Do drop-out fuses need to be tested?
Drop-out fuses do not need to be tested, but the fuse size must be determined according to the actual load and products from manufacturers approved by the power department must be selected. For safety reasons, European-style cable joints should not be too large. Choose the closest grade above the rated load. Less than or equal to the maximum rated current of the power department H.
To be on the safe side, check the safety or transportation regulations.
How to choose a drop-out fuse
Select and install according to the voltage level and capacity of the distribution transformer. The rated voltage of the fuse RW7-10/100A fuse should be greater than or equal to the actual highest working voltage. The three-phase short-circuit capacity of the distribution transformer must be less than the upper limit of the rated breaking capacity of the drop-out fuse, but must be greater than the lower limit of the rated breaking capacity. High-voltage drop-out fuses are generally suitable for outdoor places where there are no conductive dust, corrosive gases, flammable, explosive and other dangerous substances in the surrounding air, and the annual temperature changes are not higher than 40 degrees Celsius and not lower than minus 30 degrees Celsius. The drop-out fuse must have all parts intact, the shaft should be smooth and flexible, the casting should be free of cracks, blisters and rust, the porcelain body should be in good condition, and the fuse should not expand or bend due to moisture absorption.
Installation of drop-out fuses:
The installation position of the fuse must meet the requirements and should be installed on an iron cross arm (frame) with a vertical distance of not less than 2.5 meters from the ground. If it is installed above the distribution transformer, it should maintain a horizontal distance of more than 0.5 meters from the outermost contour boundary of the distribution transformer to prevent the fuse from falling and causing other accidents. When a 10 kV drop-out fuse is installed outdoors, the distance between phases is required to be no less than 0.7 meters, and when installed indoors, the distance is no less than 0.5 meters.
The installation of the drop-out fuse must be firm (the melt can withstand a pulling force of about 24.5 Newtons), the European-style cable joints are arranged neatly, and the height is consistent. The vertical angle between the axis of the fuse tube and the ground should be 15 to 30 degrees. The operation is flexible and reliable, and the contact is tight. The contact blade contact RTOHDLRT0-600 600A on the fuse tube should have a certain compression stroke. It is required that the duckbill tongue can hold more than 2/3 of the contact length after closing to avoid malfunction of falling on its own during operation. However, the fuse tube cannot push the duckbill to prevent the fuse tube from falling in time after the melt melts. The upper and lower leads should be pressed tightly, and the connection with the line conductors should be tight and reliable.
