External Stack Controller-598G/599G could build up to 1440A External DC Drive in one frame size. The equipment described is intended for an industrial (non-consumer) user, for the control of an external thyristor controlled bridge. The design assumes that a 2-phase field semi-controlled Rectifier Bridge and a fully controlled 3-phase Six Pulse Converter exists, which is complete with Thyristor Suppression, Current Feedback, Temperature Monitoring and suitable fusing.

The External Stack Controller Module provides:
• Thyristor Firing Signals and Pulse Transformers
• Field Power Thyristor Firing Signals and Pulse Transformers
• ACCT Feedback Rectification and Scaling
• Field CT Feedback Rectification and Scaling
• Armature Voltage Feedback Interface
• Field Voltage Feedback Interface
• Mains Present Monitoring
• Heatsink Over-temperature Input
• All Standard 590C I/O Terminations