AL555 alarm in delta servo drive indicates System failure. This means a serious issue that has prevented the drive from operating correctly. This could be due to various reasons, including hardware failures, software glitches, or incorrect parameter settings.

1. Check the power supply voltage and current to ensure they are within the specified range.
2. Inspect the drive's internal components for any signs of damage, such as burnt resistors or capacitors.
3. Update the drive's firmware to the latest version to address known bugs and improve performance.
4. Ensure the power supply is providing the correct voltage and current.