A manual/automatic synchronization circuit for a 37.5 MVA steam turbine driven generator

A manual/automatic synchronization circuit has been designed for a 37.5 MVA generator with protection for all three critical synchronizing parameters. The circuit uses triply redundant protective levels for both the manual and automatic circuits. The first and second protective levels, consisting of a solid-state automatic synchronizing relay in tandem with a solid-state synchronization check relay, are shared by both circuits. An operator/synchroscope provides the third protective level for the manual circuit, and a microprocessor-based governor provides the third protective level for the automatic circuit. The author reviews the philosophy, design, and operation of this manual/automatic synchronization circuit