A safety barrier is connected between the intrinsic safety circuit and the non intrinsic safety circuit. A device that limits the voltage or current supplied to an inherently safe circuit within a certain safe range. In some special industrial sites such as gas companies and chemical plants, two-wire transmission is not only required to provide power distribution and signal isolation functions, but also to have safety spark explosion-proof performance, reliably restrain power supply power, prevent ignition between power supply, signal and ground, limit current and voltage double limit signals and power circuits, and limit the energy entering hazardous areas within the safety quota range.

As is well known, chemical enterprises belong to high-risk enterprises and are prone to major accidents such as explosions during production and operation. When the following three conditions are met simultaneously on site, an explosion will occur: ① Explosive substances such as explosive gases; ② Oxygen; ③ Explosive source, such as a spark with sufficient energy or a sufficiently high surface temperature of an object. This is the so-called explosion triangle principle

According to the principle of explosion triangle, eliminating any of the above three conditions can prevent explosion. And oxygen is difficult to control, so controlling explosive substances and detonation sources are the two most commonly used methods for explosion prevention. The safety barrier technology is developed based on the principle of controlling the detonation source. The so-called controlled detonation source refers to the artificial elimination of detonation sources, that is, the elimination of sparks that are sufficient for detonation and the elimination of instrument surface temperature rise that is sufficient for detonation. That is, using safety barrier technology, the electrical energy provided to the on-site instruments is limited to neither sparks that are sufficient for detonation nor instrument surface temperature rise that are sufficient for detonation. According to international standards and Chinese national standards, in the event of any malfunction (voltage not exceeding 250 V) of the equipment connected to one side of the safety barrier safety zone, the intrinsic safety explosion-proof method can ensure the explosion-proof safety on site. For instrument detection and control circuits, to ensure on-site safety, it is necessary to limit on-site energy, which means limiting voltage and current. Due to their ability to store and release energy, capacitors and inductors also need to be limited. The commonly used electric energy detonation curves given in international standards and Chinese national standards include voltage current detonation curve, voltage capacitance detonation curve, and current inductance detonation curve. Based on these curves, and considering a safety factor of 1.5 times, people can determine the electrical energy limit parameters for a specified circuit when dealing with a certain type of gas. For example, when dealing with Class IIC gases (such as hydrogen), circuits with a nominal 24 V (DC) power supply (such as transmitters, electrical converters, solenoid valves, etc.) are usually set with a voltage limit value of 28V. Based on this limit value, the voltage current detonation curve is checked, and a safety factor of 1.5 is considered to determine that the current limit value at this time should be 119 mA. The limitation of energy reaching the site can be achieved through safety barriers.
Safety barriers, also known as safety limiters, are an important component of intrinsic safety systems. There are two main types of safety barriers: Zener safety barriers and isolation safety barriers. The core components of a Zener safety barrier are Zener diodes, current limiting resistors, and fast melting wires. Isolation type safety barriers not only have limited energy functions, but also isolation functions. They are mainly composed of circuit energy limiting units, signal and power isolation units, and signal processing units. The main function of a safety barrier is to limit current and voltage, ensuring that the energy available to on-site instruments is within a safe range.

The petrochemical industry is one of the most widely used industries in the field of automation products. In the petrochemical industry, mainstream automation products such as DCS, PLC, control valves, and various field instruments are widely used. However, the connection and safety between various instruments and between instruments and on-site equipment require detailed protective measures. Therefore, in recent years, safety barriers have been widely used in the petrochemical industry. The list of long-term cooperative clients with our company.