Cause : Overvoltage at constant speed comes when the DC bus voltage has exceeded the allowable limit while the motor is running at a steady speed.

"E07.01" fault in inovance MD800 drive indicate " Overvoltage at constant speed". Unlike during acceleration or deceleration, this fault is less common and typically points to issues related to power supply instability, regenerative energy from the load, or drive/motor malfunctions.

Possible Causes:

1. Power Supply Instability: Voltage spikes or fluctuations in the power supply can cause the DC bus voltage to rise unexpectedly.
2. Regenerative Energy from the Load: Even at constant speed, certain loads with high inertia or varying resistance can generate regenerative energy that the drive must dissipate.
3. Incorrect Drive Settings: Improper parameter settings, such as those for voltage limits or control modes, can lead to overvoltage conditions.
4. Braking Resistor Issues: If the braking resistor is undersized, faulty, or not correctly installed, the drive may be unable to dissipate regenerative energy.
5. Motor or Drive Fault: There could be an issue with the motor or drive, such as a malfunctioning component that leads to abnormal voltage levels.

Troubleshooting Steps:

1. Check Power Supply Stability:

   • Monitor the power supply for any signs of instability, voltage spikes, or fluctuations. Ensure that the supply voltage is within the specified range for the drive.
   • Consider using a line reactor, voltage stabilizer, or other power conditioning equipment to smooth out any irregularities in the power supply.

2. Evaluate the Load:

   • Analyze the load to determine if it might be generating regenerative energy, even at a constant speed. High-inertia loads or loads with varying resistance could contribute to overvoltage.
   • If the load is contributing to regenerative energy, ensure that the drive's braking resistor or dynamic braking system is adequate to handle the excess energy.

3. Inspect and Size the Braking Resistor:

   • Verify that a braking resistor is installed and is correctly sized to dissipate any regenerative energy. If the resistor is undersized or not functioning, replace it with an appropriate unit.
   • Ensure that the braking resistor is properly connected and that its wiring is intact.

4. Review and Adjust Drive Settings:

   • Check the drive's parameters related to DC bus voltage limits, braking, and control modes. Incorrect settings can lead to overvoltage conditions.
   • Adjust the parameters to ensure that the drive can handle any regenerative energy without exceeding the voltage limits.

5. Inspect the Motor and Drive:

   • Check the motor for signs of damage, such as insulation breakdown, winding issues, or other faults that might cause abnormal voltage levels.
   • Inspect the drive for potential issues, such as malfunctioning components (e.g., IGBT modules, capacitors) that could lead to overvoltage.
   • Test the motor with another drive or the drive with another motor to isolate the problem.

6. Enable Overvoltage Protection Features:

   • If available, enable or adjust the drive's overvoltage protection features to better handle any regenerative energy during constant speed operation.
   • Consider setting up dynamic braking or a chopper circuit if your application generates frequent regenerative energy.