Why is there a Gap in an Arcing Horn?

An arcing horn is provided across an insulator, with a controlled air gap, mainly to protect the insulator from flashover damage.

⚡️ Why the gap is provided

1️⃣ Normal operation:
The voltage is below the breakdown voltage of the air gap, so no arc flows.

2️⃣ During lightning or overvoltage:
The voltage suddenly rises and the air gap breaks down, creating an arc between the horns.

3️⃣ Protects the insulator:
The arc is diverted through the arcing horns instead of passing across the insulator surface.

4️⃣ Prevents permanent damage:
The horns are designed to withstand the arc better than the porcelain/glass/polymer insulation.

5️⃣ Arc movement:
The electromagnetic force and heating make the arc move outward along the horns, helping it extinguish.

✅ Simple principle:
Normal voltage → Gap remains open
Surge voltage → Gap flashes over → Arc flows through horns → Insulator is protected

📌 The gap distance is carefully selected according to the system voltage and required insulation coordination.

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