Cartridge fuses

Last Updated on February 12, 2023 by

Fuse cartridges have been produced for over 100 years, and there is now a large number in use around the world. They protect equipment and electrical networks, ensure that the effects of faults, which will inevitably occur, are limited, and maintain the continuity of supply to consumers.

In addition to electrical engineers, nearly all public members are aware of cartridge fuses, which are considered simple devices in all respects. Though their construction is not complex, they must be designed and manufactured with great care to ensure that they perform as expected. This article is all about cartridge fuses.

Cartridge fuses, what is it?

Cartridge fuses are electrical safety devices used to protect circuits and equipment from damage due to overloading or short-circuiting. They are cylindrical and typically made of metal or a metal alloy, with a fuse wire inside that will melt and break the circuit if the current exceeds a predetermined level. Cartridge fuses come in various sizes and ratings, allowing them to be used in various applications, from small electronic devices to large industrial systems.

Unlike other fuses, cartridge fuses are designed to be easily replaceable, making them a convenient and cost-effective solution for protecting against electrical faults. Additionally, cartridge fuses are readily available and widely used, making them a common and reliable choice for electrical safety in residential and commercial settings.

A cartridge fuse is an electrical safety device used to protect cables, power lines, and equipment from overloads and short circuits. The primary purpose of a cartridge fuse is to protect human life and systems. Cartridge fuses can be made from ceramic, porcelain, glass, etc.

Although miniature circuit breakers have taken their place in recent years, they can still be used in electrical applications.

Cartridge fuses Types 

Among the two types of cartridge fuses, the following are the most common:

Fast-acting cartridge fuses

Typically, small appliances such as toasters and hair dryers use this type of battery. Their primary characteristic is their ability to respond quickly to current flow, typically within 30 to 40 milliseconds.

Therefore, they are sometimes called fast-acting fuses. Their elements create a short circuit during melting and prevent current from flowing through the fuse. Because they have served their purpose, you should replace them immediately.

Read more:What Is A Rheostat? Its Types, Construction, Purpose And Applications

Cartridge fuses with time delays

To prevent fires or other damage from overheating and causing fire, these fuses are used when there is not enough time to shut down an electrical circuit.

 In contrast to quick-acting cartridges, they have a longer response time so that an overload has a longer time to cool before it melts the fuse. Among the other types based on their designs are:

Fuse-types with ferrules: These fuses are designed to be placed so that they are easily replaced. When the fuse melts, it closes the circuit.

Blade-type cartridge fuses

Fuse terminals are designed to be clipped onto these fuses. When the fuse melts, they have a long, thin blade that cuts through it.

It is common to find them in computers, printers, and other equipment that has low voltage circuits, and it is essential to limit the amount of time the circuit is energized.

Working of cartridge fuse 

When a cartridge fuse blows, it must be replaced with a new one because it is based on the principle of conductor melting.

When connected to an electrical circuit, the strips have a thin metal wire in the middle and two metal caps that serve as contacts. When more current flows through the thin wire than the nominal amount, it is designed to melt at a specific temperature. If the wire melts, it becomes an open circuit, and electricity cannot flow.

Construction of cartridge fuse

The ceramic outer casing can withstand pressure and thermal shock with a high breaking capacity. Copper-plated silver covers are used on the contacts. Filled cartridge fuses comprised fine quartz with a grain size of 300*m and high chemical purity. Granularity is tailored to match the thickness of the element and performance requirements.

Because filling materials conduct some of the heat energy away from the fuse element to the body, it is crucial to maintain the same packing density of the filling material during production. A low packing density may allow the arcs to expand very rapidly at high current levels, affecting the column voltage and thus the rate at which the current changes.

The methods for installing cartridge fuses include ferrules, blades, or screws. The voltages range from 125, 250, 600, and 1000 volts, with capacities between 1 and 1000 amperes. Unlike fuses intended for 250-volt service, fuses intended for 600 and 1000 volts are longer and will not fit the same fuse holders. In addition to different capacities of fuses, different fuse holders are also designed for different-sized fuses. Fuses with a capacity of 1 to 30 amperes fit one size of the holder, while fuses with a capacity of 35 to 60 amperes fit another size. As capacity increases, the diameter and length of high-capacity fuses increase, and they have knife-blade contacts.

Comparing cartridge fuses with other types of breakers and fuses

There are probably other types of fuses and breakers in your home in addition to the fuse box, such as time delay fuses, motor-protecting fuses, and circuit breakers. A cartridge fuse is the simplest circuit breaker, and it is used in many homes.

Electric overload protectors can add protection to specific circuits or devices in your electrical system.

Cartridge fuses versus time delay fuses

Time delay fuses have a longer delay time than cartridge fuses, so they are similar to cartridge fuses due to their much greater sensitivity to electrical current than cartridge fuse devices.

Circuit breakers vs. cartridge fuses

Circuit breakers are also used in homes and are similar to cartridge fuses, but they’re more sophisticated than cartridge fuses.

They have a mechanism that detects an electrical overload, and they can be reset in just a few seconds.

Designed for use on circuits that consume a lot of power, they ensure that they don’t overload the circuit regardless of how much power is consumed.

Pros of a cartridge fuse

The following are some benefits of cartridge fuses:

  • It has high braking power.
  • It is not prone to reclosing after the trip.
  • A good selectivity value characterizes it.
  • High levels of energy can be let through.
  • It is highly compact and straightforward to construct.
  • It can also be easily replaced.
  • It operates quickly.
  • The cost of the solution is low. 
  • It can be used at low and high temperatures.

Cons of a cartridge fuse

The following are some drawbacks of cartridge fuses:

  • There is a risk of a one-phase trip on three-phase lines.
  • There is a slow recovery time after a trip.
  • There are no accessories.
  • This is a one-time performance. Once it has been tripped, it should be changed.
  • It’s an outdated technology.
  • Generally, fuse carriers should be used instead.

Applications of Cartridge fuse 

Cartridge type fuses are used in the following applications:

  • Distribution panels and automation panels.
  • For the protection of measurement instruments.
  • Insulation of isolated transformers.
  • For the protection of surge arresters.
  • DC applications and solar applications.
  • For starting motors.

Cartridge Fuses: Where to Find Them

In many older electrical systems with fuse boxes (as opposed to modern breakers), there are two or more fuse blocks with two cartridge fuses each. The main fuse is located in one of the fuse blocks. This is the OCPD for the entire fuse box and all the branch circuits in the house. There are also blocks for large electric appliances, such as dryers, ranges, air conditioners, baseboard heaters, and electric water heaters.

Fuse blocks are accessible by pulling on the wire bail or handle to release the fuses. If something goes wrong, pull the block out with one hand to prevent electrocution. The block should be removed entirely from the box. Using a fuse puller, a pliers-like tool made of plastic, or another nonconductive material, you can draw a fuse from its block. Just like the originals, install replacement fuses.

FAQs (Frequently Asked Questions)