F7115 HIMA

Impedance,EMI,and RFI of long-distance transmission lines make the implementation of voltage control schemes very difficult,in which case current loops are a simple and effective solution.According to Kirchhoff’s law,the current at any point in the current loop is equal to the current at all other points in the loop,which can cancel the effect of transmission line impedance.Spurious pickup of EMI and RFI is minimized due to the low loop impedance and bandwidth(hundreds of ohms,and<100 Hz).PLC systems are useful for proper control,such as factory production systems.

远距离传输线的阻抗、EMI和RFI使得电压控制方案的实施非常困难，这种情况下，电流环不失为简单、有效的解决方案。由基尔霍夫定律可知，电流环中任何一点的电流等于环路中其它所有点的电流，由此可以抵消传输线阻抗的影响。由于环路阻抗和带宽较低（几百欧姆，并且《100Hz），EMI和RFI的杂散拾取被降至最小。PLC系统对于适当的控制非常有用，例如工厂生产系统。