Creepage Distance(IEC 60815)

Creepage Distance. Creepage is the shortest path between two conductive parts (or between a conductive part and the bounding surface of the equipment) measured along the surface of the insulation.

Clearance Distance. Clearance is the shortest distance between two conductive parts (or between a conductive part and the bounding surface of the equipment) measured through air.

Working Voltages. A working voltage is the highest voltage to which the insulation under consideration is (or can be) subjected when the equipment is operating at its rated voltage under normal use conditions

Tracking that damages the insulating material normally occurs because of one　　　　　　　 or more of the following reasons:

• Humidity in the atmosphere.
• Presence of contamination.
• Corrosive chemicals.
• Altitude at which equipment is to be operated.

Pollution Degrees and Overvoltages

Pollution degree is divided into four categories. The following definitions are based on those in IEC 60664.³

• Pollution degree 1. No pollution or onl　　　　　　　　y dry, nonconductive pollution occurs. The pollution has no influence (example: sealed or potted products).
• Pollution degree 2. Normally onl　　　　　　　　y nonconductive pollution occurs. Occasionally a temporary conductivity caused by condensation must be expected (example: product used in typical office environment).
• Pollution degree 3. Conductive pollution occurs, or dry, nonconductive pollution occurs that becomes conductive due to expected condensation (example: products used in heavy industrial environments that are typically exposed to pollution such as dust).
• Pollution degree 4. Pollution generates persistent conductivity caused, for instance, by conductive dust or by rain or snow.

The overvoltage, also known as installation, category is also divided into four categories according to IEC 60664.

• Overvoltage category I. Signal level (special equipment or parts of equipment), with smaller transient overvoltages than overvoltage category II.
• Overvoltage category II. Local level (appliances and portable equipment), with smaller transient overvoltages than overvoltage category III.
• Overvoltage category III. Distribution level (fixed installations) with smaller transient overvoltages than overvoltage category IV.
• Overvoltage category IV. Primary supply level (overhead lines, cable systems, etc.). This category is not relevant to most product standards.
  
  
  오염된 지역의 전기설비의 연면섬락거리의 선정
  
  IEC 60815 : Guide for the selection of insulators in respect of polluted conditions

1. 공간거리:도체와 도체사이 공간의 최단거리
2. 연면거리:도체와 도체 사이에 설치되어있는 절연재(애자 등,) 표면을 따라 잇는 최단거리.(creepage distance)
3. 절연거리:서로 절연하여야할 부분 상호간의 거리를 말하며 공간거리와 연면거리를 말함.
4. 22900v의 폐쇄 배전반 나도체의 절연거리는
상(R,S,T중)과 대지간의 이격거리:200mm이상.
상과 상의 서로간의 이격거리:215mm이상.
극간(동상 극간):225mm이상.
5. 나도체의 절연거리를 규정한 KEMC, KS, ES, IEC, IEEE, ANSI, NEMA, BS, DIN, VDE, JEM에 의하여
국내 공인기관의 절연성능시험에 합격시 4번의 규정에 의하지 않을 수 있다.