Current ratings of the components in Europe is by monitoring the metal conductor temperature to determine when current is increased. When the PIN when the temperature is higher than the ambient temperature 45 ℃, surveyors will be current as the rated current of the device (or the maximum current value). IEC specifications, another is to allow current value, it is the largest current 80%. In contrast, UL standards will make the metal conductor temperature higher than the ambient temperature 30 ℃ current 90% as the value of the nominal value.
This shows that the temperature of the metal conductor section is a very important factor in all applications. This is more important for industrial equipment. Industrial devices often need to work at temperatures up to 80 degrees Celsius environment. If the wiring terminal block temperature is higher than the temperature of 30 degrees or 45 degrees, then the Terminal temperature of over 100 degrees. Nominal value type should be based on the selected devices and insulating materials, the product must be lower than the rated value of current work, so that they can work reliably in the desired temperature range. Sometimes, suitable for compact packaging materials may not be able to satisfy cooling requirements, use of this type of terminal devices must be much lower than the rated value of current. So, shows the importance of how to select a terminal type.
With globalization, we need to design systems that can be sold globally, so system designers are more and more frequent use of Terminal products made in other countries. As the euro nominal value measurement method, so lower than the nominal value and the use in design is common practice in Europe. However, many United States Designer is not familiar with this concept, and if they don't understand the differences between the standard, would be difficult in the design process
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