What is the isolation circuit inside the transmitter? What is its purpose?

The isolation circuit of the transmitter can effectively prevent strong electromagnetic interference from industrial environments from affecting the sensor circuit. This isolation circuit includes a voltage isolation circuit and a signal isolation circuit; the voltage isolation circuit comprises a voltage sensing circuit, the input of which is connected to the power supply circuit ； An oscillation circuit, whose input terminal is connected to the output terminal of the voltage sensing circuit ； A drive circuit, whose first input terminal is connected to the output terminal of the oscillation circuit, and whose second input terminal is connected to the output terminal of the voltage sensing circuit ； Isolation transformer, whose primary coil is connected to the output terminal of the drive circuit ； A rectifier and voltage regulator circuit, whose input is connected to the secondary coil of that transformer ； The signal isolation circuit includes a digital isolator that connects the sensor circuit and the microprocessor circuit.

Isolation circuits include voltage isolation circuits and signal isolation circuits, which can effectively prevent the interference of strong electromagnetic fields in industrial environments on sensor circuits.

One of the purposes of electrical isolation is to separate noise sources from the parts that are susceptible to interference in terms of circuitry, thereby eliminating interference at the source. The main purpose of circuit isolation is to cut off the paths through which noise interference can propagate by isolating the components, thereby suppressing such noise interference. After implementing circuit isolation measures, the vast majority of circuits can achieve good noise suppression, enabling the equipment to meet electromagnetic compatibility requirements. Circuit isolation mainly includes: isolation of analog circuits, isolation of digital circuits, and isolation between digital and analog circuits. The isolation methods used include: transformer isolation, pulse transformer isolation, relay isolation, optocoupler isolation, DC voltage isolation, linear isolation amplifier isolation, fiber optic isolation, A/D converter isolation, and others.