The power adapter burned varistor often happened because _

Power adapter varistor often burned for 425-2020 10 - 28 10:00:48 power adapter varistor the resistance of the material is a semiconductor, so also is a kind of semiconductor resistor. Now commonly used are zinc oxide varistor. Power adapter pressure sensitive resistance in the circuit is simple generalization has three functions: a overvoltage protection; Two lightning resistance requirements; Three safety testing needs. Power adapter varistor is not perceived stress, is a voltage sensor, a bit like a fuse, more than itself on the voltage will be breakdown, open circuit protection. Power adapter in the varistor used for over-voltage protection system, but its flow capacity is big, but are less energy capacity, in addition it the impact of the current pulse width is far less than the actual width of pulse current, large and medium-sized power semiconductor system, so frequent short circuit. Power adapter in the varistor often burned reasons: 1, aging, characterized by increased leakage current, pressure-sensitive voltage dropped significantly, until to zero; Aging failure refers to the low resistance linearization resistor body gradually intensified, malignant increased leakage current and concentration into the weak spot, weakness in the material to melt, hole formed around 1 k Ω short circuit, power supply continue to push into a larger current short-circuit point, form a high fever and burst into flames. This accident can usually with a pressure sensitive resistance in series of hot melt contact to avoid. And transient overvoltage destruction is refers to the strong transient overvoltage resistance body perforation, the result of the more current and high fever on fire. The whole process in a relatively short period of time, so that body set on thermal contact resistance to fuse. 2, the transient overvoltage. The number of 3, over voltage protection; Around 4, working temperature; 5, varistor presence of squeezed; 6, whether through the quality certification; 7, the surge of energy is too big, beyond the absorbed power; 8, pressure is not enough; 9, and surge current is too large, and so on. The use of the power adapter in the varistor security has always been a need to attach importance to the problem. By piezoresistor widely used in home appliances and other electronic products, overvoltage protection and lightning protection, inhibiting surge current, absorption peak pulse, clipping, high voltage arcing, de-noising, protection of semiconductor components, etc. Advice to choose high quality pressure sensitive resistor. Power adapter in the varistor, piezoresistor power adapter varistor often burned aging failure reasons; The transient overvoltage destruction; The number of over-voltage protection; Whether through quality certification; Pressure is not enough; Excessive current and surge, etc. , the power adapter piezoresistor widely used in electronics, the overvoltage protection; Lightning protection; Inhibition of surge current; Absorption peak pulse; Limiting; High voltage arcing; De-noising, protect semiconductor components, etc.