Intrinsically safe telephone
    5.
    发明授权
    Intrinsically safe telephone 失效
    本质安全电话

    公开(公告)号:US5136630A

    公开(公告)日:1992-08-04

    申请号:US553538

    申请日:1990-07-13

    摘要: An intrinsically safe telephone as provided for use in hazardous areas. The telephone includes a single line instrument located in the hazardous area which, in turn, is coupled by a two-wire transmission path to a shunt diode barrier and a telephone line interface located in a safe environment. The telephone line interface reduces power of incoming ringing and audio signals. The telephone line interface further includes an off-hook indicating circuit which senses when the single line instrument is off-hook. The intrinsically safe telephone is useful in all hazardous environments as classified by the National Electrical Code and requires no explosion-proof housing.

    摘要翻译: 一种本身安全的电话,用于危险区域。 该电话包括位于危险区域中的单线仪器,该单一线路仪器又通过双线传输路径耦合到并联二极管屏障和位于安全环境中的电话线接口。 电话线路接口可降低输入振铃和音频信号的功率。 电话线接口还包括一个摘机指示电路,它检测单线乐器何时摘机。 本安电话在所有危险环境中都有用,按“国家电气规范”分类,不需要防爆外壳。