Telemetry Systems for Measurements in Rotating Machines

Abstract

Telemetry systems provide a versatile means of measuring parameters like vibration, strain or temperature of rotating machines such as turbines, fans and compressors. Vibration monitoring of turbine and fan blades plays a major role in evaluating the blade performance and also in designing and developing new blade profiles. Telemetry systems can also be used for continuous monitoring of vibration and stress of the blades during regular operation so that any likely failure of the blades can be predicted in advance. Apart from constraints of dimension and weight, measurement systems (transmitting side) for such applications have to meet the high centrifugal forces while in rotation. After briefly touching upon such factors, the paper describes the various schemes available and the one used. The paper goes on to describe the details of a commercially available single channel telemetry system and an indigenously developed multi-channel telemetry system for such applications. As an illustrative case, the application of the commercial telemetry system for the measurement of dynamic strain in the PA fan impeller is described.