How to choose a good fuse
(1)UN fuse≥UN line.
(2)IN fuse ≥ IN line.
(3) The maximum breaking capacity of the fuse should be greater than the maximum short-circuit current on the protected line.
Fuse selection
(1) Selection of fuse type
The type of fuse should be selected according to the use occasion. Grid power distribution generally uses knife-type contact fuses (such as HDLRT0RT36 series); motor protection generally uses screw-type fuses; lighting circuits generally use cylindrical hat-shaped fuses; to protect silicon-controlled components, quick-acting fuses for semiconductor protection should be selected.
(2) Selection of fuse specifications
1. Selection of melt rated current
(1) For loads such as transformers, electric furnaces and lighting, the rated current of the European cable joint melt should be slightly greater than or equal to the load current.
(2) For power transmission and distribution lines, the rated current of the melt should be slightly greater than or equal to the safe current of the line.
(3) When used as short-circuit protection in a motor circuit, the starting conditions of the motor should be considered, and the rated current of the melt should be selected according to the length of the motor starting time.
For motors whose starting time is not long, the rated current of the melt can be determined by the following formula IN melt = Ist/(2.5~3)
In the formula, Ist——the starting current of the motor, unit: A
For motors with long starting times or frequent starts, determine the rated current of the melt according to the following formula: European cable joint
IN melt=Ist/(1.6~2)
The rated current of the fuse at the main busbar that supplies power to multiple motors can be calculated as follows:
In=(2.0~2.5)Imemax+∑Ime
Note: The rated current of the In fuse; the rated current of the Ime motor; the rated current of the motor with the largest capacity among the Imemax motors; ∑ the sum of the rated currents of the remaining Ime motors.
Yichang Hengyuan Technology Co., Ltd. specializes in the production of European-style cable joints, plug-and-pull heads, cable branch boxes, American-style elbow joints, high-voltage vacuum circuit breakers, high-voltage load switches, arresters, zinc oxide arresters, tank arresters, over-voltage protectors, counters, monitors, heat-shrinkable cable accessories, Manufacturer of cold shrink cable accessories, T-heads, wall bushings, European cable accessories, American cable joints, transformer neutral point protection devices, fuses, isolating switches, PT cable heads, elbow cable joints, 10kV outdoor terminals, switch cabinets, cable intermediate joints, cable accessories and other products
