The air path differs from the insulating-surface path
- Clearance
Measure the relevant shortest air distance between conductive parts. Do not substitute a longer route along the insulating surface.
- Creepage distanceThis term
Follow the relevant insulating surface between conductive parts. Ribs, material and contamination influence the applicable assessment.
- Insulation coordination
Match clearance, creepage and solid insulation to the expected stresses and environment. A voltage label alone does not define the complete design.
- Partial discharge (PD)
A discharge can occur within a void or another local stressed region without fully bridging the insulation. Assess the actual insulation system and test method.
Clearance crosses air, while creepage follows the insulating surface. Insulation coordination also considers solid insulation and electrical stress; a local discharge may only partly bridge the insulation.
Conceptual distances and exaggerated defects without design dimensions. Required distances and tests depend on voltage, overvoltage, pollution, material, altitude and the actual interface.