B&W Products

SQ-300i Hybrid AVC

B&W’s SQ-300®i Hybrid automatic voltage control (AVC) is the newest addition to our proven SQ-300 product line. Based on the same trusted technology, the SQ-300i Hybrid AVC can control either a conventional, single-phase transformer rectifier (T/R) set or a low ESP voltage ripple, 3-phase T/R set.

Just like its predecessors, the SQ-300i Hybrid AVC is an integral component of the precipitator control system. It simultaneously controls power to the T/R set, analyzes alarms, and interfaces with computer-based data acquisition software. The ability to control two different types of power supplies, one which has been in use for 80 years and one that is the way of the future, adds a unique dimension to the product line.

Features of the hybrid design

The single-phase and the 3-phase power supplies originate from the same design. They both use silicon-controlled rectifiers (SCR) for power control, neither requires an active cooling system, and both exhibit high reliability. With these similarities, the development of the SQ-300i Hybrid control was a natural progression.

Benefits of the SQ-300i Hybrid AVC

  • A single-component solution for 3-phase low ripple and single-phase power supplies
  • High reliability at low cost
  • Reduced control size and complexity with modern, large-scale integration components and assemblies
  • Simplified structure; one power supply control system that can interface with plant systems
  • Decreased requirements for spare parts inventory
  • Dual-function as an upgrade component; fills immediate needs for conventional control replacements, providing continued use even if T/R sets are later upgraded to 3-phase
  • Automatic line voltage and control voltage detection
  • Switch from single-phase to 3-phase (or vice versa) with a simple firmware change

SQ-300i Hybrid Controller


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