Selection technique of patch self recovery fuse:
According to the maximum working voltage of the line V, the normal operating current I, fault current If and the maximum use of ambient temperature TM to select the appropriate model. In the maximum use of ambient temperature TM, should be satisfied:
(IH) (TM) is slightly larger than I
The IT (TM) = If = Imax
The Vmax = V
Here the line voltage, current is the DC or AC RMS value.
Self recovery fuses are generally used in series with the front end of the circuit to be protected. Used in place of the current fuse can avoid the trouble of frequent replacement.
The role of chip fuse
The chip fuse is a kind of self recovery fuse, the product material, function, characteristics and working principle is also the same as self recovery fuse. Self recovery fuse (PPTC: polymer self recovery fuse) is a kind of positive temperature coefficient polymer thermistor, made over current protection, can replace the current fuse. PPTC self recovery fuse action principle is a kind of energy homeostasis, current flow of PPTC components due to the relationship between PPTC generate heat, heat generated by all or part of the emitted to the environment, and not dissipate heat will raise the temperature of PPTC components. The normal work of the circuit in its resistance is very small (pressure drop is very small), when the circuit overcurrent resulting in the increase of the temperature, the resistance increased sharply with the increase of several orders of magnitude, circuit current is reduced to below the safety value, so that the back of the circuit to be protected, disappearance of the overcurrent automatic recovery for low resistance. When the trouble is eliminated, the PPTC element is cooled quickly and will revert back to the original low resistance, so that it can be re worked as a new PPTC element.