Ramp Differential Expansion Measurements with the SKF Multilog On-line Protection System DMx

As described in the differential expansion application note, publication number CM3073 EN, the SKF Multilog On-line System DMx is specifically designed to perform critical measurements which are used in the control of large steam turbine generator trains. One of the most important measurements is that of differential expansion.

Differential expansion monitoring measures the change in axial clearances between the machine rotor and stationary casing caused by thermal changes inherent in most machines. The primary purpose of a differential expansion monitor is to guard against axial rub between rotating and stationary parts, the consequences of which can be catastrophic.

There are many configurations for measuring differential expansion.This application note discusses the common sensor configuration of ramp differential expansion (abbreviated to “RDE”). The sensor orientation is considered, together with the appropriate SKF Multilog DMx configuration example.