A "bb" alarm in a Yaskawa drive signifies a Base Block condition. This indicates that the output power to the motor has been intentionally blocked. It's not necessarily a fault, but rather a state where the drive isn't supplying power.

Here's a breakdown of the "bb" alarm and how to address it:

Cause:

Several factors can trigger a "bb" alarm:

• External Baseblock Signal: An external control system might be deliberately stopping the drive through a designated input terminal.
• Missing Minimum Input: The drive might require a specific minimum input signal (like voltage) to enable operation, and it's currently not being met.
• Drive Configuration: Certain Yaskawa drive parameters might be set to prevent operation until specific conditions are satisfied.

Troubleshooting Steps:

1. Consult the Manual: The first step is to refer to the Yaskawa manual for your specific drive model. It will provide detailed information on the "bb" alarm and its potential causes.
2. Review Control System Logic: If you're using an external control system, verify that it's not intentionally sending a base block signal to the drive.
3. Check Input Signals: Ensure that any required minimum input signals are present and within the expected range.
4. Drive Parameters: Review the Yaskawa drive parameters to confirm they're set correctly and not preventing operation due to specific conditions.