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FEATURE


ELECTRICAL & ELECTRONIC COMPONENTS As coLd As ice


Designed to make their way through even the thickest sheets of ice, icebreaker ships clear the path for vessels travelling through the coldest


regions of the earth. Specifying the right electrical components is crucial to the safe and successful operation of these in order to make even the


most treacherous of routes in the Polar regions accessible all year round. David Atkins, projects director at Cressall, comments


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round 12% of the world’s oceans are covered in ice, blocking the route for trade, research and


travel. Cutting through this ice, icebreaker ships feature a bow that is smoother and rounder than a standard vessel, allowing it to glide over thick ice sheets with minimal opposing force, with the weight of the ship descending onto the ice, crushing it and clearing the path. Commonly found in areas like the Barents


Sea, Arctic Ocean and the Saint Lawrence Seaway, ice breakers have, more recently, been used to support scientific research projects in the Arctic and Antarctic. Such vessels, however, need an electric


propulsion system designed to match the power requirements for the icebreaker’s thrusters to break through the ice. Reliability of these is essential – after all, if an icebreaker were to fail in transit, there could be major disruption to the global supply chain. One component that


plays a crucial role in ensuring the safe operation of an icebreaker’s electric propulsion system is a dynamic braking resistor (DBR).


requirements


When there is no ice in the vessel’s path, there is less load on the system, so any excess energy produced is surplus to requirements. To dissipate this, a DBR is integrated into the system which acts as a load dump during propulsion and icebreaking activities. This load dump activity stabilises the power system, giving a constant load to the vessel’s gas engines. Integrating a DBR is


absolutely essential for icebreaker vessel design engineers. Without this,


the power system would destabilise, risking potential damage to other components of the power circuit. This could eventually lead to the loss of the vessel’s icebreaking function and complete failure of the power system. However, it’s not as simple as just


selecting a DBR – there are several design elements for this specific application that must be considered to ensure the drive’s optimal performance.


component design


When designing electrical components, like resistors, for use on icebreakers, there are several application-specific factors to consider. Each component needs to be able to withstand the salty, cold and unstable conditions that are common at sea. In terms of structural stability, conducting rigorous testing procedures like finite


element analysis (FEA) provides evidence of a component’s ability to withstand unpredictable, inhospitable conditions. It’s also important to design in line with standards outlined by the global testing, inspection and certification specialists, Bureau Veritas, for global compliance. As the saline atmosphere at sea is


corrosive, selecting the right material is essential to prevent sea water from leaving equipment inoperable. For metal components, it’s important to use stainless steel with a chromium content of at least 10.5%. This enables the stainless steel to react with oxygen to produce a protective layer that prevent corrosion, even in an unpainted condition.


Cressall T: 0116 273 3633 www.cressall.com


5 DESIGN SOLUTIONS SEPTEMBER 2022 2


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