17 Mar 06 A major project to upgrade the high voltage propulsion system, improving the electrical distribution and providing a safer system on Landing Platform Dock Ships (LPDs) Albion and Bulwark, has been designed and delivered on HMS Albion by defence support specialist the DML Group, within an eight month major capability upgrade period. This completed on 10 March, ten days ahead of schedule.
Ingress protection upgrade (from IP23, for water splash or light spray, to IP56 suitable for water leakage and high pressure jetting) was required for a number of high voltage equipment items in the main machinery spaces to avoid the need for special physical and procedural controls and to improve firefighting and damage control capabilities and operational recovery after a fire.
The need had arisen following the change from direct diesel drive to electric propulsion, resulting in 6.6kV equipment in the forward and aft engine rooms and forward auxiliary machinery room needing increased ingress protection. Because it was believed that this would require equipment to be relocated or replaced in order to house it in the requisite sealed enclosures, it was originally thought that the cost would be prohibitive.
DML designers, however (DML being platform design support co-ordinator for the amphibious assault force ships under the Design Support Alliance), challenged assumptions previously made and undertook a detailed high level hazard identification and risk analysis to assess the issue in detail. They established, working in conjunction with the OEMs (Alstom and Trasfor), that the ingress protection could in fact be upgraded in-situ for most of the equipment. An innovative route to achieve this with major cost savings was developed, providing a sound and economically viable solution.
The extensive project involved numerous challenges, given the size of some of the equipment and scale of the work package required within the tight time schedule. Some 18 major electrical propulsion components were worked on.
Much of the equipment also required a cooling system upgrade. In housing the equipment in sealed enclosures to achieve IP56 protection, air cooling was no longer applicable. DML therefore designed and developed an innovative seawater cooling system for these cases, in some instances requiring new systems, in others modification of existing systems. One transformer, weighing 20 tonnes, which could not be modified in its existing location, was repositioned to enable its cooling system to be installed, requiring sizeable access for lifting equipment to be cut in the ship’s vehicle deck.
Further, given the new complexity of the cooling system, DML also ensured that the electronic platform management service (PMS) was upgraded to ensure effective control and monitoring of the cooling systems.
A high voltage synchrodrive and switchboard could not be upgraded to IP56, so a new watertight compartment was designed and built in the forward engine room (effectively a mini-rebuild), with access via a new airlock so that the compartment could form part of the citadel of the ship.
Additionally, the new equipment and system modifications included auxiliary systems, pumps, heat exchangers and fans to harmonic filters, propulsion and ship service transformers, fresh air make up to the new mid switchboard room (MSR), and a local air conditioning unit in the lobby for air treatment in the MSR. New pipework was also required to meet the specified flow and velocity design criteria and re-balancing of the systems.
Work was also undertaken to the electrical system design to support the IP56 upgrade programme, covering all the ship systems involved, including meeting additional power supply requirements, new fire detection arrangements, and new CCTV arrangements. More than 30 electrical systems were affected. Much of the recabling work was undertaken in congested and difficult working conditions.