线路继电器 meaning in English

line relay

Specification for alternating - current line relays double - element 3 - position for railway signalling
铁路信号用3位置双元交流线路继电器规范
Specification for tractive armature direct current neutral - polar line relays for railway signalling
铁路信号用牵引电枢直流中性极化线路继电器规范
Specification for tractive armature direct current neutral track and line relays for railway signalling
铁路信号用牵引电枢直流中性线拨轨继电器和线路继电器规范