Siemens SINAMICS F0002: Managing the DC Link Overvoltage

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Troubleshooting the F0002 fault on Siemens Micromaster and SINAMICS drives. Learn how to fix overvoltage issues caused by regenerative energy and ramp settings.

Siemens F0002: When Your Drive Has Too Much Energy

If your Siemens drive (particularly the classic Micromaster series or certain SINAMICS modules) stops with an F0002 fault, it’s telling you one thing: the DC Link Voltage has exceeded the trip level.

Think of the DC link as a battery inside the drive. If that "battery" gets overcharged, the drive trips to prevent the internal capacitors from exploding.

Why does F0002 happen?

This is almost always related to Regenerative Energy. When you try to slow down a motor, it acts like a generator and pushes power back into the drive. If the drive can't get rid of that power fast enough, the voltage rises.

1. Deceleration Ramp is Too Short

This is the most common cause. You are trying to stop a high-inertia load (like a large fan or a heavy flywheel) too quickly. The motor generates more power than the drive's internal capacitors can soak up.

2. Overhauling Load

If the motor is being "driven" by the load—such as a gravity-fed conveyor or a hoist moving downward—it is constantly generating power back into the DC link.

3. High Input Supply Voltage

If your factory's incoming AC power spikes or is consistently too high, the DC link starts at a higher baseline level, leaving very little room for any regenerative energy before hitting the trip point.

4. Missing or Broken Braking Resistor

If your application requires a braking resistor to burn off excess energy and that resistor is disconnected, burnt out, or the "chopper" circuit is disabled, F0002 is inevitable.

The Troubleshooting Checklist

Step 1: Check the Ramp-Down Time

The first and easiest fix is to give the motor more time to stop.

  • Increase parameter P1121 (Deceleration time). If it’s currently set to 5 seconds, try 10 or 15 seconds.

Step 2: Monitor the DC Link Voltage

Watch the actual voltage while the drive is running and during the stop command.

  • Check parameter r0026 (Actual DC link voltage).

  • For a 400V drive, the trip usually happens around 800V DC. If you see it climbing rapidly during deceleration, you've found your problem.

Step 3: Enable the Vdc_max Controller

Siemens drives have a built-in "safety" feature that automatically slows down the deceleration if the voltage gets too high.

  • Check P1240. Set it to 1 to enable the Vdc_max controller. This is a "quick fix" that prevents the trip by extending the ramp automatically.

Step 4: Inspect Braking Hardware

If you have a braking resistor:

  1. Check the resistance with a multimeter (ensure power is off and DC bus is discharged!).

  2. Ensure it matches the value required by the drive manual.

  3. Check the wiring for any loose connections or blown fuses.

 

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