Surges can cause arcing , and while both phenomena have in common the very rapid rate of damage and rapid breakdown of insulation, the mechanisms and effects are different.

Difference in inflow speed

• Surge damage occurs instantaneously. Lightning strikes, switching events, and high-current interruptions can cause high voltages to be applied within microseconds to milliseconds, destroying insulation instantly.

• Arcing occurs locally in electrical gaps, and once it occurs, it causes a rapid temperature rise (often exceeding several thousand degrees Celsius), which can cause immediate surface insulation damage, short circuits, or fire. While arcing damage is initially localized, repeated arcing can cause significant, cumulative damage throughout the equipment.

Causes and Interrelationships

• Surges can cause arcing. If a sudden, high surge (over voltage) exceeds the insulation's limits, it can induce an arc discharge in the air or on the insulation's surface.

• Example) When lightning strikes or fault current interrupts, the surge causes a sudden increase in potential difference at the contact point or insulation gap, causing the insulation to break down and an arc discharge to occur.

• In circuit breakers, surges and arcs interact repeatedly, such as during switching surges, and the arcs created by the surges can further aggravate the surge damage.

• Conversely, if arcing occurs repeatedly, the insulation limit is lowered due to local deterioration, and if a surge is encountered again in that state, insulation breakdown and arc discharge are easily induced.

• Surges caused by a rise in ground potential can also promote arcing at equipment contact points, which can lead to additional damage such as fire or short circuit within the equipment.

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That is, the surge can be a "direct cause " of the arcing, and the two can influence each other, compounding and aggravating the damage.