IP防护等级是国际通用的系统，用于对外壳的坚固性进行分类，例如在测量设备上。IP代表“国际保护”。IP 代码总是有两位数字。**个数字表示外壳防止接触或异物进入的程度，第二个数字表示外壳的防水程度。零总是意味着“没有保护”，因此更高的数字意味着更坚固的外壳。

　　原文：

　　IP protection classes are an internationally used system for categorising the ruggedness of housings, e.g. on measuring devices. IP stands for “international protection.” The IP code always has two digits. The first states the degree to which the housing is protected against touch or the ingress of foreign bodies, the second digit denotes the extent to which the housing is waterproof. Zero always means “no protection,” therefore higher digits imply a more rugged housing.