无源晶振自身无法震荡，在工作时需要搭配外围电路。在一定条件下，石英晶片会产生压电效应：晶片两端的电场与机械形变会互相转化。当外加交变电压的频率与晶片的固有频率相等时，晶体产生的振动和电场强度，这称为压电谐振，类似与LC回路的谐振。图1石英晶体的电路符号、等效电路、电抗特性及外围电路图由于晶体为无源器件，其对外围电路的参数较为敏感，尤其为负载电容。根据晶体的手册，我们得知测试电路中有电容，此电容对晶体是否起振大有关联：CCg称作匹配电容，是接在晶振的两个脚上的对地电容，其作用就是调节负载电容使其与晶振的要求相一致，需要注意的是CCg串联后的电容值才是有效的负载电容部分。
PV032R1K1T1NGLC
PV032R1K4T1NFHS
PV032R1K8S1NFWS
PV032R1K8T1NMMC
PV032R1K1T1WFDS
PV032R1K1AYNMTP
PV032R1K1T1NHCC
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PV040R1K1T1NHCC
PV040R1K1T1NMF1
PV040R1K1JHNMMC
PV040L1K1T1NMMC
PV040R1K1S1NFWS
PV040R1L1T1NMMC
PV040R1D8T1N001
PV040R1K1T1NMFC
而我国电网系统基础设施维护完善，供电可靠率达99.9%。在变电站设置监测站点并通过电网已有通讯系统开展预警系统通讯，具备实现高可靠性的有利条件。更为重要的是，智能电表的普及为电网地震预警系统服务民众提供了便捷终端，能更充分发挥预警系统的社会价值。智能电表作为预警终端，不仅可以发出声光报警信息，还可以实现预警信号与应急操作的联动。，预警信号到达时，智能电表输出的控制指令可以让正在运行的电梯在就近安全位置自动停靠，防止人员被困电梯内；可以让小区燃气自动切断，防止震后火灾发生；可以让振动敏感的生产线自动“刹车”，防止关键设备受损和产品报废，等等。
PV040R1K1T1NFWS
PV040R1K1T1WFR1
PV040R1K1T1NKLC
PV040R9K1T1NFWS
PV040R1K1T1NFFC
PV040R1K1T1NF
PV040R1K1T1N100
PV040R1K1T1WMR1
PV040R1K1T1NFRZ
PV040R1K1T1WMRC
PV040R1K1T1NMMK
PV040R1K1T1NMMC
PV040R1K1T1VMMC
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PV040R1K1T1NELA
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PV046R1K1T1N001
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PV046R1K1T1NFDS
PV046R1K1T1NFR1
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PV046R1K1T1NMFC
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PV046R1K4T1NFHS
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PV046R1K1S1NFWS
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PV046R1K1T1NHCC
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PV046R1K1T1NGLC
PV046R1L1T1NMMC
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PV046R1K1T1NMMCX5934
PV063R1K1T1NMF1
PV063R1K1T1NMMC
PV063R1K1T1NMMK
PV063R9L1TNMPCK0
PV063R1K1A1VFPR
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PV063R2K1T1N001
PV063R9L1T1NFWS
PV063R1K1A1NFHS
PV063R1K1T1NFFP
PV063R1K1T1NFPR
PV063R1K1T1NGLC
PV063R1K1T1N001
PV063R1K1T1N100
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第三级别主要由供电模块自身硬件电路完成。2接驳盒节点电量测量模块观测网络电源模块提供的电压是标准的5V、12V、24V，即整个监控系统的输出电压范围为5V~12V，可以利用电量隔离传感器进行电压的隔离和变换，取得与被测电压成正比的0~5V信号电压，经过A/D转换由采集模块接收，然后通过传输模块传送给监控中心。观测网络电能管理系统中，采用直流供电技术进行对接驳盒内部各种设备的供电。为了实现采集信号和低压数据采集系统的完全隔离，提高系统的抗干扰能力和可靠性，系统采用WBV121G07电压隔离传感器进行供电设备直流电压的检测，该电压隔离传感器采用线性光电隔离原理，对电压信号进行实时测量，经隔离转换成跟踪输入信号的、有一定隔离能力的标准跟踪电压。
