Sentence:  The semiconductor also enhances regulation of the charging system, the older dynamo being controlled by two or three relay-like devices: 1. a <WSD>cut-out</WSD> that disconnects the dynamo from the battery when the generated voltage drops below that of the battery, as is the case when the engine is not running. 
Meaning of the word marked with <WSD> tags:  Any of several devices that halts the flow of a current, especially an electric current; a trip-switch or trip.