Intrinsically safe barrier improves workplace safety by limiting the energy available in the process.
Intrinsic safety barrier is the related equipment of explosion-proof instruments and meters, which does not affect the function of the measurement system under normal conditions. It is set on one side of the safe place, and when the intrinsic safe explosion-proof system fails, it can limit the energy (electric energy) entering the dangerous place to the safe value, so as to ensure the safety of the site.
Intrinsically safe barrier is divided into two types: zener diode safety barrier and isolated safety barrier.
1. Zener diode safety barrier
Quick-acting fuse, current limiting resistance or voltage limiting diodes are used in the zener diode safety barrier to limit the input electric energy, so as to ensure the energy output to the dangerous area. Its principle is simple, the circuit is easy to realize, and the price is low, but its reliability in application is greatly affected because of the defect of its own principle, and its application scope is limited.
2. Isolated safety barrier
It adopts a circuit structure that electrically isolates the input, output and power supply from each other, and meets the energy limitation requirements of intrinsic digital input barrier. Compared with Zener security, although it is more expensive, its outstanding advantages in performance bring greater benefits to user applications:
(1) Due to the use of three-party isolation mode, there is no need for system grounding lines, which brings great convenience to the design and on-site construction.
(2) The requirements for instruments in the dangerous area are greatly reduced, and there is no need to use isolated instruments on the spot.
(3) Because the signal circuit does not need to use the common ground, the stability and anti-interference ability of the detection and control loop signal are greatly enhanced, thus the reliability of the whole system is improved.
(4) Isolated safety barrier has stronger input signal processing ability, and can accept and process thermocouple, thermal resistance, frequency and other signals, which zener diode safety barrier can not do.
(5) Isolated safety barrier by CHENZHU, a professional company specializing in safety automation system can output two mutually isolated signals for use by two devices using the same signal source, and ensure that the signals of the two devices do not interfere with each other, and at the same time improve the electrical safety and insulation performance of the connected devices.
Therefore, after comparing the characteristics and performance of zener and isolated safety barrier, we can see that isolated safety barrier has outstanding advantages and more extensive uses. Although its price is slightly higher than that of zener diode safety barrier, its comprehensive cost may be lower than that of zener diode safety barrier in terms of design, construction, installation, debugging and maintenance costs. Almost without exception, isolated safety barrier is used as the main intrinsic safe explosion-proof instrument in the engineering site with higher requirements. Isolated safety barrier has gradually replaced zener diode safety barrier, and has been widely used in the field of safety and explosion protection.