Intrinsically safe circuits should meet the following three basic criteria:
a) According to the protection level and equipment category specified for electrical equipment, when testing or evaluating circuits according to corresponding standard requirements, spark ignition should not occur. When evaluating, data related to voltage, current, and circuit parameters, such as capacitance and inductance at the ignition boundary, are required to assess the circuit as inherently safe from the perspective of spark ignition.
b) The temperature group of intrinsic safety devices should comply with the temperature requirements specified in the relevant standards of GB/T3836 to avoid ignition caused by hot surfaces. The temperature group is not applicable to the associated device. This criterion can be used to calculate or determine the maximum surface temperature of a component based on its known thermal characteristics and the maximum power it may withstand under appropriate fault conditions to meet specified requirements.
c) Intrinsically safe circuits should be fully isolated from other circuits. By specifying sufficient creepage distance and electrical clearance, as well as using reliable components that meet standard requirements (such as transformers and current limiting resistors).
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