The first power wiring terminals will be stable transmission security wiring and signal to achieve the reunification. With the popularization of automation equipment, power supply terminal has become a mainstream trend, the continuous improvement of technology makes the terminal bearing more power. With the terminal volume change, whose importance in the equipment function is more prominent, and play more and more important role in ensuring the product characteristics. Current circuit board technology is constantly improving the terminal panel mounted bearing and improve a lot, at present has broken through the limit of 110A, far more than the previous product level, which makes the design process in the end in which a power supply terminal to meet the system requirements of this problem becomes more and more complex. In addition, the method to measure the performance parameters in different regions have different, even the nominal parameters on the same product are also has the quite big difference. Therefore, wants to obtain long-term reliability and guarantee low cost, understanding these differences is very important.
The engineer must also consider another often overlooked factors, namely marketing considerations. Generally, terminals are visible to the user, so marketing department often hope that the product can be matched with the whole system of color and style in appearance. The following specific to introduce the important factors influencing the terminal selection.
A processing, power factor
First of all, one of the factors to consider is the power handling capability of the device. Simply read the data sheet does not guarantee access to accurate comparative data. Engineers must understand the product performance data of the listed in the manual test is how to determine the. At present, UL, IEC, CSA and DIN and other institutions in determining the power and performance specifications of the terminal product and there is no uniform standard. Users need to understand the difference between UL and IEC specifications. Using the IEC standard in the making of Europe terminal product specifications, and in USA manufacturing products using the standard UL. There are wide variations between the two criteria. Do not understand the determination method of product specifications, engineers will take a considerable risk, because the selected device may not reach the power level required, or use the device specifications far beyond the design needs. In Europe, the current rating devices by monitoring the current value is increased when the metal conductor temperature to be determined. When the metal pin temperature 45 C higher than the temperature of the environment, measuring staff will then current as the rated current of the device (or the value of the maximum current value). Another of the IEC specification is to allow the current value, it is the maximum current of 80%. In contrast, UL standard will make the metal conductor temperature of 30 C higher than the temperature of the environment when the current value of 90% as the current value of the nominal device. Thus, the metal conductor portion of the temperature is a very important factor in all applications. This is more important for industrial equipment. Because industrial equipment often need to work in the environment of high temperature of 80 DEG C in. If the terminal temperature higher than the temperature of 30 DEG C or 45 DEG C, then the temperature will exceed 100 degrees C terminal. According to the nominal value types and the insulating material is selected by the devices, products must be lower than the current work of the rated value, so as to ensure that they can be at the desired temperature ranges work reliably. Sometimes, suitable for compact package device materials may not be good to meet the cooling requirements, so the current such terminal device when in use must be substantially lower than the rated value.
In the choice of devices, another factor is often ignored is the use of the products of the termination technique. Most of the power connecting terminal products are still in use connection through hole. This method can provide the required mechanical support, and can guarantee the power supply and embedded in the multi-layer circuit board layer to keep solid electrical contact. But to the wiring terminals are connected to the circuit board of the pin has a variety of different types of. Some companies only provide single pin type, others provide multi pin products. In the multi pin product advantages: it can make the current distribution to the circuit board more evenly to walk the line, provide mechanical stability more reliable and improve the firmness of welding.
Two, appearance factors