUT to write the SIMOTION source (ST, MCC, LAD/FBD sources, symbol table, TO configuration, alarm configuration) into the USER partition of the CF card in addition to the compiled runtime. The runtime alone is sufficient to execute the machine, but it is not round-trippable to a SCOUT source unless the additional data was stored.

Field consequence: in a 7-machine fleet from an OEM that does not release source, if the OEM downloaded with the option disabled, even a perfect CF card clone from a healthy sister machine will run but cannot be opened as a SCOUT source for editing. You must always ask the OEM for the SCOUT archive, or request that they re-download with "Store additional data" enabled during the next scheduled service window.

CF Card Cloning Across Machines

When projects cannot be sourced from the OEM, two cloning strategies remain:

1. Bit-image clone of the CF card — use a USB card reader and an imaging tool (Win32 Disk Imager, dd, or SIMATIC Automation Tool's card-image function). The clone includes the SIMOTION runtime, SINAMICS parameters, license keys, and any additional data that was originally stored. Suitable for identical hardware and identical axis configuration.
2. Topology-aware online copy — use SCOUT Load to file system on the healthy machine, then Download to target device on the failed machine, accepting the topology differences.

SINAMICS S120 Thermal Overload Fault Family

SINAMICS S120 distinguishes between thermal monitoring of the heatsink (sensor-driven, fast) and the I²t thermal model of the power unit (current- and time-driven, integrative). When the engineering team sees a "thermal overload power unit" message in SCOUT, they should resolve it in this order:

SCOUT Diagnostic Sequence for F30005

1. Open the drive online in SCOUT → Diagnostics → Fault buffer. Note the timestamp and additional information text. The exact wording "thermal overload power unit" maps to F30005.
2. Check r0036 / r0037 — power unit overload utilization. If this saturates at 100% within seconds of motion command, the I²t model is integrating faster than the application expects.
3. Inspect p0640 (current limit) and p0644 (overload threshold). On Motor Modules these are typically defaulted to 150% of rated current for 60 s; if the OEM has set them lower, the application can trip them under normal duty.
4. Read the heatsink temperature from r0037[0]. Compare to the trip threshold in p0290 (power unit overtemperature threshold). A normal heatsink temperature under load is 50–70 °C; if it climbs to 90 °C+ under no-load operation, the gate drivers are dissipating heat, not the motor.
5. Open the device online → Topology. Verify that all DRIVE-CLiQ components report OK status. A Motor Module reporting intermittent DRIVE-CLiQ errors may have lost its +24 V auxiliary supply feeding the gate drivers.
6. With the controller offline and the cabinet locked-out, measure the auxiliary supplies on the Motor Module per the SINAMICS S120 List Manual, Booksize section.

Hardware Root Cause: VAC5046X005 Gate-Driver Transformer

The Motor Module's IGBT gate-driver board receives its isolated +24 V / -15 V supplies from an auxiliary transformer mounted on the heatsink or on the driver PCB. On several booksize and chassis generations, this transformer is referenced as VAC5046X005 (or its successor part numbers). The secondary feeds a rectifier and filter network that includes a series-dropping resistor — typically 270 Ω — to set the gate-emitter reference voltage.

Why F30005 Instead of F30004

The heatsink sensor (NTC) reports the bulk thermal mass temperature. If the heatsink remains cool because the fan is operating but the gate drivers are starving, the heatsink temperature rises slowly and the I²t integrator (modeling instantaneous junction temperature from current × switching loss) trips first. This produces F30005 with a near-normal r0037[0] — confusing to operators who look only at the heatsink value.

Rewinding vs. Replacement

If the OEM part is unavailable and lead time is long, a competent winding shop can rewind the primary or secondary of VAC5046X005 provided:

• Original wire gauge and turns count are preserved.
• Inter-winding isolation class matches (typically Class B, 130 °C).
• The bobbin pinout is correctly remounted so the secondary polarity is preserved (reversed polarity destroys the IGBT gate by forward-biasing emitter-base).
• After rewind, the transformer is vacuum-impregnated to restore thermal conductivity to the core.

