Vibration analysis of shaft generator driven from main engine

Abstract In recent years, offshore service vessels have increasingly used hybrid propulsion systems with generators mounted coaxially with the main engine. These latest state-of-the-art shaft generators enable ship operators and builders to benefit from efficiency, performance, and reliability. By reducing a ship’s CO2 emissions, it also helps ships meet the International Maritime Organization’s (IMO) EEDI (Energy Efficiency Design Index) measure targeting new ship designs and construction to ensure energy-efficient standards and EEXI (Existing Ship Energy Efficiency Index) measure addressing existing ships and promotes retrofits and optimizations. The paper presents the vibration analysis of Power Take Off generators (PTO) driven by engine-driven reduction gear. This analysis relates measurements of vibration carried out at 90% and 100% rated generator speed with unloaded generator and ship service speed under steady state operation. First, the study introduced experimental measurement on the same type of PTO generator installed on different ships with the same or different main engines. Second, based on this experimental measurement, the vibration analyses are evaluated and compared to relevant criteria and standards. The research results of the vibration analysis and the comparison with the criteria required on these in-shaft generators driven from the main engine were used as results of the quality assessment of the installation of hybrid propulsion systems for recent new building ships in Vietnam. This was verified by the results of vibration measurement, analysis and evaluation on shaft generators installed on three recent new-building ships.