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Electrical & Electronics >> drop out fuse

 Hont is a professional Drop out fuse manufacturer in China. We are taking wenzhou as the researching and development manufacturing base, and China Electrical Appliance City, Liushi ,as the main sales center. Now it has become a diversified enterprise, integrating research and development, production, sales and service together. The company's products cover high-voltage electrical appliances, power transmission and distribution equipment, construction industry and electrical automation industries. Our main products include fuse, high arrester, insulator, high voltage vacuum circuit breaker, mutual inductor, etc. The company has a strong technical force, superb production technology, advanced testing equipment, perfect scientific management system, the enterprise has passed ISO9001:2000 international quality system certification. Hont electric always carries out the business philosophy of "Integrity management, Quality win; Focus on development and keep innovating.". We are keeping comprehensive development, pursuit of excellence. We spare no effort in the new product development, product quality improvement, service quality improvement, human resources input, and we are forging ahead! The company always closely combines its own interests with the needs of the society, and strives to achieve the mission of "Sustainable supply safe, energy-saving, controllable and efficient products for the power system". In the increasingly fierce market competition, Hont's brand awareness, reputation and market share, is in China's high-voltage power system field increasingly leading position. And we have received the majority of users unanimously praise over years!
 
Drop out fuse manufacturer
 
Brief introduction:
Drop out fuse is a short circuit protection switch. It is characterized with the features of economy, convenient operation and strong adaptability to outdoor environment. Drop out switch is widely used in 10kV/12KV distribution line and one side of distribution transformer for protection and equipment operation. Drop out fuse is outdoor high - voltage protective equipment. It is installed on the high-voltage side of distribution transformer or the distribution wiring branch, used as the short circuit of transformer and line, overload protection and sub - and combined load current. The drop out fuse is composed of two parts: the insulating bracket and the fuse tube. The static contact is installed at both ends of the insulating bracket and the moving contact is installed at both ends of the fuse tube.The fuse tube consists of an inner extinguishing arc tube and an outer phenolic straight tube or epoxy glass tube.

Drop out fuse manufacturer
 
In normal operation of drop out fuse, the fuse tube will turn to be closed with the tension of the fuse. When the power system fails, the wrong current results in the fuse fusing quickly and forming an electric arc. The extinguishing arc tube is heated by the electric arc, and will decompose a large amount of gas, which causes high pressure in the tube. And these air in the tube will blow along the pipe in vertical direction. The arc is quickly stretched and extinguished. After the fuse is blown, the lower static contact loses tension and turns down, so that the tightening mechanism releases the fuse tube.Then the fuse tube falls to an obvious breaking position. When it is necessary to pull the load, pull the active contact with the insulator. And at this time, the active and static contact still keep contacting state. Continue to pull the contact with the insulator, the auxiliary contact will also separate, and an electric arc is generated between the heads. The electric arc will be stretched in the gap of arc chute. And the arc chute will produce gas. After the current turns to be zero, then the it will extinguish the electric arc.
 
Working principle:
 
The moving contacts at both ends of the fuse are tightly tied by the fuse, and the upper moving contacts are pushed into the protruding part of the "duck mouth". And the upper static contact made of phosphorous copper sheet is attached to the top moving contact, so the fuse tube is firmly stuck in the "duck mouth". When the short circuit current is blown through the fuse, an arc is generated. Under the action of the arc, the steel paper tube lined with the inner side of the fuse tube generates a large amount of gas. And because the upper end of the fuse tube is sealed, and the gas is ejected to the lower end, to blow out the arc. The upper and lower moving contacts of the fuse lose the binding force of the fuse, due to the breaking of the fuse. Under the action of the gravity of the fuse tube and the function of the upper and lower static contacts, the fuse quickly drops off, disconnecting the circuit, which cuts out the fault line or fault equipment.
 
One of the reasons why the fuses on the actual 10kV line system and distribution transformer cannot operate correctly is that the electrician has poor quality and weak sense of responsibility. These electician seldomly do the  maintenance and check the drop out fuse in a long period. The second reason is that the product quality of the drop out fuse is inferior and cannot be drawn and operated flexibly. Both two reasons reduce the function and efficiency of drop out fuse. In reality, there is often a lack of fuse pipe, fuse body. People will use copper wire, aluminum wire or even iron wire hook to replace the fuse, which lead to the high tripping switch rate of the power system and high fault rate of distribution transformer.
 
