company news about How to select the fuse of appropriate specification for the protection of PV battery string

        The North American standard NASI/NFPA 70 has clearly stipulated that the protective appliances on the DC side require DC specifications. For the fuse protecting the PV string, the rated current In>=1.56Isc (Isc is the short circuit current of the PV string) is required, and the rated voltage is not less than the open circuit voltage Voc at the local minimum temperature of the PV string, and the correction factor is provided to calculate the actual use temperature Voc; For the fuse protecting the PV array, it is required to limit the current I<=In<1.56Isc by 1.25, and the wire specification at this position should not be less than 1.56Isc, so it is appropriate to take the maximum rated current in the series specification below the calculated value of current 1.56Isc.

        The agreed fusing current of DC PV fuse in IEC system is 1.45 In, and the agreed fusing current of DC PV fuse corresponding to American Subject 2529 technical specification is 1.35 In, that is, the actual carrying capacity of DC PV fuse in IEC system is about 1.1-1.2 times of that of American Subject 2529 fuse. Therefore, considering the difference of actual carrying capacity, the fuse for protecting PV battery string should be revised to In>=1.42Is by referring to the above formula In>=1.56Isc. Therefore, calculate the fuse specification value In according to the modified formula, and take the fuse link with the current level greater than the calculated value and closest to the calculated value. In addition, the wire specification should not be less than Is, preferably greater than 1.25 Is; In the same way, the fuse protecting PV array should be corrected to In<1.42Is by referring to the above formula In<1.56Isc, and the maximum rated current specification in the serialized specifications below the calculated value of current 1.42Isc should be taken. When the temperature around the fuse is high, if it is higher than 45 or multiple fuses are installed close to the ground in the combiner box, the capacity shall be reduced, and the capacity shall be reduced as recommended by the fuse manufacturer.