Allen-Bradley · PowerFlex 520-series Adjustable Frequency
The output torque current has fallen below a programmed minimum level (A490 [Load Loss Level]) for a duration longer than the set time (A491 [Load Loss Time]). This indicates that the mechanical load on the motor has been lost or significantly reduced, possibly due to a broken belt, coupling failure, or pump cavitation.
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Physically inspect the mechanical coupling between the motor and the load (e.g., belts, gears, shafts) for damage, looseness, or disconnection.
Observe the actual motor current (P0-04 [Motor Current]) during normal operation and compare it to the parameter A490 (Load Loss Level). Adjust A490 to be below the typical minimum operational current.
Verify the integrity of the process material flow (e.g., liquid level in a tank, material on a conveyor belt) impacting the mechanical load.
Check for any damage or obstruction in the driven equipment (e.g., pump impeller, fan blades, conveyor rollers) that would reduce the load.
Confirm that A491 (Load Loss Time) is set appropriately for the application, allowing for normal brief load fluctuations without tripping.