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Why cooling matters

The thermal engineering team provides technical expertise and innovative tools for improving the thermal performance of our electrical machines.

We work with global design teams to support new product introductions, current products as well as our customer engineering team. The main challenge we face, is to do our job without negatively affecting the machine's electrical or mechanical performance. In doing so, we come up against a number of limiting factors; such as temperature class limits (NEMA & IEC) and efficiency targets.

To give an idea; a 10∞C rise over the standard temperature will halve the machine's life and reduce the machine's efficiency by 2%.

So, what is 'thermal performance'' It refers to the machine's self-cooling capability and the temperatures it reaches as a result. Cooling is achieved by a fan that is driven by the alternator shaft which induces an airflow through the machine. This airflow then splits between the rotor†and stator.

Airflow and temperature are directly related; as the former goes up, the latter drops. So the bulk of our work focuses on designing innovative ways of optimising this airflow. The simplest way of doing this is to increase the overall airflow. We have designed the new, more aerodynamic drive-end adapter, which has given us upto 10% increase through CoreCooling' technology. This resulted in a 12∞C drop in machine temperature.

Another way of optimising the airflow is to re-distribute it to hotter areas of the machine. We've worked cross-functionally to add extra cooling channels at the centre of the machine. This introduces cooling air at the machine's hotspot, giving maximum benefit.

In order to validate these technologies, we use the test facilities at our Stamford plant along with thermal modelling tools like Computational Fluid Dynamics (CFD).

As cost, power density and efficiency requirements become more stringent, the thermal engineering function plays an increasingly important role in ensuring we give our customers the best possible product.

Joseph Borg and Darren Camilleri