Thermal management is the monitoring and control of temperature produced by devices in electrical enclosures. Schneider Electric’s ClimaSys enclosure systems take the guesswork out of thermal management for electrical switchboards and control panels.
Thermal management is important as temperature affects the reliability and service life of electric and electronic equipment. When devices and installations in enclosures fail or malfunction, it’s often a thermal issue. The accepted guideline is for every 10° C. over rated temperature there is a 50% reduction in device life expectancy. (Arrhenius equation)
One device failure can affect a control cabinet and perhaps production-line reliability. The challenge for control panel builders is the number of variables in play. Careful and considered configuration of the cabinet by the designer will improve this. However, despite the design phase considering the working temperature range of each device, a control cabinet may suffer from overtemperature
Thermal management
The device arrangement inside the cabinet can often lead to hot spots. It is also the case that they often appear in places where infra-red cameras used to detect hot spots have little access, such as the back of the cabinet.
When internal fans on equipment stop working, they often have no alarms that alert the user to the failure. The resulting temperature increase can reduce their operational life and also age other nearby equipment. When a control cabinet is closed, it can be difficult to know what is happening inside with factors such as temperature, humidity and dew point. This is particularly true in harsh industrial environments.
If PLC’s, switches, variable speed drives, industrial PCs, contactors and other equipment exceed their normal working range, the entire system can enter a critical operational condition.
Good thermal management
Thermal management improves plant safety by preventing overheating from causing malfunctions and reduces equipment downtime. Further, it can prolong device service life and improve energy efficiency, lowering manufacturing costs and reducing maintenance cycles and costs.
A good starting point is to visit the site of the enclosure’s intended location, to assess weather conditions and air quality. The cabinet materials selected should be suitable for the site environment and lend themselves to heat dissipation. Depending on the sensitivity of the equipment installed, it may be appropriate to conduct a thermal balance analysis.
Also, the local environmental factors such as air temperature and desired operating temperature. Finally, the total power loss, i.e. the sum of the dissipation value of each device in the enclosure. Having established thermal balance, users enter parameters like humidity, air quality, and the degree of pollution in the thermal management program. The software (ProClima) then calculates the most appropriate thermal management solution.
Thermal management solutions
There are two kinds of solutions, passive and active: of these, passive is simpler and cheaper and usually considered first. Passive includes using larger enclosures, changing enclosure location, changing panel layout and adding grills for natural convection ventilation.
Active solutions use technology to control heat or heat-related effects. Also, they include using thermal control devices to control the selected option. Thermal management options include forced convection using fans, ventilators and air-conditioners or air-water and air-air exchangers. Depending on the environmental conditions, resistance heaters or dehumidifiers may also be appropriate.
Schneider Electric has introduced a diagnostic tool to improve reliability of the installed equipment. It provides thermal reports and reliable and proven thermal solutions for ventilation. Importantly, the ClimaSys DT tool enables reliability, energy efficiency, safety and lifetime support for critical production processes with severe downtime risks.
The ClimaSys DT comes with ProClima 7software which uses six algorithms to allow detection of environmental conditions inside a control cabinet panel. This data makes it possible to make processes inside the cabinet more reliable. Once connected, the datalogger generates a first PDF formatted report for sending to an e-mail address.
