平滑时限特性距离保护装置 stepped curve distance time protection: 阶梯时限特性距离保护装置stepped curve distance-time protection: 阶梯时限特性距离保护装置distance time curve: 距离时间曲线distance-time curve: 距离-时间曲线time distance curve: 时距曲线下载手机词典可随时随地查词查翻译