Marelli Motori has recently designed and built new alternators for one of the main players in the marine business, energy sector. Our customer had requested our R&D engineers to develop alternators that, combined with their diesel engines and mounted on a standard skid, were able to meet specific requirements in terms of sustainable vibrations according to the ISO 8528 - Level 2 standard.
The ISO 8528 describes a procedure for measuring and evaluating the external mechanical vibration behaviour of generating sets at the measuring points. This standard applies to a.c. generating sets driven by Reciprocating Internal Combustion (RIC) for fixed and mobile installations with rigid and/or resilient mountings.
Following an important effort in Research & Development, paired with 128 years of experience in building electrical rotating machines, we have very successfully optimized our MJRM marine generator series achieving a new design able to comply with all the stress and fatigue parameters required for marine alternators. The new design allows to avoid any mode-shapes of the alternator which could combine with the harmonic forcing from the engine.
During this technical development, we have focused on any possible static and dynamic structural aspect involved. Static and rotating elements have been optimized through numerical simulations to guarantee the mechanical reliability and thermal efficiency of our alternators.