Two important reasons for selecting terminal terminals
The application of power supply terminals has become a trend in electronic devices, and the power terminal devices themselves are also increasing, and can carry more power. As the terminals become larger, their importance in the function of devices is also more and more prominent. They also play an increasingly important role in ensuring product characteristics.
Current circuit board technology improved the terminal panel installed on the bearing and improve a lot, has broken through the limit of 110A, far more than the previous product level, which makes the design process in the end what kind of power supply terminals to meet the system requirements this problem becomes more complicated. In addition, the method of measuring performance parameters in different areas is different, and even the nominal parameters of the same product are quite different. Therefore, to obtain long-term reliability and ensure low cost, it is very important to understand these differences.
Engineers also have to consider another factor that is often overlooked, that is, marketing considerations. Usually, terminals are visible to users. Therefore, marketing departments often want products to match the color and style of the whole system in appearance.
The main factors that affect the selection of terminal terminals are introduced in detail.
1. power processing factors
One of the first factors to be considered is the power processing capability of the device. Reading the data handbook simply does not guarantee accurate comparative data. Engineers must understand how the product performance data listed in the manual are tested and determined.
At present, UL, IEC, CSA and DIN have no unified standard in determining the power and performance specifications of terminal products. The user needs to understand the differences between the UL and the IEC specifications. IEC standards are used in the specifications of terminal products made in Europe, while UL standards are used in the products made in the United States.
The differences between the two standards are very large. Engineers who do not know the method of determining the specifications of products will take considerable risks, because the selected devices may not reach the required power level, or the specifications of the devices are far beyond the design requirements. In Europe, the current rating of the device is determined by the temperature of the metal conductor when the current is monitored. When the temperature of the metal pin is 45 higher than the ambient temperature, the surveyor takes the current as the rated current value (or maximum current value) of the device. The other item of the IEC specification is the permissible current value, which is 80% of the maximum current. Unlike this, the UL standard will make the metal conductor temperature 90% higher than the ambient temperature at 30 C as the current nominal value of the device. It can be seen that the temperature of the metal conductor is a very important factor in all applications. It's more important for industrial equipment. Because industrial equipment usually needs to work at a temperature of up to 80 degrees centigrade. If the temperature of the terminal is 30 C or 45 C higher than that of this temperature, the terminal terminal temperature will exceed 100 degrees C. According to the nominal values and insulation materials selected by the selected devices, the products must be operated at a lower than rated value, so that they can work reliably in the desired temperature range. Sometimes, materials suitable for compact packaging devices may not well meet the heat dissipation requirements. Therefore, the current of such terminals is much lower than the rated value.
With the globalization of enterprises, we need to design systems that can be sold around the world, so system designers are increasingly using the power terminal products produced in other countries. Because of the use of nominal value measurement in Europe, it is a common practice for devices to be used in Europe for less than nominal values in the design. However, many American designers are not familiar with this concept, and if they do not understand the differences between the standards, it will be difficult in the design process.
Another factor that is often ignored in the selection of devices is the end - connection technology used by the product. Most power terminal products are still using through hole connection mode. This method provides the required mechanical support and ensures a solid electrical contact with the power layer embedded in the multilayer circuit board. There are many different types of pins used to connect the terminals to the circuit board. Some companies only provide single - pin models, while others provide multi - pin products. The advantage of multi pin products is that it can distribute the current more evenly to the circuit board, provide more reliable mechanical stability and improve solidity.
2. appearance factors
Though the name of "power connector" doesn't sound very beautiful, many companies think it plays an important role in the appearance of products and the affinity to users. The power terminals must be installed conveniently, as they are often installed on the front end of the easily seen product panel. In this way, the marketing staff often want to have a certain voice on the appearance of the power terminal products. But often this happens: engineers design products meet all mechanical and electrical parameters requirements, but because they do not meet sales requirements, they have to make changes. If this occurs at the end of the design cycle (often when the marketing department first sees the prototype), then a heated argument is inevitable, which may lead to higher cost and delayed delivery. In many industrial control systems, terminals are often one of the few components that the technicians need to pay more attention to. Although its user interface is relatively simple (mainly screw), it is positive for the device.