The current rating of components in Europe is determined by monitoring the temperature of the metal conductor as the current increases. When the temperature of the metal pin is 45 °C higher than the ambient temperature, the measuring personnel will use the current at this time as the rated current value (or maximum current value) of the device. Another item of the IEC specification is the allowable current value, which is 80% of the maximum current. In contrast, the UL standard will make the metal conductor temperature 90% higher than the ambient temperature as 90% of the current value of the device as the current nominal value of the device.
It can be seen that the temperature of the metal conductor portion is a very important factor in all applications. This is even more important for industrial equipment. Because industrial equipment usually needs to work in an environment with temperatures up to 80 °C. If the temperature of the terminal block is 30 ° C or 45 ° C higher than this temperature, the temperature of the terminal will exceed 100 ° C. Depending on the type of nominal value and insulation used in the selected device, the product must operate at a lower than rated current to ensure reliable operation over the desired temperature range. Sometimes materials suitable for compact packaged devices may not meet the thermal requirements well, so the current used in such terminal devices must be much lower than the rated value. In this way, the importance of how to select the terminal type is reflected. As companies become more global, they need to design systems that can be sold globally, so system designers are increasingly using terminal products produced in other countries. Since Europe uses nominal measurement methods, it is common practice in Europe to use devices below the nominal value in design. However, many American designers are not familiar with this concept, and if you don't understand the differences between standards, it will be difficult in the design process.
Post time: Jul-21-2018