Overcurrent protection for regulated power adapter
In a series regulated power adapter , all load currents must flow through the pass transistor. When an overload occurs, a large-capacity capacitor is momentarily charged or the output terminal is short-circuited, a large current will flow in the pass tube. Especially when the output voltage is accidentally short-circuited, all input voltages are added between the collector and emitter poles of the series regulator tube, so that the heat generation in the tube increases sharply. If proper protective measures are not taken, the tube will be burned immediately. The thermal inertia of a transistor is smaller than that of a fused fuse, so the latter cannot be used to protect the former. Fast response electronic protection circuits must be used to protect the series pass transistor. Electronic protection circuits can be divided into two types: current-limiting type and current-cutting type. The former limits the current of the pass tube to a certain safe value, while the latter cuts off the current of the pass tube immediately when an overload or short circuit occurs at the output.
The stabilized DC power adapter will generate a strong negative high voltage, and then connect one section of it to the cathode and one section to the anode, and then generate a strong electric field between the cathode and the anode. After the electric field of the two poles exceeds the specified strength, it will discharge. Ionization occurs around the electric field, and a large number of electrons and ions are generated. After a while, you can hear a strong electromagnetic wind sound around the electric field. The faint violet corona can be seen in the dim light. And around the electric field, there will be a lot of tar, dust and other particles combined with ions or electrons. This charge will move to the poles under the action of the electric field force. The mass of the electron is particularly small, but its movement speed is particularly fast, so it is mainly carried by negatively charged particles.
The article is reproduced from the Internet. If there is any infringement, please contact to delete it.
|| Release time: 2019.11.13 Source:|
|Previous: Common faults caused by power adapter and battery problems||Next: How to repair the power adapter|
Dongguan Qiqi Industrial Co., Ltd. specializes in producing: power adapters , chargers, LED drive power supplies, car chargers, switching power supplies, etc ...