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Home > Trends & Technology > An Ounce of Prevention: Thermal Cooling for Electrical Installations
Thursday, January 11, 2018
POSTED BY TURTLE & HUGHES INDUSTRIAL CONTROL & AUTOMATION DEPARTMENT BLOG IN
PERSPECTIVES, PRODUCTS & TECHNOLOGY
In electronic installations, companies often put a lot of time and effort into choosing the right components, but protecting those components is often an afterthought. What many don’t realize is that failure to safeguard sophisticated and sensitive electronics, especially from high temperatures, can be an extremely costly mistake. The right electrical enclosure with the proper cooling system will preserve expensive equipment and keep employees safe.
The cooling system is the key to preventing electronic component failures that could lead to a shutdown of the entire production system – and hit a company’s bottom line hard.
The need for adequate cooling systems has grown in recent years and is predicted to increase over time. Microelectronics and other new technologies are increasing the heat inside industrial enclosures, making temperature control more important than ever.
Research has shown that for every rise of 18 degrees Fahrenheit above the normal room temperature of 72–75 degrees Fahrenheit, the reliability of electronic components is cut in half. At high temperatures, drive performance is de-rated, I/C-based devices are adversely affected by erratic output and voltage migration, and the properties of silicone materials change. Wiring insulation is also negatively impacted while the temperature is high — elasticity and strength are reduced, and ductility and atomic mobility increase.
Cooling isn’t simply a matter of reducing the temperature — cool things down too far and the enclosure’s surfaces can pass below the dew point, leading to condensation that can speed corrosion and battery failure, and cause I/C-based devices to behave strangely. Cooling systems need to keep electrical components at a temperature that’s just right.
Internal condensation from localized temperature differences poses a significant risk. Such condensation occurs when moist air comes into contact with a cool surface. Outside air, rain and wash water can all enter enclosures if they’re not kept sealed, with only minimal door opening for service and maintenance. Creating a set point for the temperature inside the enclosure will avoid condensation issues.
The right set point for temperature will:
Condensation in the enclosure doesn’t just affect the components, it can also cause short circuits that may lead to arcing or sparking, putting employees in danger.
So how do you choose the right temperature? Each enclosure is different, but the challenges are the same for all of them.
The desired temperature is set via controller, but this controller might have what is known as hysteresis, which simply means a lag in the change of state of a system. So the unit could be set to a particular temperature point, but the enclosure might actually be operating at a different temperature than the set point depending on fluctuations in the heat from the components. The temperature within the cabinet might also vary at different corners. The best practice is to take care of variation inside the cabinet and the hysteresis of the controller by setting the temperature to a lower point.
For NEMA 12 cabinets, for example, the maximum temperature before wiring insulation performance starts to degrade for a Class A wire is 104 degrees Fahrenheit. Adjusting the set point to 80 degrees Fahrenheit for these enclosures should ensure that both hysteresis and temperature fluctuations can be handled without components reaching 104 degrees Fahrenheit. Because enclosures run hot, the variations can generally be relied upon to be hotter than the desired temperature rather than lower. At a low set point, variations can be accounted for and still keep the cabinet below 104 degrees Fahrenheit.
If proper enclosures and cooling solutions are ignored, expensive well-chosen equipment can quickly fail, at significant cost. The most cost-effective approach is to not consider an installation complete until the components are protected and adequately cooled.
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