Accelerator backup and NetBackup catalog
Accelerator does not affect the size of the NetBackup catalog. A full backup with accelerator generates the same catalog size as a full backup of the same data without accelerator.
The same is true of incremental backups; accelerator does not require more catalog space than the same backup without accelerator. A potential catalog effect does not occur, depending on how often you use accelerator with full backups.
A full backup with accelerator completes faster than a normal full backup. It may therefore look advantageous to replace your incremental backups with accelerator full backups.
Since a full backup requires more catalog space than an incremental one, replacing incremental backups with full backups increases the catalog size.