What is a glass fuse?
Glass tube fuse is a kind of safety tube, which is mainly a safety device to protect the safety of the whole circuit board and circuit by fusing its own fuse when the circuit is abnormal (abnormal rise in current, temperature, withstand voltage, etc.). The following explains the product definition of safety tube, parameters of safety tube and precautions related to type selection.
Safety tube structure and material composition of glass tube:
1. Welding material: Tin
2. Copper cap: nickel plated copper
3. Body: glass tube
4. Fuse: alloy wire
Classification of glass tube and safety tube:
First, according to the installation form, it can be divided into two types: with lead and without lead.
Glass Cartridge Fuse without lead wire needs to be used together with the supporting fuse holder. The advantage of this kind of product is that when the fuse tube is damaged and the fault is eliminated, the fuse tube only needs to be reinstalled into the fuse holder, which is very convenient to replace. The disadvantage is that it needs one more process during production, and the fuse tube needs to be installed after welding the fuse holder, Therefore, in the case of the same specification, the cost of fuse without lead is slightly higher than that with lead for the first production.
The early production cost of lead wire is low, only one process is required and the cost of one fuse holder is reduced. However, when the Glass Body Fuse is damaged, it needs to be replaced by professionals after disassembly, and the replacement cost is very high.
Second, the fusing speed can be divided into several types according to the fusing speed: extra slow break (TT), slow break (T), medium speed (m), fast break (f) and extra fast break (FF). See I in the specification here ² t。
Third, breaking capacity, high breaking (H) and low breaking (L).
Fourth, according to the size, it can be divided into 3.6 * 10, 4.6 * 16, 5 * 20, 6.3 * 30, etc. the specific size depends on each factory. These types of sizes are those with more consumption.
Fifth: according to the classification of safety specification certification, European regulations, Japanese regulations and American regulations.
Safety tube identification:
Trademark: + product name + Certification number
Specification: - A-V / - ma-v
Trademark: FBelec
Specification: 3.15a 250V
Related Description: edit broadcast
1. Rated voltage of agc glass tube fuse
The rated voltage of the Auto Fuse Assortment is the maximum working voltage under the normal working state of the Glass Fuses 30mm Fast Blow Tube.
The fuse can only be used in circuits less than or equal to the service voltage, that is, the working voltage of the selected fuse must be greater than the normal voltage in the circuit. For example, 3a125v fuse can never be used in 250V withstand voltage circuit, but can be used in 125V and below circuits.
2. Calculate the rated current of fuse in
Rated current in = IRM / (SC * TC)
In represents the rated current of replacement glass tube fuses
IRM represents the maximum operating current in the circuit
TC represents the temperature decay rate (refer to the temperature curve)
The safety attenuation rate of American regulations is: SC -- 0.75
The safety attenuation rate of European regulations is: SC -- 0.9
The safety attenuation rate of the daily gauge is: SC -- 0.85
Main: the calculated in is the minimum rated current of the selected fuse, and the best rated current equal to or greater than in shall be selected.
3. Ambient temperature
Under the ambient temperature of 25 ± 5 ℃ at room temperature, the rated current of the fuse is not affected by the temperature. When the ambient temperature rises continuously, the rated current attenuation of the fuse will be greater when it works for a long time. When selecting the fuse tube, the influence of ambient temperature change on the fuse tube must be considered.
The increase or decrease of temperature will accelerate the fuse reaction and slow down the cargo. The curve is obtained through a large number of experiments.
4. Consider current pulse
Current pulse: including power on moment, voltage change and all other transient process pulses. The current pulse in the circuit can be measured by oscilloscope.
If the fuse is required to withstand the transient pulse generated under normal conditions (such as startup and shutdown) without fusing, the ability of the fuse to withstand the pulse shall be considered, and the slow break series will generally be selected.
Note: when selecting the fuse, the I of the surge is calculated according to the surge waveform generated in the actual circuit ² T value, and then use the "pulse cycle capacity" curve and the rated fusing thermal energy value of fuse tube (rated I of fuse tube ² T value), and finally the impact resistance times of the safety tube under this sudden wave can be calculated.
5. Pulse current in circuit I ² T value.
According to the relevant waveform and calculation formula, I is approximately calculated ² T value (WP).
6. Current pulse withstand times
U = WP / WR, using pulse I in the circuit ² The value of T (WP) is divided by the rated fusing value (WR) of the fuse. According to the percentage of u and Figure 4, it can be seen that:
When u = 22%, it can withstand 100000 pulses
When u = 29%, it can withstand 10000 pulses
When u = 38%, it can withstand 1000 pulses
When u = 48%, it can withstand 100 pulses
7. Select rated current of fuse tube:
Safety regulation attenuation coefficient
Temperature attenuation coefficient
Withstand pulse current and impact times (I) ² T value and fuse rating I ² T value comparison)
8. Routine testing of fuses
A. Overload test
Bã€I ² T test
C. Breaking capacity test
D. Insulation resistance test
E. Voltage drop test
F. Durability test
G. Temperature rise test
H. Failure test
9. Market demand for insurance management industry
A. Miniaturization: power adapter, charger, LED driver, etc. the demand for miniaturization of terminal products is mainly 2010 plastic square or 3 * 7mm.
B. High short circuit: the short circuit capacity of conventional fuse is below 130a250v, and the actual input short circuit current is about 150-250a.
C. Safety: the use of small-size fuse tubes for low power is increasing, but the phenomena of sound, light and smoke during short circuit can not be completely avoided.
D. SMD chip type: the requirements of miniaturization and automation parts of terminal products, but the SMD characteristics can not be met.
NINGBO FBELE ELECTRONICS CO.,LTD.
FBELE company was founded in 1997, is China's leading manufacturer of acoustic and other electronic components, we designs,manufactures, distributes high quality products in very competitive price, bestservice, timely delivery, small order acceptable, etc. Our products include piezo ceramic element, piezoelectric buzzer, magnetic buzzer,speakers, transducer, receiver, electret condenser microphone, magnetic contact. Piezoelectric alarm,ultrasonic sensor,PZT ceramics,etc.
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