{"id":416,"date":"2025-03-16T15:23:14","date_gmt":"2025-03-16T07:23:14","guid":{"rendered":"https:\/\/www.aswmarine.com\/?p=416"},"modified":"2025-03-19T22:32:00","modified_gmt":"2025-03-19T14:32:00","slug":"faq-from-shipowners","status":"publish","type":"post","link":"https:\/\/www.aswmarine.com\/?p=416","title":{"rendered":"FAQ FROM SHIPOWNERS"},"content":{"rendered":"

Summary of Customer Questions and Answers<\/h3>\n
    \n
  1. \n

    Does installing a shaft generator with EPL require recalculations?<\/strong><\/p>\n

      \n
    • Yes, recalculations are necessary. The engine manufacturer performs the calculations and implements necessary modifications.<\/li>\n<\/ul>\n<\/li>\n
    • \n

      What vessel types have we applied shaft generators, ducted propellers, and energy-saving fins to? What is the payback period?<\/strong><\/p>\n

        \n
      • Sales department to provide answers.<\/li>\n<\/ul>\n<\/li>\n
      • \n

        Differences in energy efficiency, cost, and time between propeller replacement and blade cutting?<\/strong><\/p>\n

          \n
        • Propeller replacement:<\/strong>\n
            \n
          • Designed based on reduced EPL speed and existing engine power.<\/li>\n
          • Lighter and better matched to the engine.<\/li>\n
          • Energy savings: 5-11% (varies per vessel).<\/li>\n
          • Cost depends on copper price; payback period is about 1.5 years.<\/li>\n
          • Design to delivery: ~3 months.<\/li>\n<\/ul>\n<\/li>\n
          • Blade cutting:<\/strong>\n
              \n
            • Modifies existing propeller geometry for better adaptation to reduced EPL speed.<\/li>\n
            • Energy savings: 1-2%.<\/li>\n
            • Completed during drydock; takes 2-4 days.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n
            • \n

              If the vessel speed suddenly drops, can the shaft generator still generate power? If the shaft stops, does the shaft generator still generate power? Where is the stored energy?<\/strong><\/p>\n

                \n
              • The shaft generator operates by using the main engine to drive a permanent magnet rotor, generating electricity through electromagnetic induction.<\/li>\n
              • It has a speed range (e.g., 50-70 rpm, 60-80 rpm) within which it produces stable power.<\/li>\n
              • If speed drops below this range for an extended period, the system will alert PMS to start auxiliary engines and disconnect the shaft generator.<\/li>\n
              • If the shaft stops, the generator ceases power generation.<\/li>\n<\/ul>\n<\/li>\n
              • \n

                Is the shaft generator a three-phase generator? A three-phase asynchronous generator? Does it output three-phase AC?<\/strong><\/p>\n

                  \n
                • It is a marine three-phase permanent magnet shaft generator<\/strong>, a synchronous generator that outputs three-phase AC.<\/li>\n<\/ul>\n<\/li>\n
                • \n

                  How do the principles of three-phase motors and frequency converters apply to the shaft generator?<\/strong><\/p>\n

                    \n
                  • Permanent magnet motor operation:<\/strong>\n
                      \n
                    • The rotor creates a rotating magnetic field, inducing AC voltage in the stator.<\/li>\n
                    • Output AC power is rectified, stabilized, and converted to a constant frequency for ship power supply.<\/li>\n<\/ul>\n<\/li>\n
                    • Variable frequency drive (VFD):<\/strong>\n
                        \n
                      • Uses two PWM converters sharing a common DC bus.<\/li>\n
                      • Motor-side converter stabilizes DC voltage.<\/li>\n
                      • Grid-side converter supplies stable AC power to the ship\u2019s electrical system.<\/li>\n
                      • Ensures stable and continuous standalone or grid-connected power generation.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n
                      • \n

                        Can the shaft generator reverse the shaft in an emergency? Where is the stored energy?<\/strong><\/p>\n

                          \n
                        • The system has PTO (Power Take-Off) mode<\/strong> for power generation and PTI (Power Take-In) mode<\/strong> for emergency propulsion.<\/li>\n
                        • In PTI mode, the ship\u2019s generators supply power, and the shaft generator acts as a motor to turn the shaft for emergency maneuvering.<\/li>\n
                        • This function requires pre-design and integration into the VFD and system.<\/li>\n<\/ul>\n<\/li>\n
                        • \n

                          Can the shaft generator and auxiliary engines supply power together?<\/strong><\/p>\n

                            \n
                          • Yes, they can operate simultaneously and are integrated with the PMS system<\/strong> for functions like synchronization, load transfer, and load sharing.<\/li>\n<\/ul>\n<\/li>\n
                          • \n