 
 Main functions:
The drop out fuse is installed on the branch line of 10kV distribution line, which can reduce the range of power failure range. Because it has an obvious disconnection point and has the function of isolating switch, which creates a safe operating environment for the line and equipment in the maintenance section and increases the safety of maintenance personnel. Installed on the distribution transformer, it can be used as the main protection of the distribution transformer. Therefore, it is popularized in the distribution line of 10kV and distribution transformer.
 
 
 
Applicable environment:
 
10 kv drop out fuse is suitable for the air without conductive dust, corrosive gases and flammable, explosive and dangerous environment, and places where the annual temperature change is higher than outdoor places within + 40 ℃ as well. The selection is made according to the parameters of rated voltage and rated current, that is, the rated voltage of the fuse must match the rated voltage of the protected device (line). The rated current of the fuse shall be greater than or equal to the rated current of the fuse. The rated current of the melt can be selected as 1.5 ~ 2 times of the rated load current. In addition, the selected fuse shall be checked according to the three-phase short circuit capacity of the protected system. You should ensure that the three-phase short-circuit capacity of the protected system is less than the upper limit of the rated disconnection capacity of the fuse, but it must be greater than the lower limit of the rated disconnection capacity. If the rated disconnection capacity of the fuse (generally refers to its upper limit) is too large, it is likely to make the three-phase short-circuit capacity of the protected system smaller than the lower limit of the rated disconnection capacity of the fuse, which will make it difficult to extinguish the arc. In this situation, it may cause the fuse burning and explosion accidents finally. Some power supply units are still at the peak of the transformation of the agricultural network. When selecting this kind of fuse, the product quality must be strictly required and selected, to protect qualified equipment into the network. And do not to note its upper and lower limits of rated disconnection capacity.
 
 
 
Introduction of the structure
 
Drop out fuse is composed of two parts, base and arc extingu shingdevice . The bottom of extinguishing rcing pipe is equipped with possible rotation of the spring bracket, always make the fuse is in nervous condition, to ensure that the arcing tubes in  self- lockin state at he closing position .cWhen the crcuit and transformer oare verload or short circuit, the fuse, will be cut. The fse pumped rapidly from arcing tubes,. The extinguishing rcing tube dis esign edfor  solving the problem of different currenteon the same fuse by driving the gas out step by step.
 
 
Environmental conditions
 
1. Normal operating conditions: the ambient temperature is not higher than +40 degrees, not lower than -40 degrees; Elevation is not exceeding 1000m; Maximum wind speed shall not exceed 35m/s; Earthquake strength does not exceed 8 degrees.
 
2. The product shall not be used in the following places: places at risk of combustion or explosion; places of violent shaking or impact; There are electric conduction, chemical gas action and seriously polluted fog area.
 
 
Pay attention to situations of the operation
 
Under normal circumstances, drop out fuse is not allowed to be operated with load, only no-load equipment (line) is allowed. However, power distribution transformer with rated capacity less than 200kVA and 10kV distribution line branch line in agricultural network are allowed to operate with load according to the following requirements:
(1)The operation shall be performed by two people (one to monitor and one to operate), but the operation shall be conducted by wearing tested insulating gloves, insulating boots and goggles, and using qualified insulating bars with matching voltage levels. It is prohibited to operate in the climate of thunder or heavy rain.
(2) During the operation of the brake, the general rule is to first pull the intermediate phase, then pull the leeward side phase, and finally pull the windward side phase. This is because the distribution transformer is changed from three-phase operation to two-phase operation. When the center phase is pulled, the arc spark of arc generated is minimal, which will not cause short circuit between the two phases. Then it is to pull the leeward side phase, because the center phase has been pulled apart, the distance between the leeward side and the windward side phase has doubled, even if the overvoltage is generated, the possibility of causing the alternate short circuit is very small. And the upwind phase is finally broken, there is only capacitance to the ground, and the spark is already very slight.
 
(3) When closing the tubes, the operation sequence is opposite. First close the windward side phase, then the leeward side phase, and finally close the middle phase.
 
(4) Operating fuse is a frequent project, which will cause contact damaged. It will cause the contact burns if it is not noticed. And it will make contact overheat and spring annealing, which will result in vicious circle. Therefore, when the tube is pulled or closed, the force should be moderate. After the tube is closed, carefully check that the tongue of the "duck mouth" can be tightly buckled to more than two-thirds of the length of the tongue. You can check it by pushing the "duck mouth" several times by using the brake rod hooking the upper "duck mouth". Then try it like this several time to ensure it is well closed. When the switch is not in place or secure, the static contact pressure on the fuse is insufficient, resulting in contact burns or the fuse falls by itself.