SINAMICS S120 Fault F30005 — Power Unit I2t Overload

Overview

The F30005 Power Unit I2t Overload fault indicates that the thermal load capacity limit of the SINAMICS S120 power unit has been exceeded. This safety mechanism is mathematically calculated based on the squared current output integrated over time ($I^2t$), protecting the internal insulated-gate bipolar transistors (IGBTs) from permanent thermal destruction. Unlike an absolute overcurrent fault which trips instantaneously, the F30005 fault triggers when continuous or cyclic operating conditions heat the power semiconductors beyond their rated operating threshold.

At its core, the drive's internal algorithm monitors the current flowing through major components and estimates the junction temperature of the silicon dice inside the IGBT modules. When the calculated utilization parameter reaches 100%, the drive initiates a shutdown sequence to prevent total hardware failure.

Symptoms

When a SINAMICS S120 experiences this thermal overload condition, maintenance personnel will typically observe several of the following physical and system behaviors:

• Active Fault Code F30005: The fault is displayed on the Operator Panel (BOP20 or AOP30) or indicated in engineering software platforms such as STARTER, Startdrive, or TIA Portal.
• Prior Warning Alarm A30005: Under normal configurations, the drive generates a warning alarm (A30005) before reaching the trip threshold. This is a crucial early observation indicating that the thermal utilization has surpassed the warning threshold (typically set around 80% to 90% load).
• Sudden Drive Tripping during High Acceleration: The system operates normally at steady-state velocities but trips as soon as it attempts an aggressive dynamic move or acceleration ramp.
• High Heatsink Temperatures: The actual measured temperature values within parameters such as r0037 show elevated values nearing the physical limits of the system.
• Forced Machine Downtime: Once the unit trips, it cannot be immediately reset. Modern S120 drives require a physical cooling period before allowing a fault acknowledgment to clear.