漏电起痕指数CTI Comparative Tracking Index
漏电起痕指数 CTI/Comparative Tracking Index
CTI是用来描述绝缘材料的电气击穿特性的物理量。
测量方法是： 将0.1%的氯化铵溶液每30s滴1滴到材料（典型厚度为3mm）上，50滴后不产生漏电痕迹的最大电压值就是相对漏电起痕指数。
产生电击穿痕迹的原因是由于足够强的电压差在导体表面产生碳化的路径来使得电流流过。
CTI的数值是用来对电气设备做安全评估的，在电气设备上的高压部分和可被人体触摸部分的最小爬电距离，和CTI值有关。
图中已标出绝缘材料的分类组别和CTI指数之间的关系，I类为最高（IEC 60601-1:2005。)
Comparative Tracking Index
The Comparative Tracking Index or CTI is used to measure the electrical breakdown (tracking) properties of an insulating material. To measure the tracking, 50 drops of 0.1% ammonium chloride solution are dropped on the material, and the voltage measured for a 3 mm thickness is considered representative of the material performance. Also term PTI (Proof Tracking Index) is used: it means voltage at which during testing on five samples the samples pass the test with no failures.
Tracking is an electrical breakdown on the surface of an insulating material. A large voltage difference gradually creates a conductive leakage path across the surface of the material by forming a carbonized track. Testing method is specified in IEC standard 60112.
Performance Level Categories (PLC) were introduced to avoid excessive implied precision and bias.
The CTI value is used for electrical safety assessment of electrical apparatus, as for instance carried out by Underwriters Laboratory in USA and many other laboratories in the world. The minimum required creepage distances over an insulating material between electrically conducting parts in apparatus, especially between parts with a high voltage and parts that can be touched by human users, is dependent on the insulators CTI value. Also for internal distances in an apparatus by maintaining CTI based distances, the risk of fire is reduced.
Tracking Index (V) | PLC |
| 600 and Greater | 0 |
| 400 through 599 | 1 |
| 250 through 399 | 2 |
| 175 through 249 | 3 |
| 100 through 174 | 4 |
| < 100 | 5 |
In design of medical products, the CTI is treated differently. Material groups are classified as shown below, per IEC 60601-1:2005, International Standard published by the International Electrotechnical Commission:
Comparative Tracking Index (CTI) | Material Group |
| 600 <= CTI | I |
| 400 <= CTI < 600 | II |
| 175 <= CTI < 400 | IIIa |
| 100 <= CTI < 175 | IIIb |
CTI値(規格一般用語集)
| 回答 |
| CTI (Comparative Tracking Index) 比較トラッキング指数 ■CTI値の測定方法 (IEC 60112／CTI値、PTI値* の測定方法のA法による) 塩化アンモニウムの0.1％溶液を30sに1滴滴下し、50滴滴下してもトラッキングの起きない最大電圧を CTI値といいます。  * 関連FAQをご参照ください。 ■CTI値による成形材料の区分(IEC 60664-1) 材料グループⅠ CTIが600以上 材料グループⅡ CTIが400以上600未満 材料グループⅢa CTIが175以上400未満 材料グループⅢb CTIが100以上175未満 [関連規格] IEC 60112, IEC 60664-1 |
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标签: 漏电起痕