监控系统以太网保护设计
<p style="margin: 0px 0px 0.58rem; padding: 0px; text-align: justify; color: rgb(60, 60, 61); text-transform: none;31px; text-indent: 0px; letter-spacing: normal; font-family: "PingFang SC", Arial, "微软雅黑", "宋体", simsun, sans-serif; font-size: 0.48rem !important; font-style: normal; font-weight: 400; word-spacing: 0px; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); text-size-adjust: none; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><span style="font-size: 12px;"><strong style="margin: 0px; padding: 0px; font-size: 0.48rem !important;"><span style="margin: 0px; padding: 0px;1; text-size-adjust: none;">以太网保护</span></strong></span></p><p style="margin: 0px 0px 0.58rem; padding: 0px; text-align: justify; color: rgb(60, 60, 61); text-transform: none;31px; text-indent: 0px; letter-spacing: normal; font-family: "PingFang SC", Arial, "微软雅黑", "宋体", simsun, sans-serif; font-size: 0.48rem !important; font-style: normal; font-weight: 400; word-spacing: 0px; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); text-size-adjust: none; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><span style="font-size: 12px;"><span style="margin: 0px; padding: 0px;1; text-size-adjust: none;">以太网电路的保护需要更精致的处理，因为其实现(室内对室外)将决定保护器件所需的稳健性的水平。需要回答的基本问题是，究竟用户是唯一的威胁(考虑ESD)，还是端口也会受到雷击瞬变的影响。对于以太网端口连接到本地路由器或室内摄像机的安装来说，几乎不会有雷电耦合到电路的情况发生，因此ESD将会是唯一威胁。在这种情况下，保护器件的电容值应在4pF左右或更低，因为数据速率大于100Mb/s。</span></span></p>
<p style="margin: 0px 0px 0.58rem; padding: 0px; text-align: justify; color: rgb(60, 60, 61); text-transform: none;31px; text-indent: 0px; letter-spacing: normal; font-family: "PingFang SC", Arial, "微软雅黑", "宋体", simsun, sans-serif; font-size: 0.48rem !important; font-style: normal; font-weight: 400; word-spacing: 0px; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); text-size-adjust: none; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><span style="font-size: 12px;"><span style="margin: 0px; padding: 0px;1; text-size-adjust: none;">对于那些具有长电缆(100m)的、以太网硬件与电气硬件和电路相混合的安装(设备箱)，可以应用GR-1089之类的标准。在这些情况下，建筑物内规范最为重要，它包括对诸如100Base-T的2对接口使用高达100A峰值脉冲电流(对于2/10μs波形)以及对诸如1000Base-T的4对系统的每根电线使用36.4A的峰值脉冲电流(1.2/50μs和8/20μs波形)浪涌的规定。</span></span></p>
<p style="margin: 0px 0px 0.58rem; padding: 0px; text-align: justify; color: rgb(60, 60, 61); text-transform: none;31px; text-indent: 0px; letter-spacing: normal; font-family: "PingFang SC", Arial, "微软雅黑", "宋体", simsun, sans-serif; font-size: 0.48rem !important; font-style: normal; font-weight: 400; word-spacing: 0px; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); text-size-adjust: none; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"></p>
<p style="margin: 0px 0px 0.58rem; padding: 0px; text-align: justify; color: rgb(60, 60, 61); text-transform: none;31px; text-indent: 0px; letter-spacing: normal; font-family: "PingFang SC", Arial, "微软雅黑", "宋体", simsun, sans-serif; font-size: 0.48rem !important; font-style: normal; font-weight: 400; word-spacing: 0px; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); text-size-adjust: none; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><span style="font-size: 12px;"><span style="margin: 0px; padding: 0px;1; text-size-adjust: none;">对于摄像头在户外的以太网安装来说，直接耦合雷击瞬变的可能性非常高。涵盖这一情况的一个标准就是GR1089建筑物间规范。在这种情况下，雷击浪涌定义为具有500A的峰值脉冲电流(对于2/10μs波形)。由于能量极高，需要基于晶闸管的解决方案来进行线路侧保护。对于变压器的物理层侧来说，安装二极管阵列可以“肃清”通过线路侧保护所允许通过的任何能量。</span></span></p>
<p style="margin: 0px 0px 0.58rem; padding: 0px; text-align: justify; color: rgb(60, 60, 61); text-transform: none;31px; text-indent: 0px; letter-spacing: normal; font-family: "PingFang SC", Arial, "微软雅黑", "宋体", simsun, sans-serif; font-size: 0.48rem !important; font-style: normal; font-weight: 400; word-spacing: 0px; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); text-size-adjust: none; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"></p>
<p style="margin: 0px 0px 0.58rem; padding: 0px; text-align: justify; color: rgb(60, 60, 61); text-transform: none;31px; text-indent: 0px; letter-spacing: normal; font-family: "PingFang SC", Arial, "微软雅黑", "宋体", simsun, sans-serif; font-size: 0.48rem !important; font-style: normal; font-weight: 400; word-spacing: 0px; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); text-size-adjust: none; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><span style="font-size: 12px;"><strong style="margin: 0px; padding: 0px; font-size: 0.48rem !important;"><span style="margin: 0px; padding: 0px;1; text-size-adjust: none;">以太网供电</span></strong></span></p>
