6 Thermal Hazards that Can Be Avoided in Control Panels
Enclosed industrial control panels are generally comprised of an electrical enclosure, internal components such VFDs, PLCs and other electrical equipment, which are mounted in various ways throughout the enclosure. Integral to the design and manufacturing processes, every component of these units and assemblies is evaluated for quality, durability, current ratings and the abilities to function safely within specified voltages.
Once assembled and in place, control panels are inspected for electrical, fire and shock hazards but usually not for their ability to operate reliably under high heat loads while surrounded by high ambient temperatures. The control panel designer is the sole person responsible for taking into account environmental factors, layout of electrical components and cooling management solutions in order to avoid thermal hazards and ensure safe and reliable operation.
The best way to ensure safe and reliable control panel operation is to be to avoid these potential problems:
1. Neglecting nearby heat-producing equipment
The ambient temperature range is an important factor to know before determining the correct cooling solution. The maximum ambient temperature may be higher than expected due to the control panel’s proximity to nearby heat producing equipment and/or exposure to solar radiation.
2. Improper arrangement of electrical components
Take advantage of natural convection by mounting heat sensitive electrical components towards the bottom of the control panel where the cooler air will be. Robust electrical components should be placed toward the top of the control panel since that is where the heated air will rise to. This arrangement will help protect temperature sensitive equipment.
3. Using an enclosure that is too small
Selecting a larger enclosure will provide more spacing between components allowing for better heat dissipation which will improve the overall control panel cooling. Choosing an enclosure with more depth can also provide better unrestricted flow of cool air, keeping hot spots from forming.
4. Inaccurate Heat Load Calculation
Conducting an accurate heat load calculation by using an online enclosure thermal management Calculator is a great place to begin before determining the required cooling capacity to ensure proper control panel protection. The proposed location and environmental conditions also determine the required NEMA rating of the enclosure.
5. Failing to monitor equipment
Establish cooling Performance performance Monitoring monitoring for enclosure air conditioners. Having this function in place will alert personnel before a thermal hazard occurs.
6. Condensation: An Often Overlooked Thermal Hazard
Thermal hazards for control panels are not always about overheating problems. Besides excessive ambient temperatures, equally catastrophic results can occur when ambient temperatures quickly fall in high humidity areas resulting in condensation. Besides rust, corrosion and short circuiting are the two major problems associated with condensation inside control panels. Corrosion causes increased electrical resistance, inconsistent equipment performance leading to component failure and unplanned downtime.
Condensation occurs when internal warm moist air comes into contact with the cool walls of the enclosure, which is at or below the dew point. Water droplets will begin to form and may come into contact with active electrical components. Exposed un-insulated enclosures located in outdoor environment are especially prone to condensation.
Condensation can be prevented the following ways:
- A properly sealed cabinet equipped with gaskets and cable grommets helps keep warm moist ambient air from entering the control panel.
- Avoiding frequent opening and closing of panel doors will help prevent condensation by limiting the amount of moist air entering the cabinet.
- Use a closed loop cooling system. Condensation is preventable by keeping the relative humidity 60% or less and controlling sudden temperature changes with the use of an air-to-air heat exchanger or an enclosure air conditioner.
- Use an enclosure heater. When the enclosure temperature falls below the ambient temperature and the air conditioner is not running, an enclosure heater can be used to maintain an air at a temperature that will allow it to absorb any moisture and keep it from condensing. Air conditioners are available with built-in heaters and separate heaters are also available for installation inside the enclosure.
Experienced specialists will work closely with you to solve cooling challenges that your industrial application poses for your electrical control panels. Contact us today to discuss your control panel thermal management plans.
