drop out fuse
E-Glass fiberglass core for mechanical strength
One-piece crimped-on end fittings & robust center-bracket
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Drop-out Fuse Cutouts & Load Switching Fuse Cutouts for Reliable High-Voltage Protection
Drop-out fuse cutouts (MV drop-out fuses) and load switching fuse cutouts are essential outdoor high-voltage protection devices. They are commonly installed at the incoming feeders of distribution transformers or along power distribution lines.
Purpose & Functionality
These fuse cutouts serve a critical role in safeguarding transformers and power lines from short circuits, overloads, and switching surges.
A drop-out fuse unit consists of:
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Insulator supports – providing structural stability.
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Fuse tube – containing internal arc-extinguishing components.
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Static contacts – fixed on either side of the insulator support.
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Moving contact – positioned at both ends of the fuse tube.
The fuse tube’s inner structure features an arc-extinguishing lining, while its exterior is typically composed of a durable phenolic compound paper tube or an epoxy glass material.
Operation & Safety Mechanism
In load switching fuse cutouts, auxiliary stretch contacts and an arc-extinguishing enclosure facilitate controlled current switching. Under normal conditions, the fuse link maintains a closed circuit. However, during a fault event:
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The fuse link melts due to excessive current, generating an electrical arc.
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The arc-extinguishing tube activates, creating high internal pressure.
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This pressure forces the fuse tube to disengage from its contacts, breaking the circuit.
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As the fuse element melts, the contact tension is released, leaving the cutout in an open state.
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To fully disconnect the circuit, an operator must manually pull the moving contact away using an insulated operating rod.
