Home - Blog

Types of Fuses: The Ultimate Guide for Fuses

About types of fuses,Every electronic application needs a circuit. But, circuits are fragile and will get damaged when there’s a flow of excessive current or electrical faults. 

So, if you’re looking for a way to protect your circuits from damage, you’re in the right place.

Moreover, various things can cause an overflow of current in a circuit. It could be from wrong connections, incorrect wirings, or human error.

Plus, you can’t predict when an overflow will occur. Thus, it’s best to prepare for such events.

Luckily, all you need is a fuse.

This article will show you everything you need to know about fuses, their different applications, and how to choose one.

Are you ready? Let’s dive in.

What is a Fuse?

A Fuse

A Fuse

Circuit safety is the specialty of a fuse. A fuse is an electrical safety device. It has a conductive strip that melts and separates whenever there’s an overflow of current. It would help if you always connected a fuse in series with the electrical components—you want to protect.

So, when the fuse opens (blows), it stops the flow of current through the components by opening the entire circuit. However, connecting the fuse in one branch of a parallel circuit won’t affect the flow of current in other branches.

Additionally, you’ll find that manufacturers place fuse wires within a safety sheath to minimize the hazards of the wire burning up with violent force.  When this happens, it creates an Electric arc blast. Usually, this occurs during severe overcurrents.

Fuses have various sizes and shapes. However, manufacturers design each fuse to protect electronic devices with certain electrical parameters. These parameters represent the operating current, speed, time, operating voltage, and fuse element melting of the fuse.

Types of Fuses– How Fuses Thoroughly Work?

As mentioned earlier, the fuse’s primary job is to disrupt the circuit if there is excess current flow. Thus, protecting the components from damage.

But, how does it protect the circuit?

The most basic type of fuse equips a resistive element because of its melting point. As current flows into the element, it creates a tiny voltage drop across the element (small enough not to affect the circuit downstream). This process dissipates some power as heat. Thus, increasing the resistive element’s temperature.

However, the temperature increase won’t dissolve the filament—if the voltage is normal. But, if the voltage increases beyond the fuse rated current, the resistive element interrupts the circuit by melting. The electric current is always the cause of the heating effect. Additionally, the length and thickness of the resistive element decide the rated voltage.

You can make fuse elements from copper, aluminum, silver, zinc, or their alloys for predictable trip currents. However, the element you choose must not corrode or oxidize over a period of time.

Types of Fuses– Characteristics of Fuses

The fuse is the first device used for protection in electronics. Though a fuse isn’t as flexible as a circuit breaker, it is reliable for high-performance devices. Plus, fuses are still fundamental in most applications. So, here are some characteristics to look out for before buying or designing your fuse:

Type of Fuse

You can identify fuses by two letters according to your applications (more details later). For low voltage applications, we have gG and aM fuses.

The gG fuse cartridge is mainly for general purposes. These fuse cartridges protect the circuits from high and low overflows and short circuits. Also, these cartridges have black markings.

On the other hand, fuse cartridges protect electric motors from short circuits and high overloads. You can calculate these cartridges to resist specific temporary overloads. aM fuses have green markings.

Conventional Currents

We have two conventional currents, which include fusing and non-fusing.

The conventional fusing current (If) is the current value that makes the cartridge melt before the conventional time runs out.

While the conventional non-fusing current (Inf) is the current value, the fuse can withstand without melting. 

Value table for conventional currents

Value table for conventional currents

Selectivity

Currents flow across multiple protection devices in series. Also, you can calculate and distribute these devices according to the different circuits you want to protect. Thus, selectivity happens when only the protection device of the faulted circuit operates.

Rated Currents and Voltages

The rated current is the current passing a fuse without setting it off. It is the voltage you can use to operate the fuse. In other words, it is the continuous current allowed across a fuse. As mentioned earlier, the two letters on your fuse determine its application. Here’s a more detailed description:

Rated currents and voltages table

Operating Zone

The operating zone is what determines the operating time of the fuse with the current crossing it. You must know the operating characteristics of your fuse if you want to calculate the discrimination of the different protective devices.

Breaking Capacity

Your breaking capacity must at least be equal to the short-circuit current. The higher the breaking capacity, the stronger the fuse. Furthermore, high breaking capacity fuses can limit short circuits reaching up to 100 000 A RMS.

Types of Fuses– Different Types of Fuses

Here is a list of the different types of fuses.

