## Calculate Heat Loads from the Sun for Outdoor Control Panels

I am always happy to see the sun rise each morning. But, electrical panels that are exposed to the sun are not.  Solar heat adds significant BTU’s to the overall heat load in an electrical panel.

A customer had a VFD to control a 300HP blower motor for a dust collection system. The VFD was getting an over-temp error and shutting down the system.  He contacted EXAIR to get a Cabinet Cooler to keep the VFD cool.  We went through our normal questions to determine the heat load, i.e. the size of the cabinet, the temperature inside, the temperature outside, the maximum external temperature and the desired temperature.  As we went through the questions, he stated that the cabinet was located outside.  This is not an issue for our Cabinet Coolers as EXAIR has NEMA 4 and 4X (IP66) Cabinet Coolers.  It did stem another question; was it under cover?  He mentioned that it was not.

Generally in calculating cooling capacities with our Cabinet Coolers, we size the units by adding the ambient heat load and the electrical heat load. With the panel exposed to the sun, this adds another component to the total heat load.  To get an estimation on the amount of solar heat, color becomes a big factor as the darker colors will draw more heat.  Here is a good approximation to follow:

In this application, the customer had a gray panel, a common color. With an exposed surface area of 16 ft^2 (1.47 M^2), we would have to increase the heat load by 16 ft^2 * 7 Watts/ft^2 = 112 Watts.  This equates to 112 Watts * 3.41 BTU/hr/Watt = 382 BTU/hr of added heat.  (Or 112 Watts * 0.86 Kcal/hr/Watts = 96 Kcal/hr).

If an electrical panel is outside and cannot be shaded from the sun, we can still protect the sensitive components inside.  With the proper sized Cabinet Cooler, your equipment will remain running cool.  If you need help to determine the correct Cabinet Cooler, inside or out, you can either contact an Application Engineers at 800-903-9247 or fill out our Cabinet Cooler Sizing Guide.

John Ball
Application Engineer
Email: mailto:johnball@exair.com

“The sun” image courtesy of Lima Andruška, https://creativecommons.org/licenses/by-sa/2.0

## Calculating and Choosing the Right Cabinet Coolers

“I need one of your Cabinet Coolers for my control panel, the dimensions are 24″ H x 30″ W x 16″ D, what do you recommend?”. This is a very common inquiry we receive when discussing our Cabinet Cooler Systems for the first time with a potential customer. While it would be nice if it was a simple as using just the dimensions, there is more that goes in to making the proper selection.

Following explains how to go about calculating and choosing a Cabinet Cooler System. If, at any time, you prefer EXAIR to calculate and assist with your choice – contact our Application Engineering department and we will be happy to get you up and running.

Our Cabinet Coolers are sized by cooling capacity in Btu/hr., which range from our lowest of 275, up to our largest Dual System providing 5,600 Btu/hr. Now if you know the Watts loss , we can convert this over to Btu/hr. (Watts X 3.41 = Btu/hr.). If you are unsure, we need to determine the current heat load of the cabinet by using the dimensions, current temperatures (internal and external) and worst case external temperature and the desired temperature you are looking to maintain inside the enclosure. To simplify this process, we offer our Cabinet Cooler Sizing Guide.

The current internal and external temperature will determine one of your ΔT’s (temperature differential), which is used to determine a multiplier from the table below. We then take your maximum external temperature and your desired internal temperature to give us another ΔT and multiplier. Use the sq. ft. of the cabinet and multiplying it by the temperature conversion multipliers. Add these sums together to determine the total heat load in Btu/Hr. This value will help you to choose the proper Cabinet Cooler system to solve your heat problem.

Now that we have the heat load properly calculated, we need to know the NEMA class of the enclosure. We offer NEMA 12 for general use where there aren’t any corrosives or liquids present, NEMA 4 for wet or damp environments and NEMA 4X for wet, corrosive applications.

We offer Thermostatically Controlled Systems with available voltages of 120VAC, 240 VAC or 24VDC. This is the most efficient means of operation as the unit only operates when the internal desired temperature is exceeded. In addition, we also offer Continuous Operating Systems, providing constant cooling and positive pressure into the cabinet. Each system  includes a filter separator for the supply line to keep water and dirt from entering the cabinet as well as duct tubing.

