High Speed Fuses

What are high speed fuses?

High speed fuses are reliable, very quick acting circuit protection devices designed to protect semiconductor devices such as rectifiers and thyristors from potentially damaging short circuits and power surges. High speed fuses have been specifically designed to minimize peak current let-through and arc voltage.

What are high speed fuses made of?

This type of fuse consists of one or more current carrying elements that are enclosed within a chamber. High-speed fuses usually contain one or more current sensitive elements and each one has a reduced cross section which provides a measured resistance which determine the current rating of the fuse. Elements can be made of silver, silver-plated copper, copper etc. The chamber is fitted with contacts, so the fuse be easily inserted and removed.

Typical body materials include glass-melamine, which is strong and resistant to breaking, and ceramic which has high heat dissipation and temperature withstand capabilities. Unlike general industrial fuses, high-speed fuses don't have intentional time-delay features.

High-speed fuses contain a quartz silica crystal filler which contributes to current-limiting ability. Fillers help with heat balance and element stability, allowing for smaller element cross sections improving short-circuit performance. The most common types of high speed fuse are North American, Square Body, Cylindrical and British Standard (BS88)

What are full range and partial range fuses?

High-speed fuses are classified into two broad categories, full range high-speed fuses and partial range highspeed fuses. The IEC 60269 standard classifies fuse operating characteristics by utilisation categories such as gG, aR, gR, aM, etc. Full range high-speed fuses provide protection to both overload and short circuit overcurrent conditions and have a gR utilisation category. Partial range high-speed fuses provide protection to short-circuit overcurrent conditions with an aR utilisation category.

Kempston Controls stocks a range of high-speed fuses from brands including Mersen and Eaton Bussmann designed to suit whatever your application requires. Give our dedicated sales team a call on +44 (0) 1933 411411 or use the contact form above to discuss your high-speed fuse requirements.