3500/22-01-01-00表压传感器是通过感受测试介质和大气压力差值输出差分的信号。若传感器透气性不好,使传感器内外存在明显压差,将导致传感器在不同的海拔高度下测试输出有明显差异。
通过低气压试验箱进行透气性试验,在海平面和海拔7 620m 高度下分别进行传感器性能测试,测试结果及对比结果见表1。结果表明从海平面到海拔7 620m传感器输出信号变化较小。说明在从海平面到高海拔过程中,传感器内部气体的大气压力也随着海拔高度的升高而发生改变,只有当传感器内部气体压力与外界环境气体压力相等时,才能使得传感器的表压输出信号不发生改变。实验证明海拔高度升高过程,传感器内部气体可自由出入传感器,因此可证明材料透气性良好。2.2 防水实验
能否隔绝雨水冲击是该类型传感器的重要指标,因此采用IP67 淋雨试验验证其防水性能。
将表压传感器放入喷淋试验箱,然后以450 L/H 喷水量进行喷淋试验,0.5 h 后取出传感器进行测试。试验后,测试传感器性能,结果与喷淋实验前输出数据基本吻合。用绝缘电阻测试仪测试传感器的绝缘电阻为890 MΩ,绝缘性能良好。根据以上测试结果,说明在喷淋过程中和喷淋之后,水未进入传感器,因此可证明材料的防水性能良好3 传感器可靠性设计
传感器的可靠性设计是传感器性能的关键指标。选择合适的防水透气组件所要做的并不单单是从防水透气阀的目录中选择一个产品,而是需要综合考虑产品的材料、尺寸、膜的开孔率、厚度、孔径等多种因素。因此应根据具体的传感器要求(如大透气量、防护等级、工作温度、外壳的尺寸等)进行设计制造。
传感器的防护等级(IP67)表示防水透气组件必须能够承受对水进行防护的量,而周围环境的恶劣程度也会影响防水透气组件在传感器外壳上安装的位置和方法。
在防水透气组件的设计过程中,往往只关注组件的防水性、透气性以及环境适应性,忽略了实际工作条件下传感器的自然凝露带来的问题。如果在传感器设计上没有考虑到防凝露的措施或所采取的措施不当,就会导致传感器内部有水汽凝结在电路板上,导致电路漏电增加或短路,严重时甚至会导致电路烧毁;凝露还可能造成传感器的绝缘性能下降、漏电增大,甚至会出现飞弧和击穿等现象,造成整个系统的损伤。
经过理论分析及大量试验结果表明:安装防水透气组件的压力传感器,内部湿度会跟随外部迅速变化,在凝露情况不可避免的情况下,防水透气组件会迅速排出凝露,将凝露的量控制在比较小的范围不影响传感器性能;而不安装防水透气组件的压力传感器由于凝露的长期累积并不外排会导致电路短路,对压力传感器的可靠性带来巨大风险。RS-422/485 scTew termination includeASCIISerial Port Isolation
2500V RMS port signal solation per UL
The ASCII driver provides a powerful connection between the
1577internal application database in the ProLinx unit and devices
3000V DC min. port 1to ground and port to
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Shipped wih Each Unil
Mini DIN lo DB- 9M serial cables
The serial port on the gateway is userconfigurable to support ASCII
4ft RS 232 configuration cable
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CD (docs and Conliguration uill)ASCII strings). or both.
RS- 4221485 DB-9 to Screw TerminalASCII Specifications
Adaplor (1 or 4, depending on ports)Avilable in up to four port configurations 1o0
ProSoft Configuration Builderreceive and/or transmil data.
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