Protecting Control Panels in Outdoor Environments

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  • A Revolutionary Technology Extending the Ultra-Broad Functionality

    of Ethernet

    February 2015 Environmental: Outdoor Protecting Control Panels in Outdoor Environments

    www.pentairprotect.com www.panduit.com

    White Paper

    http://www.pentairprotect.com/http://www.panduit.com/

  • PUAT03- -WW-ENG, Rev.0, 02/2015 2015 Panduit Corp. and Pentair Equipment Protection. All Rights Reserved.

    2

    Protecting Control Panels in Outdoor Environments

    Introduction Outdoor environments create multiple sources of risk for equipment failure within control panel enclosures. For example,

    enclosures located outdoors must withstand potential ultra-violet (UV), solar heat, rain, hurricanes, earthquakes, and

    tornadoes. These harsh elements create unique reliability and protection needs for applications such as solar combiner boxes,

    mobile telecommunications, outdoor industrial controls, traffic toll systems, railway signals, and outdoor electrical junctions.

    Along with the environmental risks created by adverse climates, it is important to consider the relevant technical factors, such

    as ingress requirements, chemical presence, Electromagnetic Interference (EMI) and standards, when selecting a control

    panel for outdoor use. Determining whether the enclosure needs a cooling system, corrosion resistance, and a water or dust-

    tight seal will allow design/controls engineers to select the proper enclosure and material to provide the appropriate level of

    equipment protection against the elements.

    Although it is sealed off from intense weather conditions, the internal assembly of the control panel must also be designed for

    harsh conditions, such as extreme temperature variations. This and other dynamic factors (e.g., moisture, condensation,

    chemicals, and corrosive gases) can affect internal component and material selection, panel layout and design, and the need

    for environmental conditioning (cooling and/or heating).

    This white paper is one of three papers that collectively address the environmental protection of control panels. The intent is to

    review and provide guidance on the risks and solutions available for outdoor environmental applications. For additional

    information on this topic, including copies of the white papers as they become available and more information on Panduit or

    Pentair Equipment Protection (Manufacturers of the Hoffman brand of enclosure), please visit www.Hoffman-Panduit.com.

    The Toll of Mother Nature on Control Panels Environmental elements that have a harmful effect on control panel reliability and performance include precipitation,

    dust, and seismic activity.

    Precipitation

    Water damage is one of the more common issues that plague electrical equipment. Differences in ambient air temperature can

    cause condensation to form, increasing the risk of equipment failure and short circuits. Condensation can also form as the

    temperature cools at night or when the equipment is shut down. In especially wet or humid applications, moisture can enter

    when a door is opened for maintenance or service purposes.

    For the internal components and wiring connections within the control panel, moisture and corrosion can affect continuity and

    the lifespan of the connections. It is essential to select corrosion-resistant materials to maintain continuity where moisture is

    likely to be present. It is also important to inspect critical electrical connections to the panel, such as power and grounding and

    bonding connections, for signs of corrosion.

    For help when evaluating the environment for climatic conditions, refer to:

    TIA TSB-185, Environmental Classification (M.I.C.E.) Tutorial

    IEC 60721-1 - 3, Classification of groups of environmental parameters and their severities

    http://www.hoffman-panduit.com/

  • PUAT03- -WW-ENG, Rev.0, 02/2015 2015 Panduit Corp. and Pentair Equipment Protection. All Rights Reserved.

    3

    Protecting Control Panels in Outdoor Environments

    Dust

    Dust or accumulation of other combustible particles (such as coal dust) within an enclosure drastically increases the chance of

    equipment overheating, fire, or catastrophic failure. Non-combustible dust, dirt, and other particles also reduce the integrity of

    the equipment. Solar heat accelerates these issues. However, selecting a proper location, material/rating, cooling system, and

    color may alleviate ignition concerns.

    Regarding ingress, failure can occur where accessory devices or cable connections are made through the panel. These

    components should match or exceed the enclosure rating to properly seal out dirt, dust, and particles, and maintain the

    control panels ingress rating.

