MRO Magazine

Drive Upgrade Propels Development

VT Shipbuilding in Portsmouth, England, designs and constructs naval vessels for the Royal Navy and navies worldwide, as well as smaller craft and equipment for the marine, offshore and aerospace indu...


November 1, 2008
By MRO Magazine

VT Shipbuilding in Portsmouth, England, designs and constructs naval vessels for the Royal Navy and navies worldwide, as well as smaller craft and equipment for the marine, offshore and aerospace industries. During a recent major refurbishment program at its propeller testing facility in nearby Portchester, a cavitation tunnel control system was retrofitted with new DC drives.

VT Shipbuilding has state-of-the-art facilities in Portsmouth. Naval vessels built by VT range from advanced surface warships — including frigates, corvettes, fast-attack craft and mine countermeasure solutions — to offshore patrol vessels and patrol craft.

Cavitation is the process where a void or bubble in a liquid rapidly collapses, producing a shock wave. Cavitation often occurs with propellers and can cause undesired noise, damage to components, vibration and a loss of efficiency.

Propeller tests and the study of the forces on rudders, fins, submerged bodies, hydrofoils and cable fairings are carried out in a cavitation tunnel. VT’s cavitation tunnel, first commissioned in 1956, has since then been involved in extensive performance assessments of propellers for both in-house and consultancy work.

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A new drive system was installed during the cavitation tunnel refurbishment. Design, build and installation of the new control system was completed by Hemco Power and Control Systems Ltd. of Eastleigh, Hampshire. The specialists for electrical control systems used two four-quadrant DC drives from Sprint Electric to replace an aging Ward Leonard control system that dated back to the 1970s.

Using the original motors, one DC drive, a PLX65/155Amp, now controls the tunnel drive system, which operates a four-bladed impeller to achieve water velocities up to 8 m/s. A second drive, a PLX40/99Amp, operates a Kempf and Remmers propeller dynamometer, which allows a test propeller to rotate up to 1,800 rpm while acquiring torque and thrust measurements.

Integrated with new control and data acquisition software, the new PLX DC drives allow for automated control of tests and experiments, bringing with them time savings as well as improved test accuracy and quality. These benefits, plus lower energy consumption, make the DC drives ideal for retrofits when a more effective, modern drive system is required.

For more information on VT Shipbuilding, visit www.vtplc.com.Sprint Electric drives are distributed in Canada by MDA Controls Inc., Oakville, ON.

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