Overvoltage Due to High Mains Voltage

What does Overvolt mean?

This fault indicates that the incoming mains supply voltage has risen above the VSD's maximum permissible operating threshold, specifically due to high main voltage. This can be caused by unstable grid conditions, incorrect supply transformer tap settings, or other electrical disturbances. Sustained overvoltage can lead to damage to the VSD's input rectifier and DC link capacitors, potentially causing drive failure and unsafe conditions.

• Incoming mains supply voltage consistently exceeding the VSD's maximum permissible input voltage (e.g., >480VAC for a 400V rated drive).
• Grid instability or significant voltage fluctuations from the utility supply.
• Incorrect tap settings on an isolation or step-down transformer feeding the VSD.
• VSD internal DC link voltage measurement circuit failure, providing an inaccurate reading.
• Highly inductive loads or capacitor banks on the same grid segment causing voltage spikes.

Click steps to track your progress.

1. 1

   Measure the incoming mains supply voltage (L1-L2, L2-L3, L3-L1) using a calibrated voltmeter over a period of time. Record max values.

2. 2

   If an isolation transformer is used, check its tap settings. Adjust to ensure the output voltage is within the VSD's nominal input range.

3. 3

   Verify the VSD's internal DC link voltage (UDC on display). If it's abnormally high even at idle, consider a VSD internal fault.

4. 4

   Contact the utility company to investigate grid voltage stability issues if mains voltage measurements consistently exceed VSD ratings.

5. 5

   Install an appropriately sized AC line reactor on the VSD input to help mitigate voltage transients and smooth the input current.