    Seismic Activity

    Seismic-rated enclosures are needed in areas where earthquakes or other vibrations occur, such as power plants,

    airports, and railroads. For these environments, it is important to select an enclosure with the proper frame strength

    and rigidity to ensure the equipment does not become over stressed or damaged.

    Choosing the Right Enclosure for the Right Outdoor Environment Enclosure ratings define the types of environment where an electrical enclosure can be used and specify how well an

    enclosure can tolerate certain environmental conditions. Refer to the Environmental Protection of Control Panels:

    Overview and Standards Compliance white paper on Hoffman-Panduit.com for more information on enclosure ratings.

    NEMA Type 3R

    NEMA Type 3R enclosures are primarily used outdoors for protection against rain and sleet, and can withstand damage from

    ice formation. When substance infiltration is a concern but other requirements do not allow an enclosure to be completely

    watertight, a 3R rated enclosure offers an adequate level of protection. However, openings for vents, louvers, fans, air

    conditioners and other accessories can create an avenue for water or dust to enter the enclosure. While the 3R enclosure is

    rated for protection against rain, sleet, ice or other infiltration, without additional safeguards, abnormal conditions or events

    could damage the equipment.

    Due to the physical restrictions needed to maintain

    protection against the ingress of water, an enclosure can be

    vulnerable to extreme temperatures and heat load produced

    by the equipment. Inside a cabinet, uncooled components

    can generate trapped heat comparable to heat generated by

    a home furnace. AC power supplies, controllers, drives and

    servos, transformers and rectifiers, along with radio

    equipment and processors or servers are sources for this

    heat load. To help release heat produced, vents or louvers

    are allowed on a 3R enclosure but limitations may prevent full

    air movement, exhaust, or the exchange of heat. See Figure 1.

    Through the Arrhenius Equation, research has shown that for every 18F above normal room temperature, the reliability of

    electronic components is reduced by half. A more densely packed enclosure will require a larger, more powerful solution to

    resolve airflow problems. Without additional mechanisms for air movement, heat stratification within an enclosure increases

    greatly, causing hot spots and raising the potential of overheating or malfunction.

    Figure 1: Depending on the configuration of the components inside, airflow can be restricted by static pressure, increasing

    the temperature.

  • PUAT03- -WW-ENG, Rev.0, 02/2015 2015 Panduit Corp. and Pentair Equipment Protection. All Rights Reserved.

    4

    Protecting Control Panels in Outdoor Environments

    NEMA Type 4 and 4X

    NEMA Type 4 enclosures resist corrosion, protect against rain, sleet

    and ice formation, but also safeguard equipment from splashing, hose

    directed water, and windblown dust. In addition to the typical rain,

    sleet, or ice hazards, NEMA Type 4 and 4X enclosures must exclude

    at least 65 GPM of water from a one-inch nozzle at a distance within

    ten feet for five minutes. These rigorous standards are typical in

    outdoor locations such as ships, docks, and piers. Improperly installed or

    modified enclosures increase the risk of interior equipment damage. A single exposed opening can lead to the failure of the

    equipment, causing an increase in costs, resources, and time.

    Enclosures in extreme environments without proper heating and cooling elements have seen catastrophic failures in their

    equipment, de-rated drive performance, and changes in silicone material properties. See Figure 2. Integrated circuit devices

    can intermittently fluctuate in output, voltage migration, and decrease exponentially in mean time between failure. These

    problems increase missed shipping dates, labor costs, scrap, and component costs, while productivity and customer

    satisfaction decrease.

    Applications requiring NEMA 4/4X, (e.g., completely watertight enclosures and corrosive environments), create an even

    greater concern regarding heat load. The watertight necessity of the enclosure does not allow louvered venting and further

    limits the options to reduce heat load.

    Additionally, 4X stainless steel enclosures absorb and conduct heat better than non-metallic enclosures. While stainless steel

    enclosures improve heat dissipation issues better than non-metallic enclosures, they are inferior insulators. This causes

    additional challenges with UV or solar heat penetrating an enclosure. Non-me