Outdoor windproof 35KV high-voltage fuse

Outdoor windproof 35KV high-voltage fuseIntroduction:

Simple protective appliances are used to protect electrical equipment from damage caused by overload and short-circuit currents; Select different types of high-voltage fuses according to installation conditions and purposes, such as outdoor drop out and indoor type. For some equipment, a series of high-voltage fuses should be selected; The fuse we often refer to is a type of fuse. The main purpose is to provide overload and short-circuit protection for electrical equipment such as high-voltage transmission lines, voltage transformers, and voltage transformers. 2. Drop out fuse is a common short-circuit protection switch for branch lines of distribution lines and distribution transformers. It has the characteristics of economy, easy operation, and strong adaptability to outdoor environments, and is widely used in the primary side of distribution lines and distribution transformers for protection and equipment switching operations. Installed on the branch of the distribution line, it can reduce the range of power outages. Due to its obvious disconnection point, it has the function of an isolation switch, creating a safe working environment for maintenance lines and equipment, and increasing the safety of maintenance personnel. A drop out fuse with a pulling load, equipped with elastic auxiliary contacts and an arc extinguishing cover, used to switch the rated load current. Usage and Implementation Standards: This product is used for branch lines of 10-35kV distribution lines and primary side of distribution transformers, for overload and short-circuit protection, and for switching rated load currents.

3.Outdoor windproof 35KV high-voltage fuseworking principle

The drop out fuse consists of three parts: insulator, contact conductive system, and fuse tube. During normal operation, the fuse locks the movable joint on the melting tube, and the melting tube is in a closed state under the pressure of the upper contact. When a fault occurs, the fuse melts and an arc is generated inside the melting tube. The arc extinguishing tube lining the melting tube decomposes a large amount of gas under the action of the arc, which produces a strong dissociation effect when the current crosses zero and extinguishes the arc. Due to the melting of the fuse, the release of the movable joint causes the melting tube to sag, rapidly falling under the elastic force of the upper and lower contacts and the weight of the melting tube, forming a clear disconnect gap.

4. Selection of fuses

The short-circuit capacity of the installation location should be within the rated breaking capacity range of the drop out fuse. If the upper limit is exceeded, the molten tube may explode due to excessive current and gas production; If it is below the lower limit, it is possible that the arc cannot be extinguished due to insufficient current and insufficient gas production. Therefore, when selecting the rated capacity of a drop out fuse, it is necessary to consider not only matching its upper limit breaking current with the large short-circuit current at the installation location, but also paying attention to the relationship between its lower limit breaking capacity and the small short-circuit current at the installation location. Considering that the drop type high-voltage fuse serves as the main protection for internal faults in distribution transformers, with a protection range from the low-voltage fuse transformer side to the high-voltage fuse transformer side, and also serves as a backup protection for the low-voltage fuse, its lower limit breaking capacity should be selected based on the minimum short-circuit current of the low-voltage outlet two-phase short circuit.

5. Selection of fuses

The selection of fuses should ensure that they can quickly melt in the event of a short circuit inside the distribution transformer or in the high and low voltage outgoing bushings. In practice, the following principles are often followed for selection: for distribution transformers with a capacity of 160kVA or less, fuses should be selected at 2-3 times the rated current of the transformer; For distribution transformers with a capacity of 160kVA or above, choose 1.5 to 2 times. The selection of fuses must also consider whether the melting characteristics of the fuse can match the superior protection time, which is the key issue in determining whether fuse protection can be effective. The quick break protection action time of the distribution line is very short, about 0.1 seconds. According to the characteristic curve of the fuse, the current required to melt the fuse within 0.1 seconds should not be less than 20 times the rated current. This data is a necessary condition to ensure the coordination between the fuse and the head end circuit breaker.

6. Installation of drop out fuses

(1) During installation, the melt should be tightened (causing a tensile force of approximately 24.5N on the melt), otherwise it is easy to cause the contact to heat up.

(2) The fuse installed on the crossbar (frame) should be firm and reliable, without any shaking or shaking phenomenon.

(3) The melting tube should have a downward inclination angle of 25 °± 2 ° to facilitate the rapid drop of the melting tube by its own weight when the melt melts.

(4) The fuse should be installed on a cross arm (frame) with a vertical distance of not less than 4m from the ground. If installed above the distribution transformer, it should maintain a horizontal distance of at least 0.5m from the outer contour boundary of the distribution transformer to prevent other accidents caused by the melting tube falling.

(5) The length of the melting tube should be adjusted appropriately, and it is required that the duckbill tongue can hold more than two-thirds of the length of the contact after closing to avoid accidental dropping during operation. The melting tube should not be pushed to the death of the duckbill to prevent the melting tube from falling in time after melting.

(6) The melt used must be a standard product from a legitimate manufacturer and have a certain mechanical strength. Generally, the melt is required to withstand a tensile force of at least 147N.

(7) 10kV drop out fuses are installed outdoors, with a requirement for a phase to phase distance greater than 70cm.

7. Operation, maintenance and management of fuses

(1) Whether the rated current of the fuse device matches the current value of the fuse link and load appropriately, and if not, adjustments must be made.

(2) Each operation of the fuse must be careful and meticulous, and must not be careless, especially during the closing operation, which must ensure good contact between the moving and stationary contacts.

(3) It is advisable to avoid using drop out fuses to disconnect the rated breaking capacity multiple times in a row. For fuses with steel paper tubes on the inner wall of the fuse tube, the rated breaking capacity should not be disconnected more than three times in a row.

(4) The standard melt produced by a legitimate manufacturer must be used inside the melting tube. Copper wire and aluminum wire are prohibited from replacing the fuse link, and copper wire, aluminum wire, and iron wire are not allowed to be used to tie the contact.

(5) For newly installed or replaced fuses, strict inspection procedures must be carried out and they must meet the quality requirements of the regulations.

(6) After the fuse is blown, it should be replaced with a new melt of the same specification. It is not allowed to connect the melted melt and then install it into the melting tube for continued use.

(7) The fuse should be checked regularly, at least once a month at night, for any discharge sparks or poor contact. If it does not discharge, there will be a hissing sound, and it should be checked as soon as possibleArrange for processing