7584 LSU Charge Failed Fault in ABB ACS880 Drive

7584 LSU Charge Failed in the ABB ACS880 Drive indicates that the Line Supply Unit (LSU) was not ready within the expected charging time. During startup, the inverter waits for the supply unit to complete its precharge sequence and become ready for operation. If the main contactor or circuit breaker cannot close or the supply unit fails to reach the ready state within the specified time, the drive generates Fault 7584.

This fault generally indicates a problem with the Line Supply Unit (LSU), communication between the inverter and supply unit, control permissions, or the main contactor/breaker, rather than a fault with the motor itself.

Possible Causes

  • Line Supply Unit (LSU) failed to complete the charging sequence.
  • Main contactor or circuit breaker failed to close.
  • Communication between the inverter and the supply unit is disabled.
  • Parameter 95.20 – HW Options Word 1 is incorrectly configured.
  • Supply unit communication hardware is faulty.
  • Supply unit is not enabled.
  • Supply unit is not permitted to start.
  • Supply unit is operating in Local Control mode instead of Remote Control mode.
  • External interlock preventing supply unit startup.
  • Loose or damaged communication wiring between the inverter and LSU.
  • Faulty main contactor coil.
  • Defective circuit breaker control circuit.
  • Auxiliary contact feedback failure.
  • Power supply to the LSU is unavailable.
  • Internal supply unit hardware failure.
  • Control board communication failure.

Solutions

  • Cycle power to the drive and check whether the fault clears.
  • Verify Parameter 95.20 – HW Options Word 1 is correctly configured to enable communication with the supply unit.
  • Check that communication between the inverter and LSU is active.
  • Verify the supply unit is enabled.
  • Confirm the supply unit is allowed to start.
  • Ensure the supply unit is operating in Remote Control mode if it is intended to be controlled by the inverter.
  • Inspect the main contactor or circuit breaker for proper operation.
  • Verify the contactor coil energizes correctly.
  • Check auxiliary contact feedback signals.
  • Inspect communication wiring between the inverter and supply unit.
  • Verify all communication connectors are securely connected.
  • Inspect external interlocks that may prevent startup.
  • Check the supply voltage to the LSU.
  • Replace defective contactors, breakers, or communication hardware if necessary.
  • Contact ABB technical support if the fault persists after inspection.

Additional Information

The ABB ACS880 drive system may include a separate Line Supply Unit (LSU) that manages the incoming power supply and performs the DC bus charging (precharge) sequence before normal operation begins.

When a start command is issued, the inverter waits for the LSU to:

  • Complete the precharge sequence.
  • Close the main contactor or breaker.
  • Indicate a Ready status.

If the LSU does not become ready within the expected time, the inverter generates Fault 7584.

One of the most common causes is incorrect configuration of Parameter 95.20 – HW Options Word 1, which enables communication with optional hardware such as the supply unit.

The fault may also occur if the supply unit:

  • Is operating in Local Control mode.
  • Is disabled.
  • Is prevented from starting by external interlocks.
  • Cannot be controlled by the inverter.

Unlike a communication fault, Fault 7584 specifically indicates that the LSU failed to complete its startup and charging sequence within the allowed time.

Common Symptoms

  • Drive trips with Fault 7584.
  • Inverter will not start.
  • Main contactor does not close.
  • Supply unit remains in a non-ready state.
  • DC bus charging sequence does not complete.
  • Fault appears immediately after a start command.
  • Supply unit remains in Local Control mode.
  • Communication with the supply unit appears inactive.
  • Fault remains after reset.
  • Drive cannot energize the motor.

Recommended Troubleshooting Sequence

  1. Cycle power to the drive.
  2. Verify Parameter 95.20 – HW Options Word 1.
  3. Confirm communication between the inverter and LSU is enabled.
  4. Verify the supply unit is enabled.
  5. Ensure the supply unit is permitted to start.
  6. Confirm the supply unit is in Remote Control mode.
  7. Inspect the main contactor or circuit breaker.
  8. Verify the contactor coil operates correctly.
  9. Check auxiliary contact feedback.
  10. Inspect communication wiring and connectors.
  11. Verify external interlocks are not preventing startup.
  12. Check the incoming power supply to the LSU.
  13. Replace defective contactors, breakers, or communication hardware if required.
  14. Verify successful completion of the charging sequence.
  15. Contact ABB technical support if the fault persists.

LSU Charge Check Table

Check PointAction
Power cycleRestart the drive
Parameter 95.20Verify HW Options Word 1 configuration
LSU communicationConfirm communication is enabled
Supply unitVerify it is enabled
Supply unit control modeEnsure Remote Control mode is selected
Start permissionVerify LSU is allowed to start
Main contactorCheck proper operation
Circuit breakerInspect closing operation
Contactor coilVerify correct energization
Auxiliary contactsCheck feedback signals
Communication wiringInspect between inverter and LSU
External interlocksVerify no startup inhibition
Incoming supplyCheck power to the LSU
ABB technical supportContact if the fault remains after inspection

Preventive Maintenance Tips

  • Periodically inspect the main contactor and circuit breaker for reliable operation.
  • Verify Parameter 95.20 – HW Options Word 1 after commissioning or hardware replacement.
  • Ensure the LSU remains configured for Remote Control mode when controlled by the inverter.
  • Inspect communication cables and connectors between the inverter and supply unit during scheduled maintenance.
  • Test auxiliary contact feedback circuits regularly.
  • Verify external interlocks operate correctly and do not unintentionally inhibit startup.
  • Keep control cabinets clean and free from dust and moisture.
  • Inspect contactor coils and switching mechanisms for signs of wear.
  • Use only ABB-approved replacement components for the LSU and associated hardware.
  • Record recurring LSU charging faults to assist long-term diagnostics.

Proper verification of Parameter 95.20 – HW Options Word 1, confirmation that the Line Supply Unit is enabled, in Remote Control mode, and permitted to start, along with routine inspection of the main contactor, circuit breaker, communication wiring, and external interlocks, will help prevent recurring 7584 LSU Charge Failed faults in ABB ACS880 drives, ensuring reliable DC bus charging, dependable startup, and long-term operation of the drive system.

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