Will an Enclosure Cooling Fan Protect Your Electrical Equipment?
Industrial electrical equipment is vital to the operation and success of many businesses, yet the wiring and components contained in an electrical enclosure may be subject to degradation from excess heat, as well as from dirt and dust, splashing liquids, wet weather, and corrosive chemicals.
It’s important to select the correct enclosure cooling system, one that will keep cooling costs low and minimize maintenance requirements, yet provide sufficient protection.
An enclosure cooling fan is a low-cost option that can properly protect electrical equipment, depending on the type and location of the enclosure and the amount of heat generated by the components inside.
Filtered Fan Considerations
Though a filtered fan cooling system might be an ideal solution in some cases, it does have drawbacks. Because fans pull outside air into the enclosure, they require a filter to provide protection from dust and dirt in the ambient environment. Filtered fans also add to your maintenance requirements. If not properly cleaned at regular intervals, the increased air resistance of accumulated dust and debris will reduce a fan’s cooling capacity.
Another factor to consider is that an enclosure cooling fan cannot provide adequate cooling in cases where the ambient air temperature gets too high, or when the electrical equipment generates too much heat. Fans work through forced convection cooling, in which the action of cooler outside air flowing over the heated equipment increases the natural thermal exchange. The difference between the enclosure and ambient temperatures (Delta T) must be large enough to provide sufficient cooling.
A final consideration for selecting a filtered fan system to cool your enclosure is the National Electrical Manufacturers Association (NEMA) rating of the enclosure.
Determine the NEMA rating
The NEMA rating system for an electrical enclosure is based on how it is made and where it is located. Determining the rating of your enclosure is a critical step toward selecting the proper type of cooling system to protect your electrical equipment.
Generally, enclosures with one of the following two NEMA ratings can be sufficiently cooled with a filtered fan:
NEMA Type 1
NEMA Type 1 is an enclosure mounted indoors in an area that is not excessively heated by ovens or other equipment. This type of enclosure provides some protection from dust or particles, but not from splashing water, chemicals, or airborne contaminants.
NEMA Type 3R:
NEMA Type 3R is a weatherproof enclosure that can be used indoors or outdoors. This type of enclosure is sealed to protect the equipment from rain, snow, and ice, and provides some protection from falling dirt, but not from windblown dust, direct water sprays or corrosive elements.
Other NEMA enclosure ratings, including Type 4, Type 4X, or Type 12, require a different cooling technology, such as an air to air heat exchanger or an enclosure air conditioner, which remove more heat and provide more protection from dust, moisture and chemicals than a filtered fan.
Determine the cooling capacity required
Once you have determined that a filtered fan can effectively protect your electrical enclosure, you then need to calculate the cooling capacity required for the fan. This will depend on the amount of heat generated by each piece of equipment in the enclosure (internal heat load), and Delta T (remember, the ambient temperature must be lower than the internal temperature).
To find the cubic feet per minute (CFM) of airflow necessary to fully protect your electrical equipment, it is best to use an online BTUH Calculator. Then triple this number to account for air resistance of the inlet and exhaust filters and determine the free flow rate for the fan.
For help in determining the right cooling solution for your electrical enclosure, contact one of the experts at Thermal Edge today.