Undervoltage Fault at Deceleration in a drive indicates that the drive has detected a voltage level lower than its minimum allowable limit during the deceleration phase of motor operation. This type of fault typically occurs when the drive is slowing down the motor, and it can result from various issues related to voltage, power supply, or system configuration.

Common Causes of Undervoltage Fault at Deceleration:

1. Power Supply Issues:

   • Voltage Drops: During deceleration, the power supply might not be able to provide the required voltage, leading to undervoltage conditions. This can be due to insufficient power supply capacity or poor quality of the power supply.
   • Input Voltage Imbalance: An imbalance or drop in the input power phases can cause undervoltage faults.

2. Drive Configuration and Settings:

   • Improper Deceleration Settings: Incorrectly configured deceleration ramps or parameters can lead to undervoltage conditions. If the drive is not set to handle the changes in load or energy correctly during deceleration, it might experience undervoltage.
   • Inadequate Voltage Settings: If the drive's voltage settings are not correctly configured, it may not handle the voltage requirements during deceleration properly.

3. Regenerative Braking Issues:

   • Regenerative Energy Absorption: During deceleration, if the motor is generating regenerative energy, and the drive or braking system is not equipped to absorb or manage this energy effectively, it can lead to undervoltage faults. This might be due to insufficient regenerative braking capability or problems with braking resistors.

4. Faulty Motor or Wiring:

   • Motor Insulation Problems: Issues with motor insulation can cause excessive current draw or voltage irregularities, leading to undervoltage conditions.
   • Cable Issues: Damaged or poorly connected cables can cause voltage drops or irregularities.

5. Drive Component Issues:

   • Component Failure: Failures in drive components, such as power transistors (IGBTs) or capacitors, can lead to incorrect voltage levels and trigger faults.
   • Internal Faults: Internal faults within the drive’s circuitry may result in undervoltage conditions.

Troubleshooting Steps for Undervoltage Fault at Deceleration:

1. Check Fault Codes:

   • Review the fault codes on the drive’s display to confirm that the issue is related to undervoltage during deceleration. Consult the drive’s manual for details on the fault code and its meaning.

2. Inspect Power Supply:

   • Measure the input voltage to the drive to check for stability and any drops or imbalances. Ensure that the power supply is providing consistent and adequate voltage.
   • If voltage drops are detected, consider using a power conditioner or addressing any issues with the power supply.

3. Review Drive Configuration:

   • Check and adjust the deceleration settings in the drive’s parameters. Ensure that the deceleration ramp and other settings are properly configured for the motor and application requirements.
   • Verify that the voltage settings are appropriate for your application and ensure the drive can handle the voltage requirements during deceleration.

4. Examine Regenerative Braking System:

   • If the drive uses regenerative braking, check its operation and ensure it is functioning correctly. Verify that the system can handle the regenerative energy generated during deceleration.
   • Consider adding or upgrading dynamic braking resistors if needed to manage regenerative energy.

5. Inspect Motor and Wiring:

   • Check the motor for insulation problems or damage. Use a megohmmeter to test insulation resistance and ensure it is within acceptable limits.
   • Inspect cables and connections for damage or poor connections that could cause voltage drops. Repair or replace damaged cables as needed.

6. Check for Electrical Interference:

   • Investigate sources of electrical noise or interference in the environment. Use shielding or proper grounding to minimize interference.