Products > Thermistor > Over current PTC thermistor

Over current PTC thermistor

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feature
1
、high voltage endurance
2
、good impact endurance
3
、long life span
4
、small residual current
5
、low power
6
、good flame-resisting
7
、safe and reliable

application range
appliance
refrigerator,air conditioner
motor
hothouse of train
dryer
others

 

description
MZ62 series PTC thermistor is a self-protective,automatic recovery component for abnormaltemp. and current,is commonly called "self-recovery fuse""ten thousand fuse".It is instead of traditional fuse,widely used in over current protection for motors,transformer,and electronic circuit.PTC thermistor can limit the whole line dissipation to reduce the residual current by its resistor value changes abruptly.PTC can recover its protect function after removing the failure.But in traditional fuse circuit ,fuse can't recover after break
。

To choose PTC as over load protect component,firstly to confirm the max normal line working current or PTC's hold currentand PTC's fix placenormal working the max ambient temperature、secondly is the protective currentor PTC's trip current )、the max working voltage、rated zero power resistance,to consider the component's size at the same time。 as following diagram:the relation of operating environmenttemp.,the hold current,and the trip current。


principle
PTC's current is smaller than the rated current
,PTC resistance value is in normal condition,the value is very small,it can't affect the normal working of the protect circuit。when the circuit is in failure,the current exceed the rated current greatly,PTC heat up abruptly,get into high value state,let the circuit in "off" state,so as to protect the circuit .After the failure is removed ,PTC's value recover to low resistance,the circuit recover to its normal condition。

Figure 2 is V-A curve  and load curve in normal working
,from point A to B,PTC's voltage raised step by step ,PTC's current also linear increasing ,that is PTC's value don't change mainly,or it is in low resistance state;From point B to E,the voltage raised step by step,as PTC is hot,  its resisort value increased abruptly,PTC's current lowed rapidly,that  PTC  is in protect state。The normal load curve is lower than point B,PTC isn't in protect state。

There is 3 typies of overcurrent protect commonly


1
、over currentfigure 3):RL1 is load curve in normal working,when reducing the load resistance,such as the transformer circuit is short,the load curve changed from RL1to RL2,exceed point B, PTC get into protect state;

2
、over voltagefigure 4):the power voltage increase ,such as from 220V to 380V suddenly,the load curve changed from RL1to RL2,exceed point B, PTC get into protect state;

3
、over heatfigure 5):when the ambient temp. raised to a certain limit,PTC's V-A property curve is changed from A-B-E to A-B1-F,load curve RL exceed point B1,PTC get into protect state;

 

application

 

product list

The electronic parameter and size above only for reference,according to custo

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