1. Intrinsically safe "i" (intrinsically safe electrical equipment and its associated equipment) intrinsically safe circuit:

Under the specified test conditions, the electrical spark and thermal effect generated under normal operation or the specified fault state cannot ignite the circuit of the specified explosive gas or steam.

Intrinsically safe electrical equipment: all circuits are intrinsically safe electrical equipment.

The essential safety components of intrinsically safe devices and associated devices are divided into ia and ib:

¨ ia: Electrical equipment in which normal operation + one fault + any combination of two faults cannot cause ignition.

¨ ib: An intrinsically safe electrical device in normal operation + one that cannot cause ignition under fault conditions.

This shows that the ia level is higher than the ib level

Associated equipment: electrical equipment equipped with intrinsically safe circuit and non-intrinsically safe circuit, and the structure of the non-intrinsically safe circuit cannot adversely affect the intrinsically safe circuit.

2. Flameproof type "d" electrical equipment with flameproof housing.

It can withstand the internal explosion of combustible mixtures that have entered the interior of the housing without damage, and through any joint surface or hole in the housing will not ignite the electrical equipment housing formed by one or more gases or vapors in an external explosive environment.

3. Enhanced safety Type e

4. Oil-filled Type o

5. Sand filling type q

6. Casting type m

Seven. Compound type