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How does a fuse work?

Time:2022-04-29   Author:ABPower   Browse:

How does a fuse work?

Fuse is an electrical appliance in which with a metal (Silver, Copper etc)  conductor belt, It's used as a melting part to break a circuit. When the overload or short-circuit current passes through the melt  in series,  the melting belt itself will heat and melt, thus protecting the power system,  various electrical equipment and household appliances. So the melting belt is the key element to control the fusing characteristics.


When the overload current is small, the fusing time is long; when the overload current is large, the fusing time is short. Therefore, in a certain range of overload current until the current returns to normal, the fuse link will not be melted and can continue to be used.

How does a fuse work.png

Why we use fuse as an overcurrent  protection  device? How fuse works when overcurrent?

Fuse is a kind of overcurrent  protection device, which is made according to the principle that the current exceeds the specified value for a certain period of time with the heat generated by itself to melt .

Then fuse element is melting, thus making the circuit open.

Fuse is widely used in low-voltage distribution system, control system and electrical equipment. As short-circuit and over-current protection, fuse is one of the most common protection devices.

When in use, the fuse is connected in series in the AC/DC protected circuit. When the current of the protected circuit exceeds the specified value, and after a certain period of time, the heat generated by the melt itself melts the fuse link belt inside, so that the circuit is disconnected and plays a protective role.

What's the uses of fuse?

1) For residential and similar occasions, normally fuse class GG are applicable;

2) For industrial equipments, Fuse class sizing GG, GM or am are used;

No matter which usages, safety is the first, Pls consult professional engineer to select the fuse to you.

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What's the standard types of fuses?


*For residential use, D type cartridge fuse, rated current 100A, designated type GG (IEC60269-1 and 3).

The fuse Part # such as: C22G100

*For industrial applications, cartridge, type GG (general); GM, am (for motor circuits), IEC 60269-1 and 2.

Example fuse Part #’s: FWK-15A20F, FWS-10A20F

FWK-15A20F Bussmann fuse1.png

Why there is 2 characteristic on fuse class?

Here is a short explanation:

A, The first letter indicates the fusing range:

*"G" refers to the fuse with full capacity(Both Overcurrent and overload protection fuse).;

Such as SC series fuse: SC-1, SC-10, SC-20, SC-60 etc.

*"A" denotes a fuse with a partial range of fusing capacity(Overcurrent or overload protection fuse).

Such as Cylindrical fuse links: C10M6, C10M10 etc.

 C10M10 bussmann fuse.png

The second letter indicates the fuse application category, and this letter accurately describes the time current characteristics, conventional time and current.

For example:

*"GG" refers to the universal fuse with full fuse capacity;

Related Bussmann fuse part # are: C10G6, C10G12, C10G32;

*"GM" refers to the fuse used to protect the full range of fusing capacity of motor circuit;

HRC Fuse links are: NSD20M36, ESD63M100, NITD32M50, AAO32M63 etc.

*"Am" denotes a fuse used to protect a part of the range fusing capacity of the motor circuit.

Ferrules fuses are: C14M25, C22M10, C22M80 etc.  

Some fuses are with a "fuse blown" mechanical indicator. When the current flowing through the fuse exceeds the given value for a certain time, the fuse device cuts off the circuit through the fuse. The current / time relationship is given by each type of performance curve. Then you can figure out from the indicator color that this fuse blown, needs to be changed.

LPJ-SPI fuse with indicator.jpg

Why fuse are used for overload protection? What's the difference between fuse and motor on overload protection?

Fuses are designed for overload protection.

That's two different things. The overload protection of the motor ensures that the motor load does not damage the motor itself.Fuses protect power supplying circuit, which should be higher than overload relay in order, but it cannot be said that there is no overload protection function.It's just an extreme form (just disconnect the circuit).

What's the advantage of fuse?

Comparing with circuit breaker, Fuse is an short circuit protection device with cheap price, simple structure, convenient use, and effective control.

Difference between fuse and breaker 2.jpg

What are fuse made of?

Fuse elements are mainly composed of 4 parts: the fuse link, fuse tube/cartridge, the fuse end blades and the Arc-quenching filler(Normally sand).

fuse structure.png


For more fuse questions, pls feel free to consult us at:



New industry Technology regarding to Bussmann fuse, ABB breakers, Amphenol connectors, HPS transformers, etc.