  1. DC fuses
  2. AC fuses
  3. Cartridge fuses
  4. High voltage fuses
  5. Thermal fuses
  6. Automotive, blade fuses, or bolted type fuses
  7. D-type cartridge fuses or D-type fuse
  8. Rewireable fuse
  9. Resettable fuses
  10. HRC (high rupturing capacity) fuse or link type cartridge fuse
  11. Low voltage fuses
  12. Cartridge fuses
  13. Drop out fuses
  14. Striker fuses
  15. Switch fuse
  16. Time-delay fuses

Types of Fuses– Symbol of a Fuse

Here are the standard IEEE/ANSI fuse symbols: 

IEEE Symbol

IEEE Symbol

ANSI Symbol

ANSI Symbol

Also, here’s the IEC fuse symbol:

IEC fuse symbol

IEC fuse symbol

Types of Fuse

Fuses have two main categories, which include DC fuses and AC fuses. There are different types of fuses under each category. So, let’s take a deeper look.

DC Fuse

The DC fuse is different from the AC fuse when it comes to size. It’s bigger because of the constant values of direct current circuits. When the current rating goes past the maximum current limit, the metallic fuse wire melts and disconnects the rest of the circuit from the power supply. So, here are the different types of DC fuse:

Cartridge Fuses

The cartridge fuse is a common type of fuse you can see in most circuits. Also, a glass envelope (terminated by metal caps) contains the fuse element. Since it’s a glass tube, you see when the fuse blows and the metallic wire.

Resettable Fuses/Polyfuse

These types of DC fuses have self-reset capabilities

Carbon black particles (conductive element) inserted in organic polymers make up the structure of this fuse. So, when the circuit generates heat, the organic polymer expands and forces carbon black particles apart. Thus, reducing the conductivity until no voltage flows.

Overvoltage Suppression

Fuses can’t always save your circuits from voltage spikes. However, you can pair your fuse with an overvoltage protection device to protect your circuits from current and maximum voltage spikes.

Metal oxide varistors (MOVs) and negative temperature coefficients (NTCs) are good examples of overvoltage suppression.

Automotive Fuses

These fuses protect automotive electronic systems that run up to 32v and 42v. The automotive fuse has a blade form with color codes that shows the rated current. 

Types of Fuses--Blade type fuse

Blade type fuse

Semiconductor Fuses

The amount of power a semiconductor can dissipate increases according to current flow. Thus, semiconductors work for super-fast fuses. Plus, the fuses can safeguard semiconductor switching devices that can pick up the smallest current spikes.

AC Fuses

The signals from AC currents vary from minimum to maximum and oscillate 50 to 60 times per second. During these oscillations, the AC voltage touches the 0v and terminates the arc between the melted electrodes. Thus, AC fuses are smaller when compared to DC fuses in electrical equipment. 

Here are the different types of AC fuses:

High Voltage Fuses

You can use these fuses for high voltage AC transmission lines—for voltages that climb higher than 100 kilovolts.

HRC Fuses

The HRC fuse is a cartridge-type fuse that equips a transparent steatite envelope. Quartz powder and non-conducting liquid type fill-up the insides of the fuse. Plus, it can work as a dousing agent. Plus, the fuses work better for currents with high faults.

Expulsion Fuses

The main components of this fuse are chemicals like boric acid, which generates gases when heated. These gases act as extinguishers that handle the arcs at the end of the fuse.

Types of Fuses– Advantages and Disadvantages of Electric Fuse

Here are the pros and cons of using an electric fuse:

Pros

  • The fuse is the most inexpensive protection device in any electrical circuit
  • The fuse is easy to operate
  • You can make the operation time of a fuse smaller than that of a miniature circuit breaker
  • Zero maintenance
  • Allows current limiting in the event of a short-circuit
  • Fuses can stop huge short circuit currents without generating flame, gas, smoke, or noise

Cons

  • You’ll have a blown fuse after a short-circuit or overload
  • Fuses connected in series are difficult to discriminate unless they have different sizes

Types of Fuses– Applications of Different Types of Fuses

You can use the different types of electrical and electronic fuses for various electrical systems and electronic applications. So, here are some of the applications of fuses:

  • Motors and transformers
  • Digital cameras
  • Laptops
  • Printers
  • DVD players
  • Instrument transformers
  • Cell phones
  • Air-conditioners
  • Scanners
  • Game systems
  • Power systems
  • Power transformers
  • Light bulb

Types of Fuses–How to Choose a Fuse?

Here are a few steps to help you choose the right fuse:

  1. Know the type of voltage 
  2. Monitor the ampere rating of the circuit your fuse will protect
  3. Make sure the fuse matches the fuse holder
  4. Inspect the fuse (in case you need to replace the internal element)
  5. Choose a fuse with an inspection window

Wrapping Up

Finally, use an ohmmeter to check your fuses. But, ensure you pull the fuse from its holder before using the meter.

Also, if your fuse has an inspection window, it is easier to detect when you have a blown a fuse. A quick visual check is all you need when looking for problems on a circuit.

Well, that concludes this article. If you have any questions, feel free to reach us. We’ll be happy to help.

Avatar photo
Hommer Zhao
Hi, I am Hommer, the founder of WellPCB. So far, we have more than 4,000 customers worldwide. If you have any questions, you can feel free to contact me. I really appreciate any help you can provide.

Services