Over the past few years, it’s quite clear that components within high power control panels have got smaller, this is down to the challenges imposed by clients wanting smaller enclosures to fit within much smaller spaces. With often huge amounts of terminals, wiring, circuit breakers, RCBO’s and much more general electrical components packed tightly into panel trunking up against core high power components such as variable frequency drives, motor starters and programmable logic controllers, quarters can be crowded resulting in an increased ambient heat load surrounding the enclosure due to restricted airflow and a high density of heat producing equipment. This happens when packing components within the enclosure more densely reduces the circuit sizes and increases speed but leaves little in the room for heat dissipation. This makes it even more important to protect these often-expensive electronic components from the excess heat especially as it is reported that for every 10 degrees C rise in temperature, the reliability of electronic components reduces by 50%! Learn more about heat dissipation calculations here.
In most circumstances where space is at a premium, the option to add a side mounted air conditioner is simply not an option. So, designers now opt for the build-up, not out mantra to tackle these issues. Natural ventilation is clearly not an adequate approach to today’s smaller high-power, high-density control panels, so a forced ventilation method using inexpensive filter fans and exhausts is the initial approach to ventilation. Ensuring that the internal temperature is lower than the ambient outside temperature is at the core of ensuring the proper operation of electrical components and effective heat dissipation.
High-power, densely packed control panels, however, may need more than a simple filter fan and thermostat to ensure their cooling reliability. With such a densely packed enclosure, the airflow that the fan can deliver is impaired due to the added resistance of the components all near to each other within the panel. A top mounted exhaust fan can usually provide a much-needed solution to pull hot air out of the enclosure and exhaust out to the atmosphere above when a higher airflow is required. Backward curved fans act as the workhorse within these units, but occasionally the heat load coupled with the high-power nature of the panel mean more than regular top mounted enclosure systems are needed.
Higher power, higher pressure and higher airflow backward curved plug fans regularly used in other industrial applications of air movement such as air handling systems, providing air to huge buildings, are a much better performance option that can maintain a small position on the top of an enclosure and ensure the enormous amount of heat generated is dissipated effectively. As an example, a high performance motor control centre within the water treatment industry could require a suitable cooling option to handle a 9400m3/hr flow rate at 400 Pascals with the option of speed control. Something a regular enclosure cooling solution would not be able to handle. With no wriggle room on the Delta T, backward curved plug fans can achieve the max duty required for this application with a bottom to top flow of air. The use of high-powered industrial fans such as the EC energy efficient GKHM EWheel with backward curved impellers, in these situations means that designers can incorporate the same larger drives they’re used to, ensuring accurate power distribution with the added benefit of being speed controlled. Speed control functionality ensures that the system maintains a constant airflow throughout or provides a simple method to adjust the speed of the fan, allowing for additional technology to be added or removed as required while still ensuring effective cooling.
In summary, smaller, tightly packed enclosures will continue to be a challenge for control panel designers and installers alike, with customers demanding the same performance with a much tighter floorplan configuration. Rapidly rising temperatures, thermal runaway and increasing control failures will become a problem that specifiers must overcome by assessing the exact location, size and placement of the enclosure before deciding on internal components and cooling capabilities, but at least through the use of more industrial technology, we can see an option to manage heat dissipation when high power and small spaces conflict with one another.
To learn the basics of thermal management, visit pbsi to read our informative article.