VFD Overcurrent Fault: Common Causes and How to Fix It

An Overcurrent (excess current) fault is one of the most common errors that stop inverters in factories. It appears when the inverter senses that the current supplied to the motor has exceeded the allowed limit, so it trips immediately to protect itself and the motor. Sometimes the cause is simple, such as an incorrect setting, and sometimes it is an internal fault in the inverter that requires repair. In this article we explain, from the experience of our lab in Riyadh, how to identify the cause and act correctly.

How does the overcurrent fault appear in different brands?

Each manufacturer displays the fault with a different code. Common examples include:

• Siemens: F0001 in MICROMASTER, and F30001 in SINAMICS
• ABB: Overcurrent (code 2310 in the ACS580 series)
• Schneider Altivar: OCF
• Mitsubishi: E.OC1 / E.OC2 / E.OC3 (during acceleration / constant speed / deceleration)
• Delta: ocA / ocn / ocd
• Yaskawa: oC
• Danfoss: Alarm 13 Over Current

Note: Codes vary by model, so always refer to your inverter's catalogue.

Common causes of an overcurrent fault

1. 1. Acceleration or deceleration time too short: the inverter tries to ramp the motor speed faster than the load allows.
2. 2. Motor or cable fault: short between phases or ground leakage (Ground Fault) due to insulation damage or moisture.
3. 3. Excess or jammed mechanical load: worn bearings, an overtightened belt, or a part stuck in the machine.
4. 4. Incorrect motor settings: motor data is wrong or Auto-Tuning was not performed.
5. 5. Opening or closing a contactor on the inverter output while it is running.
6. 6. Cables too long between the inverter and the motor without a suitable output filter.
7. 7. Internal inverter fault: failed IGBT transistors, a driver circuit fault, or a current sensor fault.

Inspection steps before calling a technician

⚠️ Safety warning: Disconnect the power and wait until the DC Bus capacitors are fully discharged (usually 5 to 15 minutes depending on the model) and verify with a multimeter before touching any terminal.

1. 1. Record the code and when it appears: does it occur at start-up, during acceleration, at constant speed, or during stopping? This identifies the type of problem.
2. 2. Disconnect the motor cable from the inverter and test the insulation of the motor and cable with a Megger.
3. 3. Check the mechanical load: does the motor turn freely by hand?
4. 4. Review the acceleration and deceleration times and the motor data, and run Auto-Tuning if the model supports it.
5. 5. If the inverter shows the same fault even with the motor disconnected (on models that allow no-load operation), the problem is most likely inside the inverter itself.

When does the inverter need lab repair?

• The fault appears even without a motor
• There is a burning smell or heat marks on the inverter
• The inverter will not start at all after the fault
• The fault recurs despite the motor, cables and settings being fine

In these cases the fault is usually in the IGBT module, the driver board, or the current sensors, which requires component-level repair and load testing.

Inverter repair at the Rawad Alatmata lab

At our lab in Riyadh (Al-Dar Al-Baida – Al-Yaqout Road) we repair inverters of all brands at component level, and load-test every unit on a motor before delivery.

• Free diagnosis and free quotation
• Urgent repair within 1 to 2 working days
• Warranty up to 8 months

Learn more about our inverter repair service: VFD & Inverter Repair

Frequently Asked Questions