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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 componentfirstly to confirm the max normal line working current or PTC's hold currentand PTC's fix placenormal working the max ambient temperaturesecondly is the protective currentor PTC's trip current )、the max working voltagerated zero power resistanceto 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 conditionthe value is very smallit can't affect the normal working of the protect circuitwhen the circuit is in failurethe current exceed the rated current greatlyPTC heat up abruptlyget into high value statelet the circuit in "off" stateso 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 mainlyor it is in low resistance stateFrom point B to Ethe voltage raised step by stepas PTC is hot,  its resisort value increased abruptlyPTC's current lowed rapidlythat  PTC  is in protect stateThe normal load curve is lower than point BPTC isn't in protect state

There is 3 typies of overcurrent protect commonly


1
over currentfigure 3):RL1 is load curve in normal workingwhen reducing the load resistancesuch as the transformer circuit is shortthe load curve changed from RL1to RL2exceed point B PTC get into protect state

2
over voltagefigure 4):the power voltage increase such as from 220V to 380V suddenlythe load curve changed from RL1to RL2exceed point B PTC get into protect state

3
over heatfigure 5):when the ambient temp. raised to a certain limitPTC's V-A property curve is changed from A-B-E to A-B1-Fload curve RL exceed point B1PTC get into protect state

 

application

 

product list

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

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