What Occasions Are Different Types of Fuses Suitable For?

Low-voltage fuses remain commonly used electrical protection devices in industrial, commercial and new energy fields.

Although circuit breakers are being used more and more widely, fuses are still preferred in some situations. This is mainly due to their fast action response, strong breaking capacity and relatively simple and reliable structure.

Fuse Classification Standards

IEC 60269 is a series of standards for low-voltage fuses issued by the international electrotechnical commission, which uses a two-letter classification system to identify the functions and applicable objects of fuses.

The first letter indicates the main working mode of the fuse:

g =  general-purpose (provides overload and short-circuit protection)

a = associated (short-circuit protection only)

The second letter indicates the protected object or application (such as G = cable/conductor, M = motor, R = semiconductor, etc.)

Fuse Types and Their Applications

Fuse Type	Protection Range	Typical Applications	Main Characteristics
gG/gL	Full Range	General circuits, cables, distribution systems	Most common type; provides overload and short-circuit protection
aM	Partial Range	Motor circuits	Withstands high inrush current; requires separate overload protection
gM	Full Range	Motor protection	Complete motor protection; handles high starting current without derating
aR	Partial Range	Semiconductor devices, rectifiers	Ultra-fast operation; protects sensitive electronic components
gPV	Full Range	Photovoltaic systems	Specifically designed for DC PV applications; handles reverse current

Why Do Some Manufacturers Prefer Using Fuses Instead of Circuit Breakers?

Although circuit breakers can be reset and reused, in some cases, the advantages of fuses are more obvious, and thus they are widely chosen by many manufacturers.

• DC performs significantly better than circuit breakers

The arc-extinguishing capacity of circuit breakers is limited in DC environments

• Lower cost

- Especially suitable for photovoltaic power stations, factory power distribution, and large-scale systems

• Higher reliability

- No mechanical contacts, so it will not malfunction due to aging

• Smaller size, more flexible layout
• Higher short-circuit breaking capacity

Conclusion

Low-voltage fuses remain indispensable components in electrical protection schemes and offer advantages that circuit breakers cannot match in many applications. From general-purpose gG fuses to dedicated aR types for semiconductors and gPV fuses for solar applications, the diverse range of fuse types ensures that the best solution is available for almost all protection scenarios.

Although the convenience of resettable circuit breakers makes them attractive in some applications, fuses offer excellent current limiting, higher breaking capacity, greater reliability and more cost-effective protection for high fault current applications. The key to effective protection lies in understanding the specific requirements of the electrical system, and choosing the appropriate fuse type and rating accordingly.