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China 15kV Drop-Out Fuse Cutout - Reliable Suppliers & Factory for 10kV Distribution Line Protection
Working Principle
The moving contacts at both ends of the fuse tube are fastened by the fuse (melting element). After pushing the upper moving contact into the protruding part of the "duckbill", the upper static contact made of phosphor copper sheet etc. presses against the upper moving contact, so that the fuse tube is firmly clamped in the "duckbill".
When the short-circuit current passes through and fuses the fuse, an electric arc is generated. The steel paper tube lined inside the fuse tube produces a large amount of gas under the action of the electric arc. Since the upper end of the fuse tube is sealed, the gas is sprayed downward to extinguish the electric arc.
Due to the fuse melting, the upper and lower moving contacts of the fuse tube lose the tension of the fuse. Under the action of the fuse tube's own gravity and the spring sheets of the upper and lower static contacts, the fuse tube falls rapidly, disconnecting the circuit and cutting off the faulty line section or faulty equipment.
Applicable Environment
The 10kV drop-out fuse is suitable for outdoor places where the ambient air is free of conductive dust, corrosive gases, flammable, explosive and other hazardous environments, and the annual temperature difference ratio is within ±40℃.
Its selection is based on two key parameters:
- 1 Rated Voltage — The rated voltage of the fuse must match the rated voltage of the protected equipment (line).
- 2 Rated Current — Must be correctly selected based on the load requirements of the protected circuit.
Installation Tips
- 1 During installation, the melting element should be tightened so that it is subjected to a tension of about ~24.5N, otherwise it is easy to cause contact heating.
- 2 The fuse should be firmly installed on the crossarm (frame) without any shaking or wobbling.
- 3 The fuse tube should have a downward inclination angle of 25° ± 2° to facilitate the rapid fall of the fuse tube by its own weight when the melting element fuses.
- 4 The fuse should be installed on a crossarm (frame) with a vertical distance of ≥ 4m from the ground. If installed above the distribution transformer, maintain a horizontal distance of > 0.5m from the outermost contour boundary of the transformer to prevent accidents caused by the falling of the fuse tube.
- 5 After closing, the duckbill tongue must hold more than 2/3 of the contact length to avoid accidental self-falling during operation. The fuse tube should not push the duckbill to dead-stop to prevent the fuse tube from failing to fall in time after the melting element fuses.
- 6 The melting element used must be a standard product from regular manufacturers with sufficient mechanical strength. Generally, the melting element is required to withstand a tension of at least 147N.
- 7 The 10kV drop-out fuse is installed outdoors, requiring a phase-to-phase distance of > 70cm.
Frequently Asked Questions
Q
How does a 10kV drop-out fuse extinguish an electric arc?
When a short-circuit current fuses the melting element, the steel paper tube lining inside the fuse tube generates a large amount of gas under the arc's heat. Since the upper end of the fuse tube is sealed, the gas is forcefully expelled downward, effectively extinguishing the electric arc.
Q
What environments are 10kV drop-out fuses suitable for?
They are designed for outdoor installations where the ambient air is free of conductive dust, corrosive gases, and flammable or explosive hazards. The operating temperature range must be within an annual difference ratio of ±40℃.
Q
What is the correct inclination angle for installing the fuse tube?
The fuse tube must be installed at a downward inclination angle of 25° ± 2°. This angle ensures that when the melting element fuses, the fuse tube falls rapidly under its own gravity to disconnect the circuit promptly.
Q
What tension should the melting element withstand during installation?
During installation, the melting element should be tightened to a tension of approximately 24.5N. Additionally, the melting element must be a standard product capable of withstanding a minimum mechanical tension of 147N to ensure reliable operation.
Q
What is the minimum installation height for a drop-out fuse from the ground?
The fuse must be installed at a vertical distance of not less than 4 meters from the ground. When mounted above a distribution transformer, a horizontal clearance of more than 0.5 meters from the outermost boundary of the transformer must be maintained to prevent accidents from falling fuse tubes.
Q
Why is it important that the duckbill tongue holds at least two-thirds of the contact length?
Ensuring the duckbill tongue holds more than two-thirds of the contact length prevents accidental self-falling of the fuse tube during normal operation. However, the tube must not be pushed all the way to a dead-stop, as this could prevent the tube from falling in time when the melting element fuses, delaying fault isolation.
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