Ceramic Cartridge Fuse
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Fuse is the circuit, electrical equipment short circuit and overload protection of electrical appliances. Fuse is generally connected in series in the circuit when the circuit works normally, the fuse is equivalent to a wire; when the circuit is short-circuit or overload, the current flowing through the fuse is very high, the fuse will open the circuit, so as to protect the circuit and electrical equipment.
There are many types of fuses, the common ones are RC insert fuse, RL spiral fuse, RM closed fuse without packing, Rs fast fuse, RT packed tube fuse and RZ self-repeating fuse, etc. The model meanings of fuses are described as follows.
Common classification of fuses.
1、RC plug-in fuse
RC plug-in fuse is mainly used in circuits with voltage at 380V and below and current at 5~200A, such as lighting circuits and small capacity motor circuits. Figure 2 shows a common RC plug-in fuse. When this fuse is used in the circuit with rated current below 30A, the fuse generally uses lead-tin wire; when used in the circuit with current of 30~100A, the fuse generally uses copper wire; when used in the circuit with current above 100A, the fuse is generally made of copper with variable cross section.
Figure II a common RC plug-in fuse
2、 RL spiral fuse
Figure 3 shows a common RL spiral fuse, this fuse in use, to install a spiral fuse tube inside, in the installation of the fuse tube, first the fuse porcelain cap screwed down, and then the fuse tube into the internal, and then screw the porcelain cap.
The upper and lower part of the fuse tube is a metal cover, and the inside of the fuse tube is equipped with quartz sand and fuse wire. There is a red fuse indicator in the center of the metal cover above the fuse tube, and when the fuse wire is fused, the color of the indicator will change to indicate that the internal fuse wire has been broken. The color change of the indicator can be observed through the fuse porcelain cap on the glass window.
Figure 3 RL spiral fuse
RL spiral fuse has the advantages of small size, strong breaking capacity, safe and reliable work, easy installation, etc. It is usually used in the distribution box, control box and control circuit of machine tool motor below 200A in factories.
3、RM no packing closed fuse
Figure 4 shows a typical RM no packing closed fuse, it can be removed. This fuse is a variable-section zinc fuse, which is installed in the fiber tube, zinc blade ends of the knife contact through the brass cap, and then through the gasket inserted in the knife seat. When this fuse passes a high current, the narrow part of the zinc sheet fuses first, leaving the middle large section of the zinc sheet disconnected to form a large interval, thus facilitating arc extinguishing.
RM no packing closed fuse has the advantages of good protection, strong breaking capacity, easy replacement of the fuse and safety and reliability, etc. It is mainly used in the power circuit below 380V AC, below 440V DC and below 600A current.
Figure 4 RM without packing closed fuse
4、RS fast fuse with packing
RS fast fuse with filler is mainly used for silicon rectifier devices, thyristor devices and other semiconductor devices and their supporting equipment short-circuit and overload protection, its fuse is generally made of silver, with the advantages of rapid fusing, can interrupt the arc. Figure 5 shows two common RS fast fuse with filler.
Figure 5 common RS with packing fast fuse
5、 RT has the packing closed tube fuse
RT packed tube fuse, also known as quartz fuse, it is often used for overload and short circuit protection of electrical equipment such as transformers and motors. Figure VI (a) shows a few common RT packed closed tube fuse, this fuse can be connected to the circuit with screws, clips, etc.; Figure VI (b) shows a fuse inserted in the case of the clips.
Figure 6 (a) Several common RT packed closed tube fuses
Figure 6 (b)
RT packed enclosed tube fuse has the advantages of good protection, strong breaking capacity, good interrupting performance and safety in use, mainly used in the short-circuit current of the power grid and distribution equipment.
The fuse detection
Fuse common fault is open circuit and poor contact. There are many types of fuses, but the detection method is basically the same. The following is an example of the detection of the fuse shown in the figure to illustrate the detection method of the fuse. Detection, the multimeter block switch select 200Ω block, and then the red and black pens are connected to the two ends of the fuse, measure the resistance of the fuse. If the fuse is normal, the resistance is close to 09; if the display shows beyond the range symbol “1” or oL” (pointer multimeter shows infinite resistance, it indicates that the fuse is open; if the resistance is unstable (sometimes large and sometimes small, it indicates that the fuse internal contact is poor.
