Superior performance and versatility are demanded of generator circuit breakers. Application possibilities continue to grow.  The need for generator circuit breakers was first recognized by electric utilities to protect large generating stations, and the first editions of the industry standard were directed to this need.   However many industrial and commercial power systems now include small generators as a local source of power. New applications are arising as a result of the de-regulation of the utility industry, and the construction of smaller packaged power plants. Typical applications include:

• Electric Utility “Black Start” Generators
• Packaged Power Plants
• Combined Cycle/Combustion Turbine Plants
• Pumped-storage Facilities
• Smaller Hydro-generating Stations
• Paper, Chemical and Process Industries with on-site generation

For both large and small generator circuits consideration must be given to:

• Generator Circuit Configuration
• High Continuous Current Levels
• Unique Fault Current Conditions
• System-Source (Transformer-fed) Faults
• Generator-Source (Generator-fed) Faults
• Unique Voltage Conditions
• Very Fast Rate of Rise of Recovery Voltage (RRRV)
• Out-of-Phase Switching