in free air meaning in English

在自由大气中

Electric cables - calculation of the current rating - thermal resistance - a method for calculating reduction factors for groups of cables in free air , protected from solar radiation
电缆.额定电流的计算.热变电阻.室外避免太阳辐射的电缆组减缩系数的计算方法
Electric cables - calculation of the current rating - part 2 : thermal resistance - section 2 : a method for calculating reduction factors for groups of cables in free air , protected from solar radiation
电缆.额定电流的计算.第2部分:热绝缘电阻.第2节:室外避免阳光照射的电缆组用计算简化系数的方法