Mains Overvoltage

What does OSF mean?

An oversupply (mains overvoltage) detected fault. This means the incoming AC supply voltage to the drive has exceeded its safe operating limits. This condition can damage the drive's input stage components and internal DC bus capacitors if not promptly addressed.

• Incoming AC mains supply voltage exceeding the drive's maximum input voltage rating (e.g., > 480V for a 400V drive).
• Regenerative energy from an overhauling load causing the DC bus voltage to rise beyond its trip limit (often combined with no braking resistor).
• Voltage spikes or transients on the mains supply line (e.g., due to capacitor switching, lightning strikes, or large load changes).
• Incorrectly configured drive for the supply voltage (e.g., 230V drive inadvertently connected to 400V mains).
• Faulty voltage sensing circuit within the drive's input stage, leading to an inaccurate overvoltage detection.

Click steps to track your progress.

1. 1

   Measure the incoming AC line voltage (L1-L2, L2-L3, L3-L1) at the drive's input terminals using a true RMS voltmeter.

2. 2

   Compare the measured voltage to the drive's specified input voltage range (e.g., 380-480VAC) as indicated on its nameplate.

3. 3

   If a braking resistor is installed, verify its resistance and connection to the drive (e.g., R+, R- terminals) and check for proper operation.

4. 4

   Increase the deceleration time (e.g., Parameter P2-02) if the fault occurs during motor stopping, to reduce the rate of regenerative energy return.

5. 5

   Install an input line reactor (choke) or an active front end (AFE) if the mains voltage is unstable or prone to frequent transients.