Supervisory equipment for the indication of shaft distortion in steam turbines

The paper describes equipment which has been developed to measure the temporary distortions and disturbances which the shaft of a turbine may undergo, particularly during the starting-up period and when sudden changes of load occur during running. All measurements are made electromagnetically on a disc fitted to the shaft of the high-pressure unit, and are indicated and recorded continuously. An additional unit has been developed which indicates and records the speed of the turbine, so that shaft disturbances and speed can be correlated easily. The equipment includes a cathode-ray oscillograph which, when plugged in to the measuring circuits, produces on its screen a trace of the locus of the shaft centre, and permits investigation of abnormal disturbances of the shaft. Some of the records obtained with the equipment under operating conditions are included in the paper.