Fuses are used to protect electrical circuits from overcurrent. The fuse element is made from a material with low melting point and high conductivity to melt and interrupt the circuit when too much current flows. There are different types of fuses like cartridge fuses, liquid fuses, and high voltage fuses used in various applications. An Arc Fault Current Interrupter (AFCI) is a circuit breaker that can detect unintended arcs and disconnect power before a fire starts. It distinguishes between harmless normal arcs and undesirable arcs from issues like a broken cord. The AFCI continuously monitors current and trips only for unwanted arcing to de-energize the circuit and reduce fire risks.

1. Fuses
Principles of Power Systems by V.K.mehta
Chapter 20
Nouman Ahmad
Electrical Engineering Department
University of Engineering and Technology Lahore

2. Electrical fire
• The most inclusive and direct interpretation of “electrical fire” is a fire involving
some type of electrical failure or malfunction. Any equipment powered by
electricity can have such a failure.

3. Fuse
The fuse element is generally made of materials having low
melting point, high conductivity and least deterioration due to
oxidation

4. Fuse Operation

5. Fuse Operating time

6. High Rupturing Capacity (HRC) Fuse

7. (HBC)

8. High Voltage Fuses
(ii) Liquid type.
(i) Cartridge type

9. Arc Fault Current Interrupter (AFCI)
• is a specific circuit breaker designed to help prevent fires by
detecting an unintended electrical arc and disconnecting the power
before the arc starts a fire.
• An AFCI must distinguish between a harmless arc that occurs
incidental to normal operation of switches, plugs and brushed motors
and an undesirable arc that can occur, for example, in a lamp cord
that has a broken conductor in the cord.

10. Arc Fault Current Interrupter (AFCI)
• An AFCI is selective so that normal arcs do not cause it to trip
• The AFCI circuitry continuously monitors the current and
discriminates between normal and unwanted arcing conditions. Once
an unwanted arcing condition is detected, the AFCI opens its internal
contacts, thus de-energizing the circuit and reducing the potential for
a fire to occur