This document discusses arc phenomenon in circuit breakers. It describes that an arc occurs when contacts open during a short circuit, as the potential difference maintains ionized particles between contacts. There are two main methods to extinguish the arc: high resistance, by lengthening/cooling the arc to increase resistance; and low resistance, by recombining or sweeping away ionized particles to reduce conductivity. The key factors in arc extinction are potential difference, ionization level, and separation distance of contacts during opening.

1. ARC PHENOMENON IN CIRCUIT BREAKERS
EEE 427 – Power System Protection
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2. Susmita Debnath
ID: 183001028
Jannatul Ferdous
ID: 183001013
Ashikul Rahman Shipon
ID: 183001068
Mutasim Billah Tahsiin
ID: 183001053
Yamin
ID: 183001027
Badhon Kumar Biswas
ID: 183001005
Meet Our Team
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3. CONTENT
 Circuit Breaker
 Circuit Breaker Operating Principle
 Arc Phenomenon
 Arcing Period
 The Arc Resistance
 Principles of Arc Extinction
 Methods of Arc Extinction
 Conclusion
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4. Circuit Breaker
• A circuit breaker is a piece of equipment
which can –
i. Make or break a circuit either
manually or by remote control under
normal conditions
ii. Break a circuit automatically under
fault conditions
iii. Make a circuit either manually or by
remote control under fault
conditions
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5. Circuit Breaker Operating Principle
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6. Arc Phenomenon
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When a short-circuit occurs, a heavy current flows through the contacts of the
circuit breaker before they are opened by the protective system

7. Why Arc Happens?
• The potential variation that
exists between contacts
• Ionized particles those are in
between contacts
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8. Arcing Period
The time at which the electric arc burns at the contacts of the
circuit breaker during its opening.
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9. The Arc Resistance
• Degree of ionization
• Length of the arc
• Cross-section of arc
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Arc resistance is defined as the ability of an insulating material to withstand a high
voltage electric arc and resist the formation of a conducting path along its surface.

10. Principles of Arc Extinction
i. Potential difference between the contacts
ii. Ionized particles between contacts
(i) When the contacts have a small separation, the potential difference.
between them is sufficient to maintain the arc. One way to extinguish the arc is to
separate the contacts to such a distance that p.m. becomes inadequate to maintain the
arc. However, this method is impracticable in high voltage system where a separation
of many meters may be required.
(ii) The ionized particles between the contacts tend to maintain the arc. If the
arc path is deionized, the arc extinction will be facilitated. This may be achieved by
cooling the arc or by bodily removing the ionized particles from the space between the
contacts.
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Methods of Arc
Extinction
High resistance
method
Low resistance or
Current zero
method

12. High Resistance Method
The resistance of the arc may be increased
by :
(i) Lengthening the arc
(ii) Cooling the arc
(iii) Reducing X-section of the arc
(iv) Splitting the arc
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13. Low Resistance Or Current Zero Method
(a) Causing the ionised particles in the space between contacts to recombine into
neutral molecules.
(b) Sweeping the ionised particles away and replacing them by un-ionised particles
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(i) Lengthening of the gap.
(ii) High pressure.
(iii) Cooling.
(iv) Blast effect.

14. Important Terms
• Arc Voltage
• Restriking Voltage
• Recovery Voltage
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