Working principle

As an overcurrent protection component, traditional fuse only protect one time and need to replace another once burned. The resettable fuse, one newly overcurrent protection component, has overcurrent protection and auto recoverable. Overcurrent protection:PpTC component is at the low resistance state to ensure the circuit work normally. When encountered short circuit or high current, PpTC component can heat by itself to improve resistance with limiting small enough current to protect circuit. Automatic resettable:PpTC component can recover to the low resistance state after stopping ovel current. That not only can avoid replacing the burned one, but also avoid keeping circular on-off state where it occurs damage in circuit, PpTc resettable fuse has double functions that are overcurrent protection and automatic recovery because of structurde materials. It is made of high polymer mixed with conductinc material. Normally, the conducting material can form three-dimensional conducting channel with high polymer to enable PPTC resistance to low. When high current passes though the circuit suddenly, PPTC component temperature rises rapidly and high polymer expands rapidly to cut off the conducting channel to rise rapidly the resistance. It achieves protection the circuit by reducing the current like the circuit cuts off After high current disappears, PpTC self-heating can't keep high resistance and recovery the lowest resistance state. Compared with traditional fuse, PpTC has recoverable ,small size and durable structure.

Movement principle

PPTC resettable fuse movement principle is an energy homeostasis. The current flowing through the PPTC element brings amount of the heat because of PpTc. All or part of the heat generate by distributing to the environment.The heat that doesn't dissipate will improve the temperature of PpTC component. The thermal heat generation and dissemination of balance when the normal working time is low. PpTC does not move in the low resistance while the current or environmental temperature increase, provided that generating heat and distributing heat are in balance, PPTC still doesn't move. When the current or the environment temperature increases again, PPTC will reach higher temperature. If the current or the environment temperature continues increasing, the generated heat wil be greater than the dissipated heat, making the PpTC component temperature increases rapidly. Small changes in temperature cause substantial increase in resistance at this stage,then PPTC component is in the high resistance state protection. An increasing anti-resistance limits the current to make it drops sharply in a short period of time. Finally, circuit equipment can be protected from being damaged. As long as the applied voltage generates enough heat for the heat that PPTC component dissipate, it can keep movement station (high resistant) under a state of change. While the applied voltage disappears, PPTC can automatic recovery.

Environmenttemperature effective

The current is on the decrease by resettable fuse when environment temperature is higher than 25°C The current can 100% recover by resettable fuse when the operating temperature is 20'c in the circuit. if more than two time current occurs, the recoverable fuse can work, The higher environment temperature and current passe through, the shorter the working time is. The changeable between environment temperature and current as follows:

Classification

Keeping Current(lH): The highest current when don't touch PPTC resettable fuse under 25 'C quiescent environment Touching CurrentL(lT): The lowest current when PPTC resettable fuse resistance becomes the lowest one to the highest one under 25'Cquiescent environment. Max Voltage(V max): PPTC resettable fuse can undertake max working voltage. Max Current(l max): P 35 PPTC resettable fuse can undertake max current Movement time (T trip): The max movement tine under the specified current Movement Power (Pd typ): Dissipation power when PPTC resettable fuse is in movement state under 25'Cenvironment Min Resistance (R min): The min zero power resistance under 25 °Cenvironment Max Resistance: The max zero power resistance under 25 'Cenvironment