What is f30002 fault in siemens drive?

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Getting a F30002 fault on your Siemens G120 or S120 drive? Learn why the DC link voltage is spiking and how to fix it using braking resistors or ramp adjustments.

What is f30002 fault in siemens drive?

 

Siemens F30002: When Your DC Link Is Under Pressure

If you are working with Siemens SINAMICS drives (like the G120 or S120), F30002 is a code you will eventually encounter. In the Siemens ecosystem, this translates to: DC link overvoltage.

Essentially, the "internal reservoir" of DC power inside the drive has filled up past its safety limit. If the drive didn’t trip, the capacitors could physically fail—often with a loud pop and a cloud of smoke.

Here is a technical breakdown of why this happens and how to clear it.

The Physics: Why Does the Voltage Spike?

The DC link voltage is roughly . For a 400V supply, your DC link sits around 540V DC. The F30002 fault usually triggers when this climbs toward 800V or 900V (depending on the drive rating).

The main culprit? Regenerative Power. When a motor slows down a heavy load faster than it would naturally coast, the motor turns into a generator. It pushes energy back into the drive. Since the drive’s input bridge is a "one-way street," that energy has nowhere to go but the DC link capacitors, causing the voltage to skyrocket.

Common Causes of F30002

  1. Ramp-down time is too short: You’re trying to stop a massive fan or high-inertia flywheel in 2 seconds when it needs 20.

  2. Braking Resistor issues: You have a braking resistor installed, but the fuse is blown, the wiring is broken, or the resistor itself is open-circuit.

  3. High Line Voltage: If your factory's incoming AC power is running too high (overvoltage on the grid), the DC link starts at a higher baseline, leaving less "room" for regenerative energy.

  4. Vdc_max Controller is disabled: Siemens drives have an internal software feature to automatically extend ramp times to prevent this fault, but it can be turned off (Parameter p1240).

The Troubleshooting Checklist

Step 1: Check the Mechanics

Is the load "pushing" the motor? This is common in cranes (hoisting down) or downhill conveyors. If the load is overhauling the motor, you must have a way to bleed off that energy.

Step 2: Inspect the Braking Resistor (If applicable)

  • Measure Resistance: Disconnect the resistor and check it with a multimeter. It should match the Ohms printed on the nameplate.

  • Check the Chopper: Ensure the Braking Module (the switch that sends power to the resistor) is actually activating.

Step 3: Adjust Parameters in TIA Portal / Starter

  • Increase p1121: Lengthen the deceleration time. Even adding 2–3 seconds can make the difference.

  • Enable p1240: Set the Vdc_max controller to "1" (Enable). This tells the drive: "If the voltage gets too high, ignore my ramp-down command and slow down more gradually to stay safe."

 

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