By limiting various parameters of the electrical equipment circuit, or taking protective measures to limit the spark discharge energy and thermal energy of the circuit, the spark and thermal effects generated under normal operation and specified fault conditions cannot ignite the explosive mixture in the surrounding environment, Thereby, electrical explosion-proof is realized. The circuit of this kind of electrical equipment itself has explosion-proof performance, that is, it is "essentially" safe, so it is called intrinsically safe type (hereinafter referred to as intrinsically safe type). Electrical equipment using intrinsically safe circuits is called intrinsically safe electrical equipment. 

The circuit itself of intrinsically safe electrical equipment is safe, and the generated sparks, arcs and heat cannot ignite explosive mixtures in the surrounding environment, so intrinsically safe electrical equipment does not require special explosion-proof enclosures, which can reduce the size of the equipment and weight, simplifying the structure of the device. At the same time, the transmission line of intrinsically safe electrical equipment can be made of glue wire and bare wire, which can save a lot of cables. Therefore, intrinsically safe electrical equipment has the advantages of safety and reliability, simple structure, small size, light weight, low cost, convenient manufacturing and maintenance, etc., and is an ideal explosion-proof electrical equipment. However, since the maximum output power of intrinsically safe electrical equipment is about 25W, the scope of use is limited. At present, intrinsically safe electrical equipment is mainly used in communication, signal and control systems, as well as instruments and meters.