The Ambient Environment & Industrial Control Panel Reliability
The environment of an industrial control panel has a significant effect on system reliability and should be carefully evaluated during the control panel design stage. Environmental aspects that affect industrial control panels include ambient temperature, contamination, corrosion and vibration, and different strategies are required to ameliorate their effects. These include the installation of effective cooling systems, methods to prevent equipment contamination, corrosion protection and steps to reduce the effects of equipment vibration.
The cumulative effects of the environment where industrial control panels are installed are gradual and insidious. Initially, most items of electrical equipment will appear to function perfectly normally, but over time reliability will be affected as components are damaged by environmental influences and ultimately fail.
Environment influences affect equipment reliability in the following ways:
The effect of temperature on electrical equipment is often underrated, especially as there are many examples of electrical equipment that performs well in harsh environments such as those found under automobile hoods. The unfortunate reality is that industrial components are not built to withstand these conditions and most are vulnerable to failure at much lower temperatures. Equipment life is severely affected if manufacturer’s recommended operating temperatures are exceeded, and many types of electrical equipment will malfunction when exposed to high temperature.
Dirt and dust contaminate equipment by clogging moving parts and preventing contacts from operating, leading to overheating. Water, snow and ice may get into enclosures and damage equipment insulation, causing component failure.
Chemical vapors and salt air cause corrosion of metal components, making equipment fail and also causing unsightly control panel corrosion.
Equipment installed on moving equipment and flexible structures can suffer from severe vibration, leading to metal fatigue and consequent fracture. Enclosure air conditioner piping systems are particularly affected.
Steps To Mitigate Environmental Influences
These negative ambient environmental influences are more common than would normally be expected and even affect indoor installations. Fortunately, it’s possible to design industrial control panels and their associated cooling systems to reduce the negative impact:
Control panel cooling
Various cooling solutions are available. The first step would be to assess the total heat load in the enclosure and establish how that heat may be removed. Solutions include the use of natural ventilation, fan assisted cooling, and closed loop cooling solutions using heat exchangers or air conditioners.
Airborne dust and dirt must be kept away from equipment inside an electrical control panel and not allowed to block filters installed in air circulation systems. Depending upon the dust load, it may be possible to use filtered fan systems.
Enclosure dust sealing
If the dust levels are excessive, a NEMA 12 sealed enclosure fitted with a closed loop enclosure cooling solution designed for use in dusty environments is required. It’s crucial not to overlook the need for high-capacity air filters on the condenser systems of air conditioners used in dusty environments. Alternatively, an air to air heat exchanger could be used as the novel design of these units does away with the need for air filters.
Sealing against water
If the ambient environment is wet, a solution that is designed to exclude water is necessary. If the amount of water is high enough to cause excessive splashing or high pressure water sprays are used, a NEMA 4 rated enclosure would be required to prevent water ingress.
In the presence of corrosive chemicals, vapors and salt spray, the enclosure and cooling system design should be designed to prevent the ingress into the enclosure of such vapors. A NEMA 4X stainless steel housing for the cooling system is generally required and protective coatings should be applied to the copper components.
If severe vibration is present, the equipment in the control panel should be braced against the effects of vibration, and cooling systems such as enclosure air conditioners specially adapted to cope with vibration.
Choosing the Right Equipment for the Environment
The potential variations in the ambient environment for industrial control panels are such that there is no one solution that suits every requirement. If you need help selecting equipment for a difficult environment, speak to our Thermal Edge technical experts and obtain professional advice on protecting and cooling your industrial control panel.