                            Do we have classification society certificates for the shaft generator, ducted propeller, and energy-saving fins?<\/strong><\/p>\n

                              \n
                            • Shaft generators have individual component certificates meeting various classification societies\u2019 requirements.<\/li>\n
                            • Ducted propellers undergo certification per ship\u2019s classification society.<\/li>\n
                            • Energy-saving fins generally do not require classification society certification but can be reviewed upon request.<\/li>\n<\/ul>\n<\/li>\n
                            • \n

                              Which countries provide warranty services?<\/strong><\/p>\n<\/li>\n<\/ol>\n

                                \n
                              • Answer provided by Mr. Hao.<\/li>\n<\/ul>\n
                                  \n
                                1. Energy-saving effects of shaft generators and high-efficiency propellers on 57,000 DWT and 170,000 DWT vessels?<\/strong><\/li>\n<\/ol>\n
                                    \n
                                  • Shaft generator savings:<\/strong>\n
                                      \n
                                    • 57,000 DWT: 0.7 tons of fuel\/day.<\/li>\n
                                    • 170,000 DWT: 2 tons of fuel\/day.<\/li>\n<\/ul>\n<\/li>\n
                                    • High-efficiency propeller savings:<\/strong>\n
                                        \n
                                      • 57,000 DWT: 7%.<\/li>\n
                                      • 170,000 DWT: 7.5%.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
                                          \n
                                        1. Differences between high-efficiency propellers and standard design propellers? Design and installation time?<\/strong><\/li>\n<\/ol>\n
                                            \n
                                          • High-efficiency propellers:<\/strong>\n
                                              \n
                                            • Custom-designed for optimal energy conversion.<\/li>\n
                                            • Uses hydrodynamic optimization to reduce losses (cavitation, turbulence).<\/li>\n
                                            • Requires balancing efficiency, strength, and manufacturing precision.<\/li>\n
                                            • Design: 4 weeks; approval: 1 month; production: 2 months.<\/li>\n<\/ul>\n<\/li>\n
                                            • Standard design propellers:<\/strong>\n
                                                \n
                                              • Based on experimental or simulated performance data.<\/li>\n
                                              • Suitable for standardized applications but lacks innovation.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
                                                  \n
                                                1. Does the shaft generator require spare parts for maintenance?<\/strong><\/li>\n<\/ol>\n
                                                    \n
                                                  • No routine spare parts are required; faulty components are repaired as needed.<\/li>\n<\/ul>\n
                                                      \n
                                                    1. Does installing a shaft generator affect main engine power?<\/strong><\/li>\n<\/ol>\n
                                                        \n
                                                      • Yes, the main engine load increases slightly. However, engines have ample power reserves, making the impact negligible.<\/li>\n
                                                      • The increase is approximately equal to the shaft generator\u2019s output power.<\/li>\n<\/ul>\n
                                                          \n
                                                        1. Why use water cooling instead of air cooling?<\/strong><\/li>\n<\/ol>\n
                                                            \n
                                                          • Air cooling:<\/strong> Lower cost, but less effective cooling, requires ventilation and space, unsuitable for retrofits.<\/li>\n
                                                          • Water cooling:<\/strong> Compact, effective cooling, can be placed in enclosed spaces (e.g., spare parts room, electrician\u2019s room).<\/li>\n
                                                          • Air cooling is available for systems below 1000 kW if cost reduction is prioritized.<\/li>\n<\/ul>\n
                                                              \n
                                                            1. How is the shaft generator’s current collected and output? Does the stator casing contain magnets?<\/strong><\/li>\n<\/ol>\n
                                                                \n
                                                              • See shaft generator operating principles.<\/li>\n<\/ul>\n
                                                                  \n
                                                                1. Can a shaft generator be removed and reinstalled on another vessel of the same tonnage if the original vessel is scrapped?<\/strong><\/li>\n<\/ol>\n
                                                                    \n
                                                                  • Yes, if the new vessel has the same tonnage, main engine speed, power requirements, and shaft diameter<\/strong>.<\/li>\n
                                                                  • The installation feasibility depends on engineering costs.<\/li>\n<\/ul>\n
                                                                      \n
                                                                    1. How does the shaft generator maintain stable power output at varying ship speeds without fluctuations?<\/strong><\/li>\n<\/ol>\n
                                                                        \n
                                                                      • The generator\u2019s voltage and frequency vary with shaft speed, requiring a VFD and rectifier-inverter system (constant voltage and frequency system)<\/strong> to stabilize the output.<\/li>\n
                                                                      • See answer to question 4.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"

                                                                        Summary of Customer […]<\/p>\n","protected":false},"author":1,"featured_media":413,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_uag_custom_page_level_css":"","site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center 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