Make sure your enclosures are summer ready

10 July 2017

High temperatures are the most common cause of sensitive electrical and electronic components tripping or even failing, so users of manufacturing automation systems need to ensure that they are prepared for the summer heat and, if necessary, should arrange for an inspection of their equipment to check the level of risk, according to Jason Swann.

Electrical equipment generates lots of heat.  Add to this the ambient heat from the rising summer temperatures and your enclosure will start to reach a critical point of overheating without sufficiecnt cooling. What would you do if the equipment that manages your production line - your PLCs, drives and controls - failed due to inadequate or inappropriate cooling?  Can you afford to take the risk.”

Inverter drives are used within electrical equipment because they are effective at reducing the amount of energy used – which means lower production costs. Assuming an efficiency of 97%, a 250kW drive can produce up to 7.5kW of heat, much of which is retained inside the enclosure. Therefore without adequate cooling heat will rise.

The life expectancy of components is hugely affected by excess heat.  An electrical component’s life expectancy can be reduced by 50% for every 10°C increase in the ambient temperature. So keeping an Inverter drive cool will prolong its life, reduce the risk of failure and save money.

Rittal offers the following list of questions to check if there may be a problem brewing:  

• Is your equipment tripping or failing due to high temperatures?  
• Is this having an impact on production, in that it’s either slowing or stopping completely?  
• When you walk around your shop floor, do your enclosures feel hot to the touch?  
• At the height of summer, are your enclosure doors regularly left open and do you need large fans blowing into your panels to cool the devices inside them? This also presents a health and safety risk! 
• Does inadequate chilling of process fluids result in production down-time? 
• Would your existing cooling solution benefit from a health check?

Any ‘yes’ responses suggests a thermal survey could be a sensible next step.  Rittal’s expert team can provide a RiAssure3 survey and if necessary advise on the best solution. 

A RiAssure3 survey will identify the likely risk of a system overheating. It will review any existing cooling solution and determine how suited it is to that particular working environment. If necessary, it will then provide recommendations around remedial action – for example, changes to the system’s service and maintenance regime to help improve its efficiency or the recommendation to invest in different climate control technology.

Protecting equipment
Which cooling solution is installed will ultimately depend on the amount of heat produced inside the panel and the environment in which it is installed.  It must be specific to a particular application.

The main considerations centre around whether the enclosure is located in a cold or hot environment, if that environment is clean or dirty, and to what degree. Conditions may also change over the course of the working day, week, month or year, so the final selection of an appropriate cooling solution may not be entirely straightforward.

Enclosures that are placed in a cool and clean environment may find fan-and-filter units are more than adequate, given a single device provides more than 4 kW of cooling in ideal conditions.  However If the air is dirty, it is still possible to take full advantage of low ambient temperatures by using energy efficient air-to-air heat exchangers to provide any necessary cooling. For applications that require the temperature inside the enclosure to be lower than that outside it, a refrigerant based solution may be the best option.

The Blue e+ cooling unit range from Rittal, with capacities up to 6kW, can operate in ambient temperatures up to 60°C yet also provide free cooling when the external air is cooler due to its innovative use of hybrid technology. Air-to-water heat exchangers can be used in even hotter conditions and the water delivered to a remote location in which the heat, up to 10kW from one unit, may be dissipated more effectively and with less effect on the temperature of the surroundings. 

Jason Swann is Rittal’s product manager for Climate.

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