What causes a PHF (input phase loss) fault on ATV61 and ATV71 drives?

A PHF fault on ATV61 and ATV71 drives indicates an input phase loss, meaning one or more supply phases are missing.

How it works:

• The drive detects a missing input phase and triggers the PHF fault.
• If one or more phases are lost while the drive is running, the drive may continue operating temporarily and then stop due to another fault (such as USF – undervoltage fault).
• In some cases (e.g., when the motor is acting as a generator), the fault may not be detected immediately.
• The PHF fault condition is stored in memory (EEPROM) during operation.

Important notes:

• The IPL (Input Phase Loss) parameter can be set to NO to disable phase loss detection when using DC bus supply (typically for 230 V or 480 V ranges).
• Some smaller drives (230 V models up to 7.5 kW) may have IPL = NO by default, as they are designed to run on single-phase input.

Common causes:

• Loss of one input phase
• Blown or open fuse
• Incorrect power supply wiring
• Using a single-phase supply on a drive configured for three-phase input

Recommended solutions:

• Verify all power connections are secure
• Check and replace any blown fuses
• Ensure the drive is supplied by a proper three-phase network
• If appropriate for the application, disable the input phase loss detection (IPL = NO)

If this article does not answer your question, check out our FAQ database that has answers to more commonly asked questions:

Frequently Asked Questions - Schneider Electric (se.com)

If this FAQ did not solve your issue, you can call us at 1-888-778-2733 Option 2 and then 4 or e-mail us atdrive.products.support@se.comto create a case with our Technical Support Team.

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