Passive isolator features: Easy to connect self-powered, long-life input and output with misconnection protection, compact, DIN rail mounting, pluggable terminals Application: passive isolator current power parameters can accurately measure speed, the isolation into a standard analog signal output. Instrumentation and Controls (eg PLC), a variety of A / D converter, and is connected with the computer system, widely used in electric power, railway, petrochemical, metallurgy, chemical, food, warehousing and other sectors of automation systems, is a highly cost-effective products. 4-20MA signal input and output, how to select signal isolation? Active or passive use it? Signal isolation channels located between the two systems, so I chose the isolator must first determine the input and output functions, and input and output enable signal isolation mode (voltage-current-loop-powered, etc.) before and after the end of the channel interface mode adaptation . Additionally, there are power precision ﹑ ﹑ ﹑ many important parameters of noise insulation strength ﹑ bus communication functions related to product performance, such as noise and the precision of the power consumption and reliability of heat-related, which requires users to carefully choose. In short, suitable, reliable, cost-effective products are the main principles of selection signal isolators. Therefore Summary: industrial process control systems select isolator principle is: the product should be input - output - power three isolated; isolation method should be electromagnetic isolation; it should be used in accordance with the corresponding location of the instrument interface to elect the required isolation ; when selecting an isolator selection: high-precision, low-power, low temperature drift, low ripple, fast response and miniaturization of the isolator