Low-voltage linear DC drive selected for sub-sea scanner

Sonomatic manufactures specialised non-destructive scanners such as the Nautilus model, a diver-deployed automated ultrasonic system that can operate in depths of up to 250m. The Nautilus scanner is designed to adapt to an in-situ mineral or gas pipe junction, or an existing pipe, to monitor the quality of a new weld or the condition of an existing pipe. These can be on land, shipboard or sub-sea. The sub-sea applications present the most demanding technical conditions.

Furthermore, Sonomatic has developed technology to overcome the difficult task of adding a new pipe junction (hot tap) to oil and gas pipelines on the sea bed. A habitat is constructed around the hot tap site, approximately the size of a transportation container, which is then filled with a mixture of helium and oxygen to enable the divers to enter and work in a dry environment. The divers can work up to 150m under water, so providing these habitats is a major achievement itself.

With the Nautilus scanner fitted to the hot tap, Sonomatic technicians carry out inspections and analyses using Sonomatic's Microplus Digital Imaging System. Data is sent from the Nautilus scanner to the technicians through a 250m long umbilical cable. The data provides accurate mapping and analysis of the condition of the new pipe junction's weld.

Sonomatic chose the Sprint Electric 200XLV linear drive to provide the low-voltage DC control for the Nautilus' axis motors. Typically one motor drives the circumferential axis to track around the pipe; the other drives the axial axis that moves the scanner head in and out while rotating around the pipe.

Less filtering required

The 200XLV was chosen because of its low-noise signature. The low-level electrical signals produced by the scanner make them very susceptible to electrical interference, especially when the signal cables are alongside power cables in the umbilical cable bundle. The 200XLV reduces the need for heavy filtering of the drive and motor cables over conventional PWM devices.

Sprint Electric's 200XLV is a miniature, fast-response DC motor speed controller typically used for driving brushed DC motors, gear-motors, low-inductance printed motors and linear actuators rated up to 100W. It is suitable for low-power applications such as robotic control and antenna or security camera drives that rely on an unregulated DC or battery supply up to 48V. Offering high bandwidth and a superbly linear, noise-free output, the 200XLV is useful for the control of linear actuators. Despite measuring just 40mm wide, 82mm high and 50mm deep, the 200XLV is a genuine four-quadrant drive that can motor and brake in both directions of rotation to offer outstanding control of motor speed and torque.

For more information about the 200XLV, go to www.sprint-electric.com/products/200xlv.