<p style="margin: 0px 0px 0.58rem; padding: 0px; text-align: justify; color: rgb(60, 60, 61); text-transform: none;31px; text-indent: 0px; letter-spacing: normal; font-family: "PingFang SC", Arial, "微软雅黑", "宋体", simsun, sans-serif; font-size: 0.48rem !important; font-style: normal; font-weight: 400; word-spacing: 0px; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); text-size-adjust: none; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><span style="font-size: 12px;"><span style="margin: 0px; padding: 0px;1; text-size-adjust: none;">如前所述，许多监控摄像头系统能够简易安装的关键之处就是以太网供电(PoE)。正如预期的 那样，这在保护方案里将增加另一个考虑方面—在仅有数据的标准以太网电路中并不存在。也就是说，在应用的两端，以太网线路将连接一个电源。一侧是提供电能 的供电设备(PSE)，另一侧是使用电能的受电设备(PD)，例如IP摄像头。</span></span></p>
<p style="margin: 0px 0px 0.58rem; padding: 0px; text-align: justify; color: rgb(60, 60, 61); text-transform: none;31px; text-indent: 0px; letter-spacing: normal; font-family: "PingFang SC", Arial, "微软雅黑", "宋体", simsun, sans-serif; font-size: 0.48rem !important; font-style: normal; font-weight: 400; word-spacing: 0px; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); text-size-adjust: none; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><span style="font-size: 12px;"><span style="margin: 0px; padding: 0px;1; text-size-adjust: none;">除保护数据线外还要保护电源(PSE或PD)。换句话说，即根据安装类型(只有ESD或浪涌+ESD)保护数据线，同时根据其特有的需要添加电源保护。此外，还需考虑如何实现供电(模式A或模式B)。</span></span></p>
<p style="margin: 0px 0px 0.58rem; padding: 0px; text-align: justify; color: rgb(60, 60, 61); text-transform: none;31px; text-indent: 0px; letter-spacing: normal; font-family: "PingFang SC", Arial, "微软雅黑", "宋体", simsun, sans-serif; font-size: 0.48rem !important; font-style: normal; font-weight: 400; word-spacing: 0px; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); text-size-adjust: none; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><span style="font-size: 12px;"><span style="margin: 0px; padding: 0px;1; text-size-adjust: none;">模式A和模式B实现指的是如何将电源加载到以太网电路或从中移除。对于100Base-T以太网，只使用了可用线对中的两对。另外两对是备用的，未被使用。对于模式APoE，电源将在备用线对上实现。在模式B安装中，电源将在数据线对上实现。最后，应当注意，直流电源信号(高达57Vdc)的方向未指定。它可以被插入到任何一极中。</span></span></p>
<p style="margin: 0px 0px 0.58rem; padding: 0px; text-align: justify; color: rgb(60, 60, 61); text-transform: none;31px; text-indent: 0px; letter-spacing: normal; font-family: "PingFang SC", Arial, "微软雅黑", "宋体", simsun, sans-serif; font-size: 0.48rem !important; font-style: normal; font-weight: 400; word-spacing: 0px; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); text-size-adjust: none; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><span style="font-size: 12px;"><span style="margin: 0px; padding: 0px;1; text-size-adjust: none;">最常见的电源保护方案是横跨输入和电源使用一个双向TVS二极管。选用双向二极管，是为了无论极性如何，都能避开线路电压。</span></span></p>
<p style="margin: 0px 0px 0.58rem; padding: 0px; text-align: justify; color: rgb(60, 60, 61); text-transform: none;31px; text-indent: 0px; letter-spacing: normal; font-family: "PingFang SC", Arial, "微软雅黑", "宋体", simsun, sans-serif; font-size: 0.48rem !important; font-style: normal; font-weight: 400; word-spacing: 0px; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); text-size-adjust: none; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"></p>
<p style="margin: 0px 0px 0.58rem; padding: 0px; text-align: justify; color: rgb(60, 60, 61); text-transform: none;31px; text-indent: 0px; letter-spacing: normal; font-family: "PingFang SC", Arial, "微软雅黑", "宋体", simsun, sans-serif; font-size: 0.48rem !important; font-style: normal; font-weight: 400; word-spacing: 0px; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); text-size-adjust: none; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><span style="font-size: 12px;"><span style="margin: 0px; padding: 0px;1; text-size-adjust: none;">为了确保安防系统元器件和网络功能在整个安装寿命期内都可靠，应当把瞬态保护(ESD和浪涌)考虑进去。在大多数情况下，仅需要基本的ESD保护即可，而暴露在开放室外环境的设备或电缆还应该防范雷击浪涌的威胁。电源电路也会受到瞬态电压事件的影响而需要保护。对于所有这些情况，有大量的解决方案存在，这将使电路板设计人员在设计时更具灵活性。</span></span></p>
<p>你家的防护类东西还行吧</p>
<p>常用</p>
<p>这个设计好像还不够详细</p>
<p>这个设计好像还不够详细</p>
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