Technical assistance: safety barrier

Input safety barriers are primarily used in conjunction with measuring instruments whose readings need to be displayed in the control room – such as pressure, flow rate, temperature, etc. They serve to transmit signals from the field to the control room. Output safety barriers, on the other hand, are used in situations where the control room needs to send signals back to the field; for example, to control valves, which require signals from the control room to adjust their operation. Other electrical control mechanisms, such as those used for adjusting air vents or regulating current and voltage, also make use of output safety barriers.

Let’s first take a look at the definition of the safety barrier

Safety barriers are generally used in intrinsically safe circuits, with the purpose of blocking certain non-intrinsically safe signals from the control room from reaching the field instruments in hazardous areas. The input/output perspective is considered from the control room; for example, regarding various pressure and temperature signals that the control room needs to receive, an input safety barrier is used ； If it is a control signal and the control room serves as the output, then an output safety barrier is used.

First, we need to understand what a safety barrier is: Safety barriers are generally used in intrinsically safe circuits, with the purpose of blocking certain non-intrinsically safe signals from the control room from reaching the instruments located in hazardous areas. Safety barriers are typically used in environments where high levels of explosion protection are required, that is, in areas prone to fires and explosions. If you feel that a particular area is dangerous, you can use a safety barrier; these include 4-20mA safety barriers and temperature safety barriers. The first type of such barrier comes in both versions with and without power distribution functions.

If you have any doubts, it’s best to ask the manufacturer or do some further research

I’m not sure what kind of application environment LZ is in; I think the question you asked relates to the selection process. Firstly, the main function of a safety barrier is to prevent dangerous energy from safe areas from entering hazardous areas, as well as to control the voltage and current in those hazardous areas. It is divided into two types: Zener gates and isolation gates. Nowadays, isolation gates are the most commonly used. Isolation gates are further divided into two categories: detection-side safety gates and operation-side safety gates. Detection-side safety gates (AI) are used in conjunction with two-wire transmitters such as DCS/PLC, while operation-side safety gates (AO) are used with electrical converters or electrical valve positioners. Some safety barriers at the detection end support the HART protocol; in other words, they are fully compatible with AI/AO functions, thus possessing both input and output capabilities. Therefore, it is still necessary to determine what type of safety barrier to use based on the actual site conditions. I am from Beckhoff Corporation; feel free to contact us if you have any questions.

Thank you to all the sea friends for their help and answers; all my current questions have been resolved

Product Name: Safety Barrier 【Product Description】 During application, certain signals need to be converted (for example, digital/analog signals from the hazardous area must be amplified/isolated in the safe area)； Signal conversion of separate electrode-type level switches ； And converting the voltage divider signals generated by the potentiometers into corresponding current signals, etc., is necessary in order to proceed with further processing; therefore, relevant secondary instruments are required to transform these signals into digital/analog signals that are easier to process. The isolation safety barrier converts/amplifies the digital signals from the hazardous area (NAMUR signals) into relay contact actuation signals, which can directly drive loads or be used as digital signals for input to subsequent processing equipment. It can be used in conjunction with intrinsically safe limit position detection level switches.

You mean the safety barrier at the operating end and the safety barrier at the detection end, right? Well, it depends on whether your energy flows from the hazardous area to the safe area or from the safe area to the hazardous area

It is required whenever connecting intrinsically safe instrument equipment! ! ! The input safety barrier is primarily used to connect the field measurement instruments that enter the control room, such as transmitters and valve position feedback signals ； The output safety barrier is primarily used to connect the actuation mechanism and the control output signals!