The first electrical fuse was patented by Thomas Edison in 1890 as a crucial component in the delivery of electricity.
Just about everything that uses electricity requires a fuse to protect it from overloads and short circuits.
Not all systems use the same kinds of electrical fuses. Each has unique needs, which has brought about the invention of many different types of fuses.
Keep Reading for more.
Electrical Fuses for DC Circuits
DC circuits typically run on lower voltages and amperages than AC circuits.
The applications of DC power are many. The following are the most common fuses used in DC systems:
These types of fuses look like little glass tubes with metal caps on each end with a filament inside.
The size of the filament determines the voltage and amperage maximum the fuse can handle
These electrical fuses consist of two blades with a filament between them, which are both secured in a plastic casing.
The size of the filament and the color of the casing designate its amperage and voltage application.
These fuses are also used in solar arrays and battery charging systems and are often arranged in groups, such as a Riedon fuse block.
These contain carbon black particles mixed in with organic polymers.
Enough carbon exists to allow conduction across them. When too much amperage flows through the mixture, creating heat, the polymer expands, creating distance between the carbon particles and interrupting conduction.
When they cool the fuse resets.
These fuses are the choice with sensitive equipment and they sit between diodes, thyristors, etc., on a PCB.
Their ultrafast response protects PCBs consisting of sensitive components that suffer damage from even minor current spikes.
Some devices require voltage spike protection as well.
NTC type fuses act by decreasing resistance in response to voltage spikes and absorbing excess electricity.
High Voltage Electrical Fuses for AC Circuits
AC fuses differ depending upon the voltage and amperage they are designed to handle.
These high voltage fuses are robust and more complex than lower voltage fuses:
High Rupture Current (HRC) Fuses
These are constructed with a non-conductive, high-heat exterior.
The cavity is filled with silica or quartz as an energy dissipator.
The metal caps are affixed to the body with an airtight seal to contain energy overloads.
The filament is typically made of silver of a thickness that will melt at a particular temperature.
You see these types of fuses on overhead power lines. They are designed to protect transformers.
These are typically filled with boric acid that produces an expanding gas when heated during a current overload.
The gases extinguish the electrical arc and then get expelled through one end of the fuse.
These also exist in a drop-out construction where the fuse swings out from the circuit it protects.
Low Voltage Electrical Fuses for AC Circuits
Low voltage AC circuits sometimes use cartridge fuses that appear and operate similarly to DC cartridge fuses.
Drop-out fuses that are typically used in high-voltage applications are sometimes used in low-voltage applications.
Striker fuses appear on electric motors such as garbage disposals. A spring-loaded striker pops out when the system is overloaded. You re-engage it by pushing the striker back into position.
A Fuse for Every System
Whether for protecting a diode on a circuit board, or a high-voltage line serving a neighbourhood, the fuse keeps electrical systems safe.
Without electrical fuses our electrical systems would fail, causing damage to devices, fire, plus costly and time-consuming repairs.
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