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Linear Heat Detection (LHD) (also known as ''Linear Detection Wire'' or ''Linear Heat'') is a very commonly used method of fire detection. It can detect a fire any where along the length of the cable, and can be of lengths in excess of a kilometer. Applications can range from building fire alarm systems to mobile plant machinery. == Operation == Linear Heat Detection (LHD) cable is essentially a two-core cable terminated by an end-of-line resistor (resistance varies with application). The two cores are separated by a polymer plastic, that is designed to melt at a specific temperature (commonly 68°C for building applications〔(【引用サイトリンク】url=https://www.tyco-fire.com/TFP_common/TFBP_LHD_Slick.pdf )〕), and without which causes the two cores to short. This can be seen as a change in resistance in the wire. There are a limited states the LHD cable can be in: # Open-circuit - Effectively an infinite resistance # Normal Operating Condition - Apparent resistance will be the same as the end-of-line resistor # Fire Detection - Resistance of the Linear Heat Cable to the short circuit 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Linear Heat Detection」の詳細全文を読む スポンサード リンク
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