How to Fix Siemens V20 Fault F1 Overcurrent Troubleshooting

Getting an F1 Overcurrent fault on your Siemens Sinamics V20? Learn how to identify motor shorts, mechanical jams, and parameter errors to clear the fault.

 

How to Fix Siemens V20 Fault F1: Overcurrent Solutions

If your Siemens SINAMICS V20 has just tripped with Fault F1, it means the drive’s output current has exceeded its safe limit. Because this fault can be caused by anything from a loose wire to a seized motor, it can be intimidating to diagnose.

In this guide, we will look at the three main areas to investigate: Wiring, Mechanics, and Parameters.

What Does Fault F1 Actually Mean?

The F1 fault is a protective "shield." The drive's internal transistors (IGBTs) can only handle a certain amount of current before they sustain permanent damage. When the drive "sees" a massive spike or a sustained current draw above its rating, it cuts power instantly to save itself and your motor.

Common Causes of F1 on the V20

• Motor Short Circuit: A failure in the motor windings or the cable insulation.
• Ground Fault: Electricity is "leaking" from one of the phases to the earth/ground.
• Mechanical Jam: The machine the motor is turning is stuck, causing the motor to pull massive current to try and break free.
• Acceleration Too Fast: You are trying to get a heavy load up to speed too quickly.
• Parameter Mismatch: The motor data in the drive doesn't match the actual motor connected to it.

Step-by-Step Troubleshooting for F1

1. The "Isolation" Test

Before you blame the drive, we need to know if the problem is in the motor or the V20.

• Disconnect the motor wires from the drive terminals (U, V, W).
• Try to run the drive without the motor connected.
• If F1 still appears: The drive's internal hardware is likely damaged.
• If F1 disappears: The problem is in your motor or cables.

2. Check Your Cables and Motor

Use a multimeter (or a Megger if you have one) to check for:

• Phase-to-Phase Shorts: Ensure there is no continuity between U-V, V-W, or U-W.
• Phase-to-Ground Shorts: Ensure no phase is touching the motor frame or ground wire.
• Moisture: Check the motor terminal box for water or oil, which often causes F1 trips in humid environments.

3. Review Parameter P0305 (Motor Current)

Check Parameter P0305 on your keypad. This must match the Rated Amps on your motor nameplate. If this value is set too low, the drive will be "over-sensitive" and trip F1 even if the motor is doing nothing wrong.

4. Lengthen the Acceleration Time (P1120)

If the F1 fault only happens right when the motor starts moving, your Ramp-up time might be too short.

• Go to Parameter P1120 and increase it (e.g., from 10 seconds to 20 seconds). This gives the drive more time to overcome the load's inertia without a massive current spike.

Mechanical Check: The "Free Spin" Test

Sometimes the electrical system is perfect, but the machine is stuck. Turn off the power and try to rotate the motor shaft by hand (or with a wrench). If it feels unusually stiff or won't move at all, your F1 fault is actually a mechanical bearing failure or a jam in your machine.

How to Reset Fault F1

1. Fix the underlying short circuit or mechanical issue.
2. Press the Fn (Function) button on the V20 keypad to clear the fault.
3. If the fault is caused by high heat along with the current, you may need to wait 1-2 minutes for the internal components to cool before it will allow a reset.

Summary

The Siemens V20 F1 fault is serious but solvable. By isolating the motor from the drive, checking your P0305 current settings, and ensuring your machine isn't physically jammed, you can identify the cause of the overcurrent and get back to work.