There are many ways to suppress the surge current. In general, the resistance current limiting method is used to suppress the surge current in the small and medium power supply.Let’s examine how to use NTC thermistors for surge current suppression.
NTC thermistors, also known as negative temperature coefficient thermistors, are characterized by a non-linear decline in the resistance value as the temperature increases.NTC is generally divided into temperature measuring thermistor and power type thermistor in application. NTC thermistor used to suppress surge refers to power type thermistor.
At room temperature, NTC thermistor has a higher resistance value, namely the nominal zero power resistance value.Such as 10 Ω concatenated NTC, boot surge current for： I = 220 x 1.414 / (1 + 1) = 28 (A), more than 311 A not when using the NTC thermistor reduced 10 times, effectively play the role of the inhibition of surge current.
Boot after, because of the NTC thermistor fever, temperature rise rapidly, its resistance would be in the millisecond time drops rapidly to the level of a small, usually only a fraction of the size of Europe to several European, compared with the traditional fixed resistance current limiting resistor, which means that the resistance on the power consumption for falling resistance decreases the scores to one hundred times, so the design is very suitable for have higher request for conversion efficiency and energy saving products, such as switching power supply.
After power failure, NTC thermistor with its own cooling, the resistance value will gradually restore to the nominal zero power resistance value, the recovery time needs tens of seconds to a few minutes.The next time you start, repeat the above process.
Post time: Oct-26-2021