Overview
The drop fuse and load switch fuse are outdoor high-voltage protection devices. They are connected to the incoming line or distribution line of the distribution transformer. These are mainly used to protect transformers or lines from short circuit, overload and switching current. The drop fuse consists of an insulator bracket and a fuse tube. The static contacts are fixed on both sides of the insulator bracket, and the movable contacts are installed on both ends of the fuse tube. Inside the fuse tube is a fire hose. The exterior is made of phenolic composite paper tube or epoxy glass. The load switch fuse provides extension auxiliary contact and arc extinguishing chamber closure for opening/closing the load current.
During normal operation, the fuse is pulled to the closed position. Under fault current conditions, the fuse link melts and forms an arc. This is the situation of the arc extinguishing chamber. This creates high pressure in the tube and causes the tube to separate from the contacts. Once the fuse melts, the strength of the contacts will relax. The circuit breaker is now in the open position and the operator needs to turn off the current. The moving contacts can then be pulled using insulated levers. Main contact and auxiliary contact are connected.
maintain
(1) In order to make the fuse operate more reliably and safely, in addition to strictly selecting the qualified products and accessories (including fusible parts) produced by formal manufacturers according to the requirements of the regulations, the following matters shall be paid special attention to in the operation and maintenance management:
① Check whether the rated current of the fuse matches the melt and load current values properly. If the matching is improper, it must be adjusted.
② Each operation of the fuse must be careful and careful, not careless, especially the closing operation. The dynamic and static contacts must be in good contact.
③ The standard melt must be used in the melt pipe. It is prohibited to use copper wire and aluminum wire instead of the melt, and it is not allowed to use copper wire, aluminum wire and iron wire to bind the contact.
④ For newly installed or replaced fuses, the acceptance process shall be strictly carried out, and the quality requirements of the regulations must be met. The installation angle of the fuse tube shall reach about 25 °.
⑤ The fused melt shall be replaced with a new one of the same specification. It is not allowed to connect the fused melt and put it into the melt tube for further use.
⑥ The fuse should be inspected regularly, at least once a month at night, to check whether there is discharge spark and poor contact. If there is discharge, there will be a hissing noise, which should be handled as soon as possible.
(2) The following inspections shall be carried out for fuses during spring inspection and outage maintenance:
① Whether the contact between static contact and moving contact is consistent, tight and intact, and whether there is burn mark.
② Whether the rotating parts of the fuse are flexible, rusty, inflexible, etc., whether the parts are damaged, and whether the spring is rusted.
③ Whether the melt itself is damaged or not, and whether there is excessive heating elongation and becomes weak after long-term power on.
④ Whether the arc suppression tube for gas production in the melting tube is burned, damaged and deformed after exposure to the sun and rain, and whether the length is shortened after multiple actions.
⑤ Clean the insulator and check whether there is damage, crack or discharge trace. After removing the upper and lower leads, use a 2500V megger to test the insulation resistance, which should be greater than 300M Ω.
⑥ Check whether the upper and lower connecting leads of the fuse are loose, discharged or overheated.
The defects found in the above items must be carefully repaired and handled.
Melting tube structure:
The fuse is made of flberglsaa, which is moisture and corrosion resistant.
Fuse base:
The product base is embedded with mechanical structures and insulators. The metal rod mechanism is installed with special adhesive material and insulator, which can withstand short circuit current to turn on the power.
Moisture-proof fuse has no bubbles, no deformation, no open circuit, large capacity, anti-ultraviolet, long life, superior electrical properties, dielectric strength and excellent mechanical rigidity and dedication ability.
The whole mechanism is neutral, easy to install, safe and reliable.
