The signal isolator is an instrument that transmits, converts, isolates, distributes, and transmits industrial signals in an automated control system. The isolator can cooperate with various industrial sensors and field instruments to receive various industrial signals such as current, voltage, thermal resistance, thermocouple, switch quantity, etc., and transmit to the user's local monitoring system after isolation, conversion, and transmission.
The principle of the signal isolator: the isolator accepts the output signal of the temperature, pressure or flow of the field instrument once, and then modulates it through semiconductors. After the signal isolation and conversion are carried out through the light sensing or magnetic sensing device, the signal needs to be decoded at the end. The key is converted back to the signal before isolation. At the same time, it is also necessary to isolate the signal power supply after isolation to ensure complete independence of input, power, and output.
Signal isolators are widely used in data acquisition, signal transmission and conversion, PLC, DCS and other industrial measurement and control systems in the fields of machinery, electrical, telecommunications, electricity, petroleum, chemical, steel, sewage treatment, and building construction. The function of the isolator is to protect the control loop of the next level, which not only ensures safety, but also plays a role in signal transmission.
The intrinsic barrier is divided into the detection end and the operation end. The safety barrier can provide working power to the dangerous area, sample the output signal of the transmitter, transform it into a linear signal designated by the user, and output it to the safe area. The safety barrier limits the energy that escapes from the intrinsically safe terminals into the hazardous area, thus ensuring the explosion-proof of the system.
Intrinsic safety barriers often appear in dangerous industries with explosive substances, such as chemical, petroleum, metallurgy, natural gas, and electric power. It is connected with various intrinsically safe instruments and used as the associated equipment of the intrinsically safe explosion-proof system. The principle and function of the safety barrier are similar to that of the isolator, and the "explosion-proof" function is added to the isolator.
Isolators and safety barriers are very important and necessary in industrial safety, just like a "fuse", which guarantees the safety of this circuit. At the same time, the isolators and safety barriers need to use various automation instruments, control systems and actuators to realize the monitoring and control in the industrial production process. Use a signal isolator in each process link to disconnect the process loop without affecting the normal transmission of the process signal, thereby solving the problem of the ground loop.