P-OFFÂ Power Off / Undervoltage Record fault in Toshiba drive
P-OFF Power Off / Undervoltage Record fault in Toshiba drive
Description P-OFF is often displayed in the fault history rather than as an active trip. It marks the moment the control power was lost. While "UP" (Undervoltage Protection) warns of low DC bus voltage, P-OFF indicates the CPU itself is shutting down due to lack of power. If P-OFF appears while the machine is supposed to be running, it indicates a total blackout or a blown internal fuse. Causes
1. Power Outage: Utility power was cut.
2. Control Fuse: The small glass fuse inside the drive protecting the control transformer has blown.
3. Loose Control Power: On larger drives where control power (R0/S0) is wired separately from mains (R/S/T), the control power wire is loose. Solution If the drive screen is blank, check the input power. If input power (480V) is present but the screen is dead, check the internal control fuses on the power board.
If P-OFF is causing nuisance stops, check the "Ride-Through" capability. You can enable "Kinetic Buffering" (Regen Ride-Through) to keep the CPU alive during brief power flickers by using the motor's spinning inertia as a generator.
Description P-OFF is often displayed in the fault history rather than as an active trip. It marks the moment the control power was lost. While "UP" (Undervoltage Protection) warns of low DC bus voltage, P-OFF indicates the CPU itself is shutting down due to lack of power. If P-OFF appears while the machine is supposed to be running, it indicates a total blackout or a blown internal fuse. Causes
1. Power Outage: Utility power was cut.
2. Control Fuse: The small glass fuse inside the drive protecting the control transformer has blown.
3. Loose Control Power: On larger drives where control power (R0/S0) is wired separately from mains (R/S/T), the control power wire is loose. Solution If the drive screen is blank, check the input power. If input power (480V) is present but the screen is dead, check the internal control fuses on the power board.
If P-OFF is causing nuisance stops, check the "Ride-Through" capability. You can enable "Kinetic Buffering" (Regen Ride-Through) to keep the CPU alive during brief power flickers by using the motor's spinning inertia as a generator.
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