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Ship in shore: HMS Vengeance in dry dock at Devonport for the overhaul
Trials are set to begin on a new electrical power conversion system that forms part of life-extension work on the Vanguard class of nuclear-powered ballistic-missile submarines.
The main static converters (MSCs) replace the traditional 650kW motor generators, an essential part of the submarine’s onboard electrical power system. The MSCs provide a fixed, solid-state power electronics alternative that avoids the need for rotating machinery. This promises advantages over motor generators, being significantly more reliable and with considerably reduced through-life maintenance requirements, said the Royal Navy.
Commander Ian Bartlett from the Ministry of Defence said: “The 650kW motor generator sets replaced by the main static converters have a high maintenance requirement and have historically injected significant tension during submarine maintenance periods. Their removal improves the delivery of continuous at-sea deterrence.”
Installation and initial power-up of the main static converters have been completed on HMS Vengeance during the Long Overhaul Period and Refuel project being undertaken by Babcock at Devonport dockyard in Plymouth.
As part of the programme, electrical, constructive and mechanical integration challenges have been addressed. Babcock undertook detailed assessments of the auxiliary machinery spaces on all Vanguard submarines using a laser scanning technique which enabled a detailed 3D CAD model to be created for the mechanical and constructive designs. Among the challenges was the need for the main static converters solution to meet the high power demands of ballistic nuclear submarines, while being smaller than the Astute-class version to fit within the available compartment space.
Size and available space have been key issues from the point of view of positioning and installation within the compartment and shipping routes into the submarine. Other considerations in finalising the design have included electrical integration, and integration into the current control systems, as well as determining the best method to shock mount the new suites, and minimising changes to the cooling water system.
Installation involved removal and clearance of the original motor generators and their seatings, welding in new seatings and structure to accept the main static converters and fitting of bed plates. The individual units were lifted onboard and through the submarine to their final location to avoid any damage. A team of fitters then connected the main static converters to the electrical and cooling systems, and tested each in turn. The installation phase has taken 18,000 manhours, and commissioning will take 10,000 manhours.
The next phase is to commission the systems when the ship’s diesel generators are working, after which they will be operated and tested during steam machinery trials, when they will work alongside the ship’s turbo generators.
Final commissioning of the MSCs will take place in 18 months’ time during preparation for sea trials.