2. Select the rated voltage of the windproof fuse according to the line voltage.
3. Select the rated current of the windproof fuse according to the load characteristics.
4. The selection of melts at each level must cooperate with each other. The latter level is smaller than the previous level. The currents on the main gate and each branch line are different, and the selection of fuses is also different. If there is a short circuit in the line, the 15 A and 25 A fuses will blow out at the same time, and the protection characteristics will lose selectivity. Therefore, only if the main gate and branches maintain a 2-3 level difference, this kind of phenomenon will not occur. For example. The low-voltage side outlet of a transformer is RT0 1000 / 800, and the motor is RT0 400 / 250 or RT0 400 / 350. The ratio of the rated current between the upper and lower stages is 3.2 and 2.3 respectively. Therefore, the selectivity is good, that is, if the branch circuit is short-circuited, the branch circuit is insured. The fuse does not affect the power supply of the main gate.
5. The melt cannot be chosen too small. If the selection is too small, it is easy for one phase fuse to blow out, causing the motor to run in a single phase and burn out; according to statistics, 60% of burned out motors are caused by improper fuse configuration.
