140ACO02000C 模拟量输出模块

140ACO02000C 模拟量输出模块

140ACO02000C 模拟量输出模块

本地系统接地的分离为可能从电气安装的不同部分汲取功率的远程节点。对安装的任何变动（例如在维护工作期间）均可将GPD以至于超出接收器的输入共模范围的程度。因此可能会导致目前正工作的数据链路将来停止运行。 也不建议通过接地线直接连接远程接地，因为直接连接会导致大的接地回路电流作为共模噪声耦合到数据线。 

为实现远程接地的直接连接，RS-485标准建议通过插入电阻器将设备接地与本地系统接地分开。虽然这种方法降低了环路电流，但由于存在一个大接地环路使数据链路对环路其他地方产生的噪声保持敏感。因此，尚未建立稳定的数据链路。 要在强健的RS-485数据链路上远距离承受高达数千伏的GPD，方法是将总线收发器的信号和电源线与其本地信号和电源进行电流隔离。

这种情况下，电源隔离器（例如隔离的DC/DC转换器）和信号隔离器（例如数字电容隔离器）可防止电流在远程系统接地之间流动，并避免产生电流环路。 

140ACO02000C 模拟量输出模块

Local system grounding is separated into remote nodes that may draw power from different parts of the electrical installation. Any change to the installation (e.g. during maintenance work) can increase the GPD beyond the receiver's input common model range. As a result, the currently working data link may stop running in the future. It is also not recommended to connect the remote ground directly through the ground wire, because a direct connection will cause large ground loop current to be coupled to the data line as common mode noise.

To achieve a direct connection to remote ground, the RS-485 standard recommends separating device ground from local system ground by inserting a resistor. Although this approach reduces the loop current, the presence of a large ground loop makes the data link sensitive to noise generated elsewhere in the loop. Therefore, a stable data link has not been established. To withstand GPD up to thousands of volts over long distances over a robust RS-485 data link, the signal and power cord of the bus transceiver is electrically isolated from its local signal and power supply.

In this case, power isolators (such as isolated DC/DC converters) and signal isolators (such as digital capacitor isolators) prevent current from flowing between remote system ground and avoid current loops.