Multi-planes Rotor Unbalance Estimation using Influence Coefficient Method

The rotor mass unbalance is probably the most common rotor fault in any rotating machine. If the rotor mass unbalance exceeds the allowable limit, it will cause an excessive vibration which may lead to machine failure. Therefore, the regular in-situ rotor balancing is often required to keep machine vibration within acceptable level. Current practice in industries is to use a single machine speed for balancing the rotor by the Influence Coefficient (IC) method. This paper investigates the effect on the unbalance estimation by the application of the IC method using measured machine vibrations at a single speed as well as multiple speeds simultaneously during machine transient (run-up or run-down) operation. This study is carried out on an experimental rotating rig with two balancing planes. The current paper presents the laboratory rig, unbalance experiments carried out and the sensitivity analysis of the unbalance estimation using measured machine response at speed ranging from a single speed to multiple speeds.