Types of fuses

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ELECTROTECHNICS

Types of fuses

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Objective: To identify the types of fuses.

Content:

1.

DC fuses

2.

AC fuses

3.

Cartridge fuses

4.

D-type cartridge fuses

5.

HRC fuses

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Did you know that…

A variety of wire or foil fusible elements

were in use to protect telegraph cables

and lighting installations as early as

1864. A fuse was patented by Thomas

Edison in 1890 as part of his electric

distribution system.

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1. DC fuses

A device whose main function is to protect the

circuit when it is accompanied by a continuous

increase in current. When the current in the

circuit exceeds a certain value, the fuse will be

broken by the heat generated by it, thus the

entire circuit will be disconnected. The internal

structure of the DC fuse is made of metal with

a lower melting point.

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2. AC fuses

Air Conditioning (AC) fuses are a

little bit small in size as compared to

DC fuses as they oscillate at about

50-60

times

every

second

from

minimum to maximum. Because of

this, the chances of arc between the

melted wires is eliminated. Hence,

they can be parked in small sizes.

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3. Cartridge fuses

Used to protect electrical appliances such as

motors, air-conditions, refrigerator, pumps, etc,

where high voltage rating and currents are

required. Are available up to 600A and 600V AC.

There are two types:

1. General purpose fuse with no time delay.

2. Heavy-duty cartridge fuses with time delay.

Both are available in 250V AC to 600V AC

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4. D – type cartridge fuse

They contain an adapter ring, base, cap

and cartridge and is connected to the

fuse cap where the cartridge is inside

the fuse cap. The circuit is completed

when the tip of the cartridge makes

contacts through the fuse link conductor.

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5. High Rupturing Capacity (HRC) fuse

The fuse wire carries a short circuit

current in a set period. If the fault

occurs in the circuit then it blows off. It

is made with glass otherwise some

other kind of chemical compound.

At both sides of the fuse, the ceramic

enclosure is made with a metal cap

which is welded with fusible silver wire.

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6. High Voltage Fuses

High Voltage (HV) fuses are used in

power systems to protect the power

transformer,

distribution

transformers

and instrument transformer where circuit

breakers may not be able to protect the

system. They are rated for more than

1500V and up to 13kV and are generally

made of copper, silver or tin.

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7. Automotive, Blade & Bolted Fuses

Also known as spade or plug-in fuses

come in plastic body and two metal caps

to fit in the socket. Mostly, they are used in

automobiles for wiring and short circuit

protection. Fuse limiters, glass tube (also

known as Bosch fuse) are widely used in

automotive

industries.

The

rating

of

automobile fuses are low as 12V to 42V.

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8. SMD, Chip , Radial, and Lead fuses

SMD (Surface Mount Device) and SMT

(Surface

Mount

Technology)

are

chip

types (also known as electronic fuse)

used in DC power applications like Hard

drive, DVD players, camera, cell phones,

etc. where space plays an important role

because SMD fuses are very tinny in size

and hard to replace as well.

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9. Rewireable Fuses

The kit-kat or rewireable fuse is mostly used in

industries and home electrical wiring for small

current applications in Low Voltage (LV) systems.

Contains 2 basic parts: The inner fuse element as

fuse

carrier

made

of

tinned

copper,

lead

or

aluminum and the base made of porcelain having

the IN and OUT terminals which is used to be in

series with the circuit to protect. Its main advantage

is that can be rewired easily in case it is blown.

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10. Thermal Fuses

Also known as Thermal Cutouts (TCO) or

Thermal Links they are a one time used only

fuse. They are made of temperature sensitive

alloy. The fuse element holds a mechanical

spring contact which is normally closed. When

high currents due to over current and short

circuit flow through the elements of the fuse,

the fuse elements melts down which lead to

release the spring mechanism and prevent fire.

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11. Resettable Fuses

Polymeric positive temperature coefficient device

(PPTC), poly-switch, poly-fuse or resettable fuse

is a passive

electronic

component

used to

protect against short current faults in electronic

circuits. They open the circuit when an over

current event occurs and after some specific

time

they

connect

the

circuit

again.

Its

application

is

to

overcome

where

manually

replacing fuses is difficult or almost impossible.

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Uses and Applications of Fuses

Electrical and Electronic Fuses can be used

in all types of electrical and electronic

systems and applications such as:

Air-conditions

Hard disk drives

Laptops

Power convertors

Cell phones

Game systems

Digital cameras

Portable Electronics

LCD monitors

Printers

Scanners

Battery packs

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Conclusions

A fuse is an electric / electronic or mechanical device, used to protect

circuits from over current, overload and ensure the protection of the circuit.

Electric fuse was invented by Thomas Alva Edison in 1890. Fuse consists of

a low resistance metallic wire enclosed in a non combustible material. It is

used to connect and install in series with a circuit and device which needs to

be protected from short circuit and over current. The working principle is

based on the “Heating effect of Current”. Whenever a short circuit, over

current or mismatched load connection occurs, the thin wire inside the fuse

melts because of the heat generated by the heavy current flowing through it.

Multiple Choice

SMT stands for:

• Support Mount Technology

• Surface Mount Technology

• Surface Mount Technique

Multiple Choice

Also known as kit-kat fuses

• Resettable

• Thermal

• Rewireable

• High Voltage

Multiple Choice

Also known as Poly-switch fuses.

• Resettable

• Thermal

• Rewireable

• High Voltage

Multiple Choice

HV fuse mean:

• High Volume

• High Voltage

• Huge Voltage

• High Volatile

Multiple Choice

Also known as plug-in fuses

• High Voltage

• Thermal

• Rewireable

• Automotive