| 307 /  |   HD   |    ELECTRICAL TRANSMISSION OR INTERCONNECTION SYSTEMS | 
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| 43 |   | PLURAL SUPPLY CIRCUITS OR SOURCES {14} | 
| 44 |   DF   | .~> One source floats across or compensates for other source {3} | 
| 51 |   DF   | .~> Circulating- or inter-current control or prevention | 
| 52 |   DF   | .~> Load current control {4} | 
| 64 |   DF   | .~> Substitute or emergency source {3} | 
| 69 |   DF   | .~> Sources distributed along load circuit | 
| 70 |   DF   | .~> Load transfer without paralleling sources | 
| 71 |   DF   | .~> Series-parallel connection of sources | 
| 72 |   DF   | .~> Diverse or unlike electrical characteristics {3} | 
| 77 |   DF   | .~> Series-connected sources {1} | 
| 80 |   DF   | .~> Selective or optional sources {1} | 
| 82 |   DF   | .~> Plural converters | 
| 83 |   DF   | .~> Plural transformers | 
| 84 |   DF   | .~> Plural generators | 
| 85 |   DF   | .~> Connecting or disconnecting {1} |