No one needs to be told how much time, effort and of course money accompanies the systems needed to keep a business running smoothly. Ensuring that pricey electrical equipment, servers and security systems that drive production remain operational is no longer a secondary task. It is a critical business function, and even a matter of public and employee safety. Continue reading →
In industrial facilities, electronic equipment is frequently used for motor control and most machines are PLC controlled. This use of electronic equipment has increased electrical enclosure heat loads because of the high heat dissipation characteristics of electronic equipment. At the same time, electronic equipment is susceptible to malfunction if allowed to get too hot, so it is widely accepted that electrical enclosure temperatures are kept below 100 ºF (37 ºC) to limit the possibility of unpredictable behavior or failure that could lead to a plant shut-down.
The closed loop cooling cycle of an Air to Air Heat Exchanger makes it right for many applications where cooling solutions such as fans are unsuitable or when air conditioners are undesirable due to their larger size, higher noise levels and greater energy consumption.
Environmental and climate conditions can negatively affect electrical enclosures in several ways. Beside the negative effects of excessive heat, dust and dirt, and the formation of corrosion is an issue that can plague enclosures. Corrosion doesn’t form without a reason; excessive condensation is most often the primary contributor to the formation of corrosion within enclosures.
For the electrical components within the enclosure, the formation of corrosion can reduce electrical continuity and the lifespan of the electrical connections leading to short circuits and breakdowns.Continue reading →
To the outsider, the food and beverage industry operates in a benign and clean environment. Although this assumption is largely true, it requires that facilities are rigorously cleaned and high standards of hygiene maintained. Cleaning processes include the use of chemical disinfectants and washdowns to prevent pathogens accumulating on any surface. Since the introduction of the Food Safety Management Act, the FDA Code of Federal Regulations Title 21, Part 110 was updated and requires that equipment in manufacturing and food handling areas is constructed so it can be kept in a clean condition, even if it doesn’t come into direct contact with food.
Almost everyone involved in the maintenance of electrical enclosures has, at one time or another, faced problems with overheated electrical enclosures. In most instances, the obvious solution was to install or upgrade the cabinet cooling fan only to find that it didn’t work too well.
UL stands for Underwriters Laboratories in the United States, and the initials UL represent their mark of approval. UL has laboratories in several other countries, and in Canada their mark of approval is cUL.
Underwriters Laboratories belongs to a group of nationally recognized testing laboratories; organizations that are accepted by authorities having jurisdiction (AHJs) in terms of the US National Electrical Code to certify equipment as meeting certain specifications. In simple terms, the UL label in the USA and cUL label in Canada on electrical products indicate that the products have been designed, built, and tested to be in accordance with safety standards for those respective countries by Underwriter Laboratories. Although there are many obvious similarities, UL and cUL requirements for electrical enclosure cooling are not the same.
The Underwriters Laboratories UL mark applies to products that have been designed and approved for the US market and have received specific Underwriters Laboratories certification that they comply with the respective US standards. These are specified in ANSI/NFPA 70, the National Electrical Code and, more specifically, the ANSI/UL 484 standard for special purpose air conditioners.
The cUL mark applies to products intended for the Canadian market that have been tested and found to comply with the requirements of CAN/CSA 22.1-12, which is the Canadian Electrical Code issued by the Canadian Standards Association. Included in this code under section 22.2 are two sections, numbers 236-M90 and 117 that deal with heating and cooling equipment and special purpose air conditioners.
UL and cUL are Not the Same
The two marks are not the same and may not be used interchangeably. However, there are many similarities and equipment that has been tested under one standard may well comply with the other. Although the respective national standards have many similarities, it is important to note there are many detailed differences. For example, Canadian codes reflect a stronger European influence as can been seen in the frequent reference to IPXX enclosure protection ratings in Canada, although the US NEMA enclosure ratings are also used.
Obtaining UL and cUL Certification
Manufacturers who sell internationally need to obtain certification that gives them access to the US, Canadian, and other markets. It is costly to obtain certification from a testing laboratory and Underwriters Laboratories has prepared harmonized standards that can be used to design and manufacture equipment to comply with both the UL and cUL requirements. These standards are:
UL 50 Enclosures for Electrical Equipment: The standard is applicable to electrical enclosures intended for installation in terms of the Canadian Electrical Code, Part 1 (CSA 22.1), The National Electrical Code (NFPA 70), and Mexico’s Code for Electrical installations. There are some exceptions detailed in the standard.
When new products are introduced, or it is desired to obtain approval for existing products, Underwriters Laboratories is able to perform unified testing to verify compliance with the Canadian and US standards. This approach is a cost effective way to obtaining UL and cUL approvals.
