The power handling factors that should be considered in the selection of terminal blocks. At present, UL, IEC, CSA and din do not have a unified standard when determining the power and performance specifications of terminal products. Users need to understand the differences between UL and IEC specifications. The specifications of terminal products manufactured in Europe adopt IEC standards, while products manufactured in the United States adopt UL standards. The difference between the two standards is very large. Engineers who do not understand the product specification determination method will take considerable risks, because the selected devices may not reach the required power level, or the specifications of the selected devices far exceed the design needs. UL standard takes 90% of the current value when the metal conductor temperature is 30 ℃ higher than the ambient temperature as the nominal current value of the device

Thus, the temperature of the metal conductor is a very important factor in all applications. It is more important for industrial electrical equipment. Because industrial electrical equipment usually needs to work in an environment with a temperature of up to 80 ℃. If the temperature of the terminal is 30 ℃ or 45 ℃ higher than this temperature, the temperature of the terminal will exceed 100 ℃. According to the nominal value type and insulating material used by the selected devices, the products must operate at a current lower than the rated value, so as to ensure that they can work reliably within the desired temperature range. Sometimes, materials suitable for compact packaging devices may not meet the heat dissipation requirements well, so the current of such terminal devices must be much lower than the rated value

Another factor often overlooked in the selection of terminal devices is the termination technology used in the product. Most power terminal products still use through-hole connection. This method can provide the required mechanical support and ensure solid electrical contact with the power supply layer embedded in the multilayer circuit board. There are many different types of pins used to connect terminals to the circuit board. Some companies only offer single pin models, others offer multi pin products. The advantage of multi pin products is that it can make the current more evenly distributed in the circuit board wiring, provide more reliable mechanical stability and improve the firmness of welding