Fuse is required to select the fuse, protection circuit line according to the load
First, the operating fuse damage, replacement to follow the following principles.
1. The cause must be identified and processed before replacement. Contact with the place fused – contact false. (The first two kinds of failure to find the cause, remove before replacing the fuse; contact false should be removed from the oxide and melting layer, the deformation is not serious should be restored, etc., to ensure good contact before replacing the fuse). 2, the original demolition of the original. a. Rated voltage, rated current, type, material, and other rated parameters can not be changed. b. Gaskets, retaining rings, padding, and other accessories can not be changed, damaged to make up. c. The fuse can not (The first two kinds of failure to find the cause, remove before replacing the fuse; contact false should be removed from the oxide and melting layer, the deformation is not serious should be restored, etc., to ensure good contact before replacing the fuse).
2. the original demolition of the original. a. Rated voltage, rated current, type, material, and other rated parameters can not be changed. b. Gaskets, retaining rings, gaskets, and other accessories can not be changed, damaged to make up. c. The fuse can not touch the fuse shell. d. The rated current of the fuse must be less than or equal to the rated current of the fuse.
Second, the equipment selection fuse and select the fuse according to the load should be in accordance with the following methods.
1. according to the system voltage and installation location to choose the fuse model. When the high-voltage power supply system is installed outdoors, select a high-voltage drop fuse. When the high-voltage power supply system is installed indoors, choose high-voltage plug-in porcelain sand-filled fuse (quartz sand interrupter). A low-voltage power supply system selects a porcelain fuse (plug or spiral type) in line with the system voltage or selects an RM-type fuse in line with the system voltage. Electronic circuits or control circuits generally choose quick-break insurance (we often say the glass tube insurance). The rated voltage of the fuse is greater than or equal to the rated voltage of the system.
2. the fuse rated current calculation: fuse material and model according to the fuse model selection, rated current calculation according to the type of load for calculation.
(1) load for the resistance class load, such as incandescent lamps, electric heating equipment, etc.: a. Line trunk fuse rated current is equal to 0.9-1 time the rated current of the meter. b. Branch fuse rated current is equal to 1-1.1 times the sum of the rated current of the load.
(2) In the protection circuit line, The load is motor type load: a. Single motor, the melting current is equal to 1.5-2.5 times the rated current of the motor. b. Multiple motors, the melt rated current is equal to 1.5-2.5 times the rated current of the largest motor in the load and the sum of the rated currents of other motors.
(3) load for welding machine type load can take 1.3-1.5 times the rated current according to the frequency of use. If you only know the power, 220 volts take 6 times the number of kilowatts, 380 volts take 4 times the number of kilowatts.