Buy Electrical Enclosure Equipment That Meet Local Requirements
Many local authorities in the US and Canada require that electrical enclosures and enclosure air conditioners comply with national standards and carry an appropriate certification from a recognized testing laboratory. It should not be assumed that an item carrying a cUL mark is acceptable in the US or an item carrying the UL mark is acceptable in Canada. Thermal Edge’s range of enclosure air conditioners complies with the UL, cUL and CE (European) requirements thus meeting local authority requirements. Contact Thermal Edge for further information.
Many of the requirements found in the National Electric Code (NFPA 70) specify that electrical equipment to be installed in non-hazardous industrial facilities, such as wastewater treatment plants, food processing plants, and data centers, must be listed or labeled by UL or another standards testing agency.Continue reading →
As electrical components become increasingly smaller and are more densely packed into electrical control panels, the amount of heat generated inside cabinets continues to increase. When consideringheat dissipation in control panels it’s important to note what electrical equipment manufacturers specify as a maximum allowable operating temperature for their components.
Maintaining a maximum internal control panel air temperature of 95°F (35°C) helps promote higher operating efficiencies and longer electrical component life. It’s easy to overlook the importance heat dissipation plays in control panels and how it can affect electrical equipment reliability.
How Heat Dissipation Works in Sealed Unvented Control Panels
In order to protect against demanding environmental conditions most industrial applications will require sealed unvented control panels such as NEMA Type 12, 4, and 4X cabinets to protect the costly electrical components housed inside. Most applications will require a closed-loop cooling solution due to high ambient temperatures or to protect sensitive electrical components from excess dust and dirt.
While the heat producing electrical components increase the air temperature inside the control panel, the resulting heat is transferred through the walls of the cabinet to the cooler ambient air outside where heat dissipation occurs. If the ambient air were cold enough to maintain temperatures below maximum operating temperature for the electrical components, this would be a natural cost effective cooling solution, but this is rarely a viable option.
The overall cooling capacity needs to match or exceed amount of total heat load generated by the electrical equipment within the control panel when the ambient air temperature is lower than the cabinet air temperature.
How Heat Dissipation Relates to Control Panel Size
Besides ambient temperature, the physical size of a control panel is the primary factor in rate of heat dissipation. Larger control panels will have larger exterior surface areas, resulting in a lower temperature rise from the heat producing electrical components inside. Having an oversized control panel simply to increase the heat dissipation rate doesn’t make economic sense, since larger cabinets are more costly and may require excessive space.
The easiest method to calculate the surface area of the control panel is to use the following equation: Total Surface Area = 2(H x W) + 2(H x D) + 2(W x D), which includes all six sides of the control panel measured in feet. Any surface area not exposed to ambient air, such as wall mounted or free standing cabinet models without legs, must be subtracted from the total value.
Once the total surface area has been determined, the next step is to calculate the heat load produced by the electrical components.
Factoring in Heat Load Produced by the Electrical Components
The total heat load is established by adding together the heat dissipation of all individual components housed inside the control panel. This information can be obtained from the manufacturers of the electrical components and the resulting value is usually given in Watts.
Additional Heat Dissipation Factors to Consider
Although the heat dissipation calculation of a control panel is a simple one, the true impact of external influences can be more difficult to determine. The control panel’s properties such as color, material type and whether it is insulated or not must also be considered. Factors such as maximum ambient temperature, effects of local heat sources and solar heat gain must be included when calculating the control panel’s total heat load. The control panel’s properties such as color, material type and whether it is insulated or not must also be considered.
The combination of these factors, plus the heat dissipation and heat load values all play an important part in determining the associated cooling capacity requirements.
Heat Dissipation and the Enclosure Temperature Management Calculator
The ETM calculator will help determine whether the control panel cooling needs will require an air conditioner, an air to air heat exchanger or a filtered fan package. Additionally, results will show which size and type of air conditioner will provide the required cooling capacity offering the most energy and cost efficient operation.
Don’t Ignore Control Panel Temperature Control
Although the heat dissipation calculation of a control panel is a simple one, the true impact of external influences can be more difficult to determine.
Many electrical control equipment failures are caused by overheating due to improper control panel cooling, but could be avoided with proper temperature control planning. An excellent place to start is to download the free Thermal Management Guide: Meeting Control Panel Space Requirements and Avoid Overheating e-book to learn more about how to incorporate enclosure cooling into your design and keep equipment operating safely in a smaller control panel.
For additional help the experts at Thermal Edge are available to help you properly chose the correct control panel cooling system for your application.
It’s important that your electrical cabinet cooling system complies with relevant safety standards. Units purchased for use in the USA should comply with UL and NFPA standards and those for other regions and countries with appropriate national standards.
Additionally, US employers are required to comply with the General Duty Clause of the OSH Act that requires them to keep the workplace free of serious hazards. Compliance will ensure your cabinet cooling systems meet local safety requirements.