The New England Electric System Tests Effectiveness of Stop-Valve Bypass in Reducing Thermal-Stress Gradients in Steam Turbines

The stop-valve bypass valve enabling full-arc admission starting is now being utilized extensively as a means of reducing transient thermal-stress gradients in steam turbines. This paper describes, with the aid of start-up test graphs, the results of an intensive series of tests conducted by the New England Electric System, which was designed to determine the effectiveness of this bypass valve. One of the machines tested was equipped with an electrical long-range speed governor which was used to bring the turbine to speed in a predetermined and accurately controlled way. This installation represents the first successful application of this device on a General Electric Company steam turbine-generator. A brief description is included.