Code F021: Output Ph Loss
Issue Description & Safety Warning
The Allen-Bradley PowerFlex 520 Drive has triggered a critical Output Ph Loss alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
Type: 1 Output Phase Loss (if enabled). Configure with A557 [Out Phas Loss En]. • Verify motor wiring. • Verify motor.
Source: Allen-Bradley PowerFlex 520-Series AC Drive User Manual (520-UM001)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Allen-Bradley PowerFlex 520 Drive Alarms
Allen-Bradley controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code F021 on the PowerFlex 520 Drive identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Allen-Bradley's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 45 Allen-Bradley PowerFlex 520 Drive codes.
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