A Horn Gap Fuse (HGF), also often referred to simply as an HG Fuse, is a protective device utilized primarily in medium-voltage overhead power distribution systems (typically 11 kV to 33 kV). Its fundamental role is to protect expensive equipment like distribution transformers and power lines from damage caused by overcurrent or short-circuit conditions. The device is characterized by its simple, robust, and open-air construction, which makes it suitable for outdoor, exposed installation on utility poles and substation structures.
Maintaining Horn Gap Fuses (HG Fuse)
The Horn Gap Fuse (HGF) is the simplest of the three in terms of mechanical complexity, relying on open air to extinguish the arc. Its spare parts are minimal but crucial for proper functioning.
The essential spare parts for an HG Fuse include:
• Fuse Wire/Link: Like the DO fuse, this is the main part that is sacrificed. It is the thin, exposed wire that bridges the gap between the horns. Its correct rating is vital for protection.
• Arcing Horns/Strips: These are the V-shaped metallic strips (often aluminum, copper, or galvanized iron) that guide the arc upwards. While generally robust, they can be damaged by severe arcing or environmental corrosion, impacting the arc-stretching effect, and may need replacement.
• Insulators: Similar to the AB switch, the porcelain or polymeric insulators supporting the horn structure are the main non-conducting components that need replacement if mechanically or electrically damaged.
The simplicity of both the DO and HG fuses means that ensuring a stock of the correct fuse links and the structural integrity of the insulators and metallic contacts is the core focus of their spare parts inventory.