Of course, if you need any additional assistance, you can always contact one of our application engineers. If you can provide a little bit of information, we can do the calculating and get you on your way.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

## Summer Returns & So Does Heat Related Damage to Electrical Cabinets

Summer has not officially arrived in the Northern Hemisphere, according to the calendar, but temperatures have started to push 90 degrees Fahrenheit here in Cincinnati. As the temperatures increase, your electronics may start to feel the heat. High temperatures can cause circuits breakers to trip, controllers to shutdown, and connectors to be very sensitive.  We have seen electronics lose machine control, report bad readings, or if the heat is not managed promptly, damage circuitry. EXAIR Cabinet Coolers Systems are a simple, quickly installed and effective solution to heat related problems. Beside being installed in minutes and shipping from stock, they have additional benefits over fans, air conditioners and heat exchangers.

During the heat of the summer, fans, air conditioners, and heat exchangers may fail when you need them most.  For instance,  a fan and a heat exchanger work because the temperature differential between the ambient temperature and the inside of a cabinet is large. As the temperature rises, the ambient temperature goes up and a fan or heat exchanger lose their ability to remove heat from the cabinet. In a climate controlled environment this works great, in a hot plant floor without air conditioning, it is a recipe for failure.

So if fans aren’t a good solution you may turn to air conditioners in the summer because they can still produce very cold air at much higher ambient temperatures. You will need hours to install them, cross your fingers that they arrive undamaged, hope the condenser and other moving parts don’t fail and provide a drain for the condensate. If you are in a dusty environment, the filters will clog more often in the summer and require more maintenance. As the temperature rises the air conditioning systems run more often which means they pull in more air and particulate that will clog the filters and lead to reliability problems in the compressor. This compressor is subjected to more of a work load in the summer and more airflow restriction, if the filters are not changed often. This may lead to more air condition filters during the summer months.

EXAIR compressed air operated Cabinet Coolers System are a great solution for cooling enclosures. They operated via vortex cooling which requires no moving parts or filters from the outside air.  They drop your compressed air temperature 50 degrees Fahrenheit.  Mounting requires a compressed air supply, a standard electrical knockout, and the locknut that comes with the Cabinet Cooler System. The cooling is produced immediately with no lag time. A Electronic temperature controller is a available to maintain a temperature of your choosing.

Cabinet Cooler Systems are maintenance free with a clean dry supply of compressed air. Recently, we tested a cabinet cooler that was over twenty years old that still tested to our production standard.  The customer was delighted to hear that is was working so well they wanted it returned.  Cabinet Cooler Systems are available for NEMA 12, NEMA 4 and NEMA 4X enclosures. Kits include compressed air filtration to keep water, dirt and oil out of your enclosure. If you see an open panel door this summer, look into a Cabinet Cooler Systems. We can help you beat the heat.

EXAIR’s Cabinet Coolers are in stock and ready to ship to you same day if ordered by 3:00 pm EDT. You can have it tomorrow if you like.

Dave Woerner
Application Engineer
@EXAIR_DW
DaveWoerner@EXAIR.com

## Keep it Cool…And Clean…And Dry

Summer is in full swing for us in the U.S.  The temperatures and humidity are high, the sun is shining, and EXAIR Application Engineers are calculating heat load for overheating electrical enclosures to help customers determine which Cabinet Cooler system will remove the heat and eliminate associated problems. With the variety of applications for EXAIR Cabinet Coolers comes a variety of problem solutions.  For example, we may cool the temperature of an enclosure, and, we may also prevent dust or water from entering the enclosure.

This is exactly what EXAIR can offer in the application shown above.  As you can see, the enclosure has remained open in a dirty environment in an attempt to solve an overheating condition.  This, in turn, has allowed dirt from the surrounding area to enter the enclosure and infiltrate the electrical devices.  An attempt to solve one problem has created another.  By installing an EXAIR Cabinet Cooler, this end user is able to cool the electronic components AND keep the enclosure contaminant free, solving two problems with one device. Also note that keeping an electrical panel doors open exposes personnel to dangerous situations if they come in contact with the exposed wires and connections.

EXAIR Cabinet Coolers have the potential to end an overheating condition AND prevent dirt from entering the enclosure by creating a slight positive pressure inside the cabinet. There is no need to worry about water entering the enclosure if you are in a wash-down or high humidity environment because they are UL listed for NEMA integrities of NEMA 12, NEMA 4 and NEMA 4X. NEMA 12 integrity protects against dirt, dust, and oil. NEMA 4 integrity is dust tight, oil-tight, splash resistant and indoor/outdoor service. NEMA 4X integrity offers the same protection as NEMA \$ but is available in 303 and 316 stainless steel to provide for food service and corrosion resistance. To find out more about what an EXAIR Cabinet Cooler can do for your application, contact an Application Engineer.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE