Cylindrical Fuses

A cylindrical fuse is a type of electrical fuse. Like other types of fuses, it is a safety device used to protect electrical devices from excessive current.

A cylindrical fuse is shaped like a cylinder. It has a thin wire or metal alloy strip in the middle, and two metal caps, one on each end, which are used as contacts when it is inserted (in series) into an electrical circuit. The thin wire is designed to melt at a specific temperature which is reached when the circuit is carrying more than the intended amount of electric current. When the wire melts, the circuit is broken and no electricity flows.

Cylindrical fuses are used in many types of electrical and electronic devices. Not only do they protect the equipment from danger, but they also prevent dangerous fires caused by overheating of circuits. Once a cylindrical fuse has been overheated and the wire has been melted, it no longer functions. After the cause of the excessive current has been remedied, a new fuse must be installed to restore the current through the circuit.

To understand the working principle behind an cylindrical fuse, two critical concepts should be kept in mind:
1. Current flows in a loop
2. Heating effect of current
● Electric current can flow through a conductor only when the circuit formed is complete. If there is a break in the loop, electric charges cannot flow through.
● This is also how switches operate.
● When you put on the light switches at home, the lights come on because you have just completed the circuit allowing charges from the power source to flow through and power your lights.
● When current passes through a conductor, the different electrical components of the circuit like the devices attached or even the wire itself, offer resistance to the current flow.
● The work done to overcome this resistance presents itself in the form of heat.
● This is a simple explanation of the "heating effect" of current.
● The primary use of an electric fuse is to protect electrical equipment from excessive current and to prevent short circuits or mismatched loads.
Cylindrical fuses play the role of miniature circuit breakers.
● Apart from protecting equipment, they are also used as safety measures to prevent any safety hazards to humans.
● The fuse wire in an cylindrical fuse is selected in such a way that it does not face any damage when the normally stipulated amount of current flows through the circuit.
● Under normal conditions, the fuse wire is a part of the circuitry, contributing to a complete loop for charges to flow through it.
● However, when an excessive amount of current flows through the fuse wire, the heating effect of the current causes the fuse wire to melt.
● This is because the fuse wire is chosen such that it has a low melting point.
● This causes the loop to break thereby stopping the flow of charges in the circuit.
● It is important to select a fuse that is properly specified for the circuit in consideration.
● If the fuse that is used is underrated, then it will fail even under normal current conditions, unnecessarily breaking the circuit loop.
● If it is overrated, then it will not break the circuit when required and cause equipment damage and failure and may even present itself as a safety hazard.

A cylindrical fuse is used in older buildings and houses to prevent circuit overloads. This means that the fuse is used to prevent the electrical panel from supplying an excessive amount of current throughout a circuit having defective wiring or appliance and causing a fire. A cylindrical fuse is different than a circuit breaker because it cannot be reset once it trips. Here is how you can test the cylindrical fuses in your electric panel in a few easy steps:
Prepare
Preparation is very important when it comes to testing a cylindrical fuse because you will need to take all necessary precautionary measures to be safe and avoid electrocution. One of the first things you need to do is go to the panel, turn it off completely, and then begin with the testing. Moreover, you need to use only proper tools and materials, as well as protective gear. You should have a pair of fuse pullers with you, which can be found at any local hardware store, or a store with electrical equipment.

Get to know the cylindrical fuse
Before you test the fuse, you need to know what it is about. There are two basic types of cylindrical fuses available, so it all depends on the age and size of the house. Smaller and newer buildings have the cylindrical fuse which has some sensitive links at its ends, wrapped with copper or any other type of conducting material. Older and larger buildings usually have the knife blade fuses. You can check your electric panel at home and see what type of cartridge you have.

Remove the cylindrical fuse
The next thing you need to do is remove the cylindrical fuse from the panel slots. Open the panel and find the cartridge you want to test. Use the fuse puller in the middle part of the cylindrical fuse and pull it out of the slot.

Test the cartridge
The next step is about testing the fuse: Take the fuse you have removed from the slot on a table and use the multimeter, setting it first to continuity, which means that you need to make sure it is set at the lower mark. Once you have the links of the meter on the sides of the fuse, the meter will show zero if the cylindrical fuse works properly.
In the case the fuse is tripped or blown, the meter will read infinite. If the fuse is damaged, you need to replace it, plugging a new one at the slot from where you removed the original one. Always keep in mind that you need to do the replacement of the fuse using the puller, to avoid any injury.