Instrument symbol
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Dear experts, what are the electrical symbols for isolators and safety barriers? The English term is SB, but isn’t this a button?
Isolators and safety barriers have no graphic symbols, but are represented by textual codes. For example, in a temperature control system, the safety function can be denoted as TN—***; the input safety barrier is represented by TN—***A, while the output safety barrier is represented by TN—***B. Here, the letter N is a custom-defined letter.
*IB. *OB * denotes the control quantity. i and o stand for in and out respectively. For example, LIB TIB. POB refer to the input safety gate of the liquid control circuit, the input safety gate of the temperature control circuit, and the output safety gate of the pressure control circuit, respectively.
N is commonly represented in the industry as a surge protector. Terms such as tin and lon refer respectively to the input surge protectors for temperature instruments and the output surge protectors for level instruments