Explosive gas environment: atmospheric conditions, gas, vapour or mist of combustible substances and air mixtures, lit in the mixture, combustion environment will spread to the entire unburned mixture.
Working temperature: device at rated operating time temperature achieved. Maximum surface temperature: electrical equipment allowed when running under the most adverse conditions, the surface or may reach any part of may the maximum temperature of the surrounding explosive atmosphere.
Explosion-proof type: in order to prevent electrical equipment ignited the explosive gas environment around specific measures to be taken.
Intrinsically safe circuits: in normal operation and under fault conditions any spark or any thermal effect cannot ignite, explosive gas environment of the circuit.
Intrinsically safe equipment: all circuits are intrinsically safe circuits within electrical equipment.
Flameproof enclosure: a kind of explosion-proof type electrical equipment, with a shell capable of withstanding any shell combined with surface or the structure penetrate the gap to inside the housing of the flammable mixture in an internal explosion without damage, and not the external one, gases or vapors form explosive atmospheres lit. Flameproof enclosure explosion-proof type commonly referred to as explosion-proof, the letter "d". Symbol Ex shows that the electrical apparatus complies with one or more of the provisions of the explosion-proof type.
Second, category and temperature class:
Electrical apparatus for explosive gas atmospheres are divided into:
Category I: electrical equipment for coal mining,
Category II: other than coal mine electrical apparatus for explosive gas atmospheres.
II electrical equipment can be further classified according to the characteristics of explosive gases:
II class across burst type "d" and nature security type "I" electrical equipment and is divided into IIA, and IIB, and IIC class; this classification for across burst type electrical equipment by maximum test security clearance, for nature security type electrical equipment by most foreword so current divided; logo IIB of equipment can applies Yu IIA equipment of using conditions, logo IIC of equipment can applies Yu IIA and the IIB equipment of using conditions.
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