40 views Yuda Electronic (HK) Technology Co.,Limited. 2019-01-04
What does the nominal voltage and current of the power adapter mean?
First of all, the nominal voltage of the general power adapter refers to the voltage of the open circuit output, that is, the voltage when no external load is connected and there is no current output, so it can be understood that this voltage is the upper limit of the output voltage of the power adapter.
In the case where an active voltage regulator is used inside the power adapter, even if the mains voltage fluctuates, its output is constant, like a small transformer on the market, such as a power adapter such as MP3, if the mains voltage Fluctuations, the output of the power adapter will not fluctuate accordingly.
The true voltage of the ordinary power adapter is not necessarily exactly the same as the nominal voltage. Because the characteristics of the electronic components cannot be completely consistent, there is a certain error. The smaller the error, the higher the consistency requirement for the electronic components, and the cost of production is higher. so the price is more expensive.
In addition, regarding the nominal current value, regardless of any power supply has a certain internal resistance, when the power supply output current, it will internally generate a voltage drop, generate heat, so the power supply will be hot, and the other is to cause the output voltage to decrease. Equivalent to internal consumption.
Power adapter manufacturers have some quality questions, mainly:
1. The symbol is incomplete or not standard
The label should include the correct installation, correctly guiding the user’s important information to indicate the symbol of the product to ensure the safety of the user. The label should not be dropped and the content should be clear. The goods sold include the following information: the manufacturer’s or distributor’s title, trademark or identification symbol, type code or standard type, power supply properties, and additional power supply voltage scale.
2. Heating under normal conditions does not meet the demand
The conversion voltage of the power adapter requires power, which is due to the loss during the voltage conversion process. The radiation, convection, and conduction are converted into heat energy, and some of the heat energy is about to be distributed to the surrounding environment. Therefore, the temperature of the power adapter rises. Increasing the internal temperature of the equipment to a certain temperature will cause the insulation material to age and then reduce the safety.
Some products under normal conditions, the temperature of the circuit board and transformer windings of the commodity is too high, there is a great safety hazard. As a consumer, you should pay close attention to the temperature rise of the product. The simple method is to use the test article to raise the temperature of the outer casing. The temperature difference between the ambient temperatures does not exceed 60 ° C. Even in the hot summer days, the ambient temperature reaches. At 35 ° C, the shell temperature can not exceed 95 ° C, if the temperature of the product rises too high, we should stop using it in time.
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