F30011 — Power unit: Line phase failure in main circuit

F30011 is raised when, at the power unit, the DC link voltage ripple has exceeded the permissible limit value. The drive reports this condition under the title “Power unit: Line phase failure in main circuit”, but the ripple can have several root causes besides a genuinely failed line phase — the list below follows the manual.

• A line phase has failed.
• The 3 line phases are inadmissibly asymmetrical.
• The capacitance of the DC link capacitor forms a resonance frequency with the line inductance and the reactor integrated in the power unit.
• The fuse of a phase of the main circuit has ruptured.
• A motor phase has failed.
• Where the manual describes the S120/S150 power units there is one further possible cause: for power units operated on a single phase, the permissible active power was exceeded.

1. Check the main circuit fuses.
2. Check whether a single-phase load is distorting the line voltages.
3. If the cause is the resonance between the DC link capacitance and the line inductance, detune the resonant frequency by using an upstream line reactor.
4. Alternatively, dampen the resonant frequency by switching over the DC link voltage compensation in the software (p1810) or by increasing the smoothing (p1806). The manual warns that this can have a negative impact on the torque ripple at the motor output.
5. Check the motor feeder cables.
6. For the G115D the short fault table condenses the remedy to: check the line cables. For the G120C it says: check the motor cables.

• The drive stores the fault value in r0949, to be interpreted as a decimal number.
• The manual gives no decoding for on-site use; it states: Only for internal Siemens troubleshooting.

• r0949 — holds the fault value of this message (read as decimal); the manual reserves it for internal Siemens troubleshooting, so it does not help with on-site diagnosis.
• p1810 — used to switch over the DC link voltage compensation in order to dampen the resonant frequency with the line inductance.
• p1806 — increasing this raises the smoothing; the manual notes the possible negative impact on the torque ripple at the motor output.

The drive reacts with OFF2 (OFF1), so the drive coasts down and stays off until the fault has been cleared; the message is acknowledged IMMEDIATELY. Eliminate the cause first, then acknowledge the fault and restart the drive.