At present, everyone is very interested in current-limiting fuses. Everyone wants to know about current-limiting fuses. Then Zhiguang fuse manufacturers have collected some information about current-limiting fuses to share with Everyone, I hope I can help you.
What is a current limiting fuse?
Current-limiting fuses are generally quartz sand fuses that use quartz sand as the filler of the fuse and are closed fuses that have the ability to limit short-circuit currents and can quickly cut off fault currents. Current limiting fuses are divided into resistance current limiting and arc reactance transformation current limiting. Resistor current limiting makes the current value in the circuit limited below a certain amplitude. Regardless of short circuit or not, it will not exceed a certain value. Current-limiting fuses have two melt structures, an in-line melt, and a spiral wound melt. The arc reactance increases with the elongation of the arc after the arc initiation of the in-line melt. And gradually change the phase. Spiral melts use spiral reactance transformation to change phase. The two create zero rest so that the voltage and current cross zero at the same time. Phase shifting extinguishes the arc before the current reaches its peak value. The current limiting ability of this kind of arc extinguishing is very different. It can be seen that the type and structure of the current-limiting fuse must be considered in the power supply design. A fuse that can limit the peak value of the short-circuit current is called a current-limiting fuse.
What is a non-current-limiting fuse, the difference between a current-limiting fuse and a non-current-limiting fuse
The main difference between a current-limiting fuse and a non-current-limiting fuse is that the latter fuses quickly, and it is blown before the short-circuit current rises to the maximum value within a waveform. The current-limiting fuse requires extremely fast fusing when the fault current flows, so as to achieve the purpose of limiting the short-circuit current. Therefore, there are some high-speed fusing metals in the middle of the fuse, and its resistance is relatively large, and the measured resistance of the fuse is also large. Non-current-limiting fuses do not have this requirement.
A fuse that cannot safely cut off the fault current within a limited time is called a non-current-limiting fuse, which is suitable for general occasions.
Is the fuse current limiting?
The function of the fuse is mainly to protect the circuit and equipment from short circuits, and some fuses also have the function of overload protection.
A current-limiting fuse refers to a fuse that can safely cut off all possible currents within its rated current and current-limiting range. It limits the fusing time at the rated voltage to be equal to or less than the period of the first main wave or symmetrical current wave, and at the same time limits the passing current to less than the peak current.
How Current Limiting Fuses Work
The principle of the fuse is to use the thermal effect of the current. When the current exceeds the set current, the conductor inside the fuse is overheated and blown to achieve the purpose of cutting off the circuit. A fuse is a wire or several wires connected in parallel and installed in a closed space. The cross-sectional area of this space can be circular or square. The lead wire of the fuse is located in the center of this closed space, and the surrounding is filled with quartz sand-dissipating heat evenly and ensuring that the fuse will not blow under normal conditions.
Main parameters and characteristics of high voltage current limiting fuse:
(1) Rated voltage: refers to the long-term withstand voltage of the high-voltage current-limiting fuse after it is broken, generally equal to or greater than the rated voltage of the equipment or line.
(2) Rated current: The rated current of the fuse and melt refers to the current passing through for a long time. Generally, it is about 1.5~3 times the rated current of the equipment.
(3) Rated breaking capacity: refers to the ability to reliably break overload or short-circuit current under fault conditions. Generally expressed by breaking current or breaking capacity.
(4) Insulation level: generally expressed by power frequency withstand voltage and lightning impulse withstand voltage.
(5) Ampere-second characteristic: refers to the relationship between the action time of the high-voltage current-limiting fuse and the current passing through the fuse