AN ELECTRO-HYDRAULIC GOVERNING SYSTEM FOR MEDIUM RATING STEAM TURBINE SETS HAVING MECHANICAL GOVERNORS

摘要

The present invention relates to an electro-hydraulic governing system for medium rating steam turbine sets having mechanical governors, comprising a mechanical governor; and a programmable micro-processor based electro-hydraulic governor, the system is configured to generated a first sensitive oil pressure signal for a first electro-hydraulic (I/H) Converter based on output signal from the electro-hydraulic governor; generate a second sensitive oil pressure signal for a second electro-hydraulic converter from the mechanical governor; transmit under normal operating condition a positive bias signal by the electro-hydraulic governor to a load-limiting gear motor such that the second sensitive oil pressure signal generated by the mechanical governor is at a higher pressure than that of the first sensitive oil pressure signal; compare both the first and sensitive oil pressure signals in a minimum selector unit, and position the governing valves by applying the lower of said two oil pressure signals to be a governing valve relay gear.