Troubleshooting OV Error in Inverters: Causes and Solutions

⚡ Inverter Overvoltage Error (OV): Causes and Solutions ⚡

Overvoltage (OV) is one of the most common faults in inverters, especially in systems with high-inertia loads such as cranes, coil unwinders in the steel or cable industry, or in environments with unstable power supply. If not handled properly, this error may cause sudden shutdowns, disrupt production, and shorten equipment lifespan.

🔍 On Parker drives, the overvoltage error codes appear as follows:

  • AC10: Displays error code OE
  • AC20, AC30, AC690: Displays Overvoltage

AC10 Inverter OE Overvoltage

📌 1. What is an Overvoltage Error?

Inverters use DC bus capacitors to store electrical energy. When the voltage on the DC bus exceeds the permissible threshold (typically > 400V for 3-phase 220V inverters, and > 800V for 3-phase 380V inverters), the inverter will trigger an overvoltage fault to protect the capacitors and power circuitry from damage.

⚠️ 2. Common Causes of Overvoltage

  • 🔁 High-inertia loads (motor stops too quickly):
    When the motor stops suddenly, mechanical energy returns to the inverter, causing a DC bus voltage spike.

    Common in: centrifuges, elevators, winders, long conveyors…

  • ⚡ Input voltage too high or unstable:
    Sudden spikes from the grid or unstable generator output
  • 🔧 Incorrect deceleration settings:
    Deceleration time too short, motor braking too abruptly

    No braking resistor or resistor with insufficient power rating

🛠️ 3. How to Fix Overvoltage Errors

  • ✅ Increase deceleration time:
    Adjust deceleration time to allow the motor to slow down gradually, limiting energy returned to the DC bus.
  • ✅ Install a braking resistor:
    Helps dissipate excess energy from the motor. Must be properly rated in both power and resistance.

    Note: Only applicable to drives with a built-in braking unit.

  • ✅ Check input voltage:
    Measure grid voltage to ensure it’s within allowable limits

    Use a voltage stabilizer if necessary

  • ✅ Set DC bus voltage limit (if supported):
    Parker AC10, AC20, AC30, and AC690 allow configuring DC voltage limits to protect internal circuits

💡 Practical Tips

  • If the error appears during motor stop: it’s likely due to fast deceleration or lack of braking resistor
  • If the error appears randomly during the day: check grid voltage – possible spike during peak hours
  • Braking resistors should be checked and maintained periodically to prevent failure or efficiency drop

📍 Summary

While overvoltage faults do not cause immediate damage, repeated occurrences can significantly shorten the lifespan of DC capacitors and power components. Identifying the correct cause and addressing it will help ensure system stability and extend the life of your drive and motor.