It’s a harsh world… part 10 – Drives vs. Nature

Wednesday, August 24, 2016
AC Drive placed outside by a pond covered by a SunShield

If you’re anything like me, during the summer months, you spend as much time as possible outdoors and in nature. Whether it’s hiking, biking, swimming, camping, or just laying out on the beach, the same conditions we subject our bodies to can be the same conditions that your AC drives could potentially be exposed to.

Sure, it’s true that most of the time, your AC drives are mounted indoors, inside an enclosure in a nice (hopefully) clean, climate-controlled room. But plenty of AC drives are serving applications in locations that aren’t so safely contained indoors. It’s these drives that we’re focusing on here today.

From solar pumping to rooftop applications to farms and many other locations, AC drives are mounted directly outside where they can be exposed to many varieties of natural occurrences. Heat, cold, rain, snow, ice, wind, vibrations and, probably most importantly, UV exposure are all potential situations that your AC drive may encounter. Since we’ve taken a look at several of these topics individually, let’s just review, quickly, what we’ve learned.

Classifying drives for outdoor use

In Drives vs. Enclosure classifications, we learned what it takes for an AC drive to be classified for outdoor use. We saw that the Ingress Protection classifications (IP classifications) don’t specifically account for outdoor use. While the UL Type classifications common to North America minimally utilize the UL Type 3R classification rating for outdoor use, taking into consideration common precipitation events. Both systems typically require further specification to high environmental classification ratings such as IP66 or UL Type 4X to be rated for outdoor use. Just because a product is rated IP66 or UL Type 4X does not necessarily mean that it is suitable for outdoor use. If it’s not clearly stated, contact your AC drive supplier for confirmation. The last thing you want is for your AC drive to fail due to the weather and not being covered by a warranty because it was improperly protected from the elements!

Getting the temperature right

Then, in Drives vs. Low temperatures, we learned that, while it’s important to keep your AC drive cool, there’s such a thing as ‘too cool’. When you expect to encounter regular ambient temperatures below -10°C/+14°F during operation, it’s important to know that derating may be required for continuing operation. Additionally, storage temperatures below -25°C/-13°F can cause issues with your AC drives. In either case, ensuring a stable temperature throughout the operation by supplying a means of heating your AC drive is probably the most important step you can take to protect it in these environments. Additionally, preventing ice formation and regular freezing/melting cycles will reduce the possibility of your AC drive’s components being damaged by moisture.

Next, in Drives vs. High temperatures, we learned that keeping your AC drive temperatures carefully regulated is the number one step you can take to ensure that it is always operating at peak capacity and supplying the power you expect for your applications. Creative mounting strategies, such as utilizing back channel cooling solutions or flange mounting help to isolate the heat-producing elements and reduce the active cooling needs. Additionally, liquid-cooled solutions are great alternatives where high ambient temperatures are more often encountered or when space is at a premium.

Lastly, in Drives vs. Condensation, humidity and corrosion, we looked at the impact of moisture on your AC drives. We learned that higher levels of relative humidity increase the likelihood of condensation, especially in areas where salt mists (ocean areas), for example, are encountered. Furthermore, a wide difference between the surface temperature of an object (like the heat sink of an AC drive) and the air around increases the possibility of condensation forming. This condensation, when further mixed with other corrosives, especially at higher temperatures, results in extremely quick corrosion which leads to premature equipment failure.

So if we’ve already learned so much about these topics, why the special post for mounting in outdoor conditions? Well, that’s easy. We reach some unique situations when your AC drive is mounted out there in nature.

Protecting drives from the elements

The first unique situation has to do with heating and cooling an AC drive when it’s not mounted in a central location. As you can imagine, it’s not exactly easy to apply a heater or air conditioning unit to an AC drive mounted in the elements. At least when it comes to heating, though, there are certain solutions that work quite well. For example, the Arctic Mode Heater option for the VACON® 100 X supplies you with an independently powered internal heater that is mounted as part of the drive itself while allowing it to maintain the IP66 / UL Type 4X outdoor rating.

The second, while in a way connected to the challenges of cooling an AC drive that’s mounted outside, is the sun itself. As we all have experienced before, standing directly in sunlight results in you becoming warmer. And we all know how it feels to get in a car that’s been sitting in direct sunlight for far too long. AC drives also experience the effect of exposure to sunlight but, due to a limited ability to cool themselves off, become even more susceptible to operational issues.

But the sun not only contributes heat to the AC drive. It also contributes ultraviolet (UV) radiation mixed in with the visible light. UV radiation reacts with all types of materials in different, and quite often destructive, ways. Leave fabrics out in the sun and the colors will, after some time, start to fade. Colors in many plastics will also fade over time. But, most destructively for AC drives, the enclosures, if not properly designed with materials that resist breakdown due to UV radiation, will not only discolor but start to crack and become brittle. This reduces any ability that the enclosure of the AC drive would otherwise have been rated for. As the enclosure degrades, it loses its ability to keep out water and dust. But the enclosure is not the only element suffering the effects of UV radiation. Other elements, such as the display or the cable glands, can be affected if they are not ‘UV-proof’.

Luckily, there are some strategies that can be used to minimize the impact of the sun on your AC drive. If your AC drives can’t be mounted in a location without direct exposure to sunlight, the first option is to add a form of sun shield that prevents the sunlight from shining directly on it. This protects the drives from the UV effects and, at the same time, reduces overheating which is particularly important in hot climates. Make sure, however, that the shield is mounted in a way that it won’t obstruct the airflow over the cooling fins.

If this first option is not feasible, you should at least select an AC drive for your application that is rated for outdoor applications. One that is made with special enclosure and gasket materials that resist UV damage as well as being tested for special types of corrosion found only in outdoor applications.

As you can see, the outdoors provides some unique challenges to your AC drive installations. Making smart, informed, choices during selection and installation will help to ensure that your AC drives will continue to operate as efficiently as possible for as long as possible.

Check back regularly with us here at for frequent updates on the best ways to ensure that your investments in AC drives are always the safest investments around. Next time, in Part 11 in the “It’s a harsh world…” series, we’ll discuss Drives vs. Explosive environments where we take a closer look at how to make sure your AC drive doesn’t put your application at risk by taking proper precautions in these challenging environments. Additionally, let us know in the comments what environmental impacts give you the biggest challenges and how we can help you overcome them. Regardless of whose name is on the label, we’re here to help! In the meantime, you can find out more about all our products here.

Jake Roeder, Global Product Marketing Manager, Danfoss Drives
Abraham González Ponce, Application Knowledge Manager, Application & Service Products, Danfoss Drives