Fuse-links are not “universal.” Each application — from a 10 kVA transformer to a 36 kV medium-voltage switchgear — requires a suitable fuse type, adapted to voltage, current, and load characteristics.
Choosing the correct type of fuse means:
Effective protection against short-circuits and overloads
Safe and continuous operation of the installation
Reduced risk of cascading failures
1. By voltage level:
Low Voltage (LV) – up to 1000 V; used in residential and industrial panels
Medium Voltage (MV) – 1 kV – 36 kV; used in substations, switchgear, and distribution networks
High Voltage (HV) – above 36 kV; rarely used, mainly in power transmission networks
2. By shape and mounting:
Cartridge fuses – cylindrical, mounted in special holders (e.g., gG, aM)
NH fuses (with blades) – industrial type, robust, equipped with extraction handles
MV-type fuses – ceramic tube with metallic caps, used in medium-voltage applications
Embedded fuses (miniature, automotive, SMT) – for electronics, automobiles, and PCBs
3. By operating characteristic:
GG (general purpose) – protects against both short-circuit and overload
AM (motor) – protects only against short-circuit, ideal for heavy motor starts
GTr (transformer) – dedicated to transformer protection
AR (semiconductor) – ultra-fast reaction, for sensitive devices and electronic circuits
In medium-voltage systems, the most common are barrel-type fuses — ceramic tubes filled with quartz sand, standardized in both length and diameter.
Selecting the type of fuse is not just a matter of current and voltage — it also depends on the application, reaction times, and the level of protection required.
In the next article, we will explore in detail how a medium-voltage fuse is constructed and what factors influence its performance.
CNC LTD is a Romanian manufacturer of medium-voltage fuses, offering ISO-certified quality and proven reliability for energy utility companies worldwide.