Thermal Stress and Component Lifespan

The reference case describes an inverter cooling arrangement where the fan is mounted only on the heatsink of the inverter, while the 270 Ω series resistor next to the gate-driver transformer dissipates additional heat into the same enclosure. Operating temperature rise above the rated ambient reduces component life according to the Arrhenius model:

L_op = L_rated × 2^{((T_rated − T_op) / 10)}

For electrolytic capacitors with a rated life of 10,000 h at 105 °C, every 10 °C of additional ambient temperature halves the service life. In an enclosure where the local hot spot reaches 75 °C instead of the rated 45 °C, the effective capacitor life drops by a factor of 2^{(105−75)/10} = 2³ = 8× — i.e. from 10,000 h to ~1,250 h of operating time before measurable degradation of the bulk capacitance. This drives the secondary fault pattern often observed weeks after the primary F30005 is cleared:

Field recommendation: relocate the cooling fan, or add an enclosure ventilation fan, so that the auxiliary transformer and its 270 Ω resistor share the same forced airflow path as the IGBT heatsink. Where possible, mount the resistor on a heatsink tab of its own.

SCOUT Diagnostic Parameters for Thermal Behavior

Commissioning and Verification Procedure

1. Power down the cabinet, lock out the main disconnect, wait the SINAMICS-specified discharge time (5 minutes minimum for booksize, longer for chassis).
2. Measure DC bus voltage at the Motor Module terminals with a properly rated meter. Confirm < 50 V before contact.
3. Open the Motor Module front cover. Visually inspect the gate-driver PCB, the auxiliary transformer (VAC5046X005), and the 270 Ω resistor for discoloration, cracked solder joints, or melted insulation.
4. Measure primary continuity of the transformer with a multimeter on ohms range. Compare to the schematic value (typically a few ohms to a few tens of ohms; open circuit = disconnected primary).
5. If open, either replace the transformer (preferred) or rewind per the procedure above. Reinstall, verify with ohms measurement.
6. Power up the cabinet. Watch the SINAMICS LED sequence on the Motor Module. A healthy module powers up to green within ~5 s. Red or flashing red indicates a residual fault.
7. Clear the fault buffer in SCOUT. Acknowledge F30005 (F30005 requires POWER ON acknowledgment unless p2101 is configured otherwise).
8. Run a no-load commissioning test of the axis with the motor uncoupled. Monitor r0036 and r0037. They should remain within the healthy ranges above.
9. Re-couple the load and run the OEM-defined test motion profile. Confirm that r0036 stabilizes below 60 % and r0037 below 75 °C.
10. Document the repair in the maintenance log, including the transformer part number, the failure mode, and the ambient temperature at the time of repair.

Troubleshooting Matrix

Preventive Maintenance Checklist

• Annual: clean the heatsink fins with compressed air (de-energized).
• Annual: verify fan operation and bearing condition; replace fans with audible bearing rumble.
• Every 2 years: thermal image of the cabinet while the machine runs. Compare to baseline. A 5 °C rise at the gate-driver transformer location is an early indicator of an open primary.
• Every 2 years: measure r0036 and r0037 at the OEM-defined test profile. Trend the values; a slow rise indicates capacitor aging.
• After any F30005 trip: do not simply acknowledge and run. Inspect the gate-driver hardware before the next production shift.
• CF card backup: schedule a quarterly Load to file system backup. Store at least two generations offline, with the date and machine serial number in the filename.

Multi-Machine Fleet Considerations

Operating a fleet of identical machines (e.g., the 7-machine textile fleet in the reference case) is the textbook scenario where SCOUT project management discipline pays off:

1. Designate one machine as the reference. Maintain a SCOUT archive for it.
2. Whenever the OEM performs a software update, request that they re-download with "Store additional data" enabled, or have them provide an updated SCOUT archive.
3. After any service intervention, back up the CF card image of the affected machine before re-energizing.
4. Use SCOUT Compare projects to verify that all machines in the fleet have identical runtime. A divergence indicates that one machine has been edited in place.

Verification: Has the Repair Worked?

After the gate-driver transformer repair, the following acceptance criteria indicate success:

1. SINAMICS powers up to green state within 5 s.
2. F30005 does not reappear in the fault buffer after 8 hours of normal production duty.
3. r0036 stabilizes below 60 % during the heaviest motion profile.
4. r0037 stays below 75 °C during continuous operation.
5. The 270 Ω resistor is cool to the touch (or only slightly warm) within 2 minutes of motion stop. If it is hot enough to be uncomfortable, the gate-driver bias is still abnormal and the repair is incomplete.
6. The enclosure interior temperature, measured 10 cm from the Motor Module, is at most 10 °C above the cabinet inlet temperature.

FAQ