ITU-TK.21客户端电信交换设备耐过电压和过电流的能力.pdf

INTERNATIONAL TELECOMMUNICATION UNION ITU-T K.21 TELECOMMUNICATION (10/2000) STANDARDIZATION SECTOR OF ITU SERIES K: PROTECTION AGAINST INTERFERENCE Resistibility of telecommunication equipment installed in customer premises to overvoltages and overcurrents ITU-T Recommendation K.21 (Formerly CCITT Recommendation) ITU-T Recommendation K.21 Resistibility of telecommunication equipment installed in customer premises to overvoltages and overcurrents Summary This Recommendation specifies resistibility requirements and test procedures for telecommunication equipment which is installed in or on a customer premises building. Overvoltages or overcurrents covered by this Recommendation include surges due to lightning on or near the line plant, short-term induction of alternating voltages from adjacent power lines or railway systems, earth potential rise due to power faults, direct contacts between telecommunication lines and power lines and electrostatic discharges. Source ITU-T Recommendation K.21 was revised by ITU-T Study Group 5 (1997-2000) and approved by the World Telecommunication Standardization Assembly (Montreal, 27 September – 6 October 2000). ITU-T K.21 (10/2000) i FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecom