Summary of overcurrent protection experiment

In the series regulated power adapter, all load current should flow through the regulating tube. In case of overload, instantaneous charging of high-capacity capacitor or short circuit at the output end, a large current will flow through the regulating tube. Especially when the output voltage is inadvertently short circuited, all input voltages are added between the collector and emitter poles of the series adjustment tube, resulting in a violent increase in the heat generation in the tube. At this time, if there are no appropriate protective measures, the pipe will be burned in an instant. The thermal inertia of a transistor is smaller than that of a fused fuse, so the latter cannot be used to protect the former. The series regulator must be protected by an electronic protection circuit with fast response. The electronic protection circuit can be divided into current limiting type and current cutoff type. The former limits the current of the regulating tube below a certain safety value, while the latter immediately cuts off the current of the regulating tube in case of overload or short circuit accident at the output end.


The regulated DC power adapter will produce a strong negative high voltage, and then connect one section to the cathode and the other section to the anode, and then generate a strong electric field between the cathode and the anode. After the electric field at both poles exceeds the specified intensity, it will discharge. At this time, ionization will occur around the electric field, and then a large number of electrons and ions will be produced. After a while, you can hear strong electromagnetic wind around the electric field. When the light is dim, you can see the faint violet corona around you. Moreover, around the electric field, there will be a lot of tar, dust and other particles combined with ions or electrons, which will move to the poles under the action of the electric field force. The mass of electron is very small, but its motion speed is very fast, so it is mainly carried out by charged particles.

Post time: Mar-30-2022