Arc Horn Gap Distance for Transformers – Minimum Air Clearance by Voltage (1–36 kV)

Arc Horn Distance (Clearance Requirements)

Arc horn distance is the minimum air clearance defined to safely control and guide electrical arcs occurring between phases or between phase and ground in high-voltage equipment. These distances are critical for transformer safety, operational reliability, and personnel protection.

Engineering Explanation

• Arc horn distance ensures controlled arc formation and prevents damage to transformer insulation.
• The required spacing depends on voltage level, environmental conditions, altitude, and humidity.
• Insufficient clearance may cause phase-to-phase faults, insulation failure, and safety hazards.
• Outdoor installations must consider pollution degree and moisture exposure.

Application Example

For example, in a 36 kV oil-immersed power transformer, the minimum arc horn distance should be selected as 360 mm. If the transformer is installed at high altitude, this distance should be increased to provide additional safety margin.