What is the significance of MIE (with inductance) and MIE (without inductance)? Which one of them is lower?

MIE (without inductance) simulates a purely capacitive electrostatic discharge such as from isolated conductors in an industrial situation. MIE (with inductance) simulates longer duration discharges as the introduction of the inductor into the circuit, delays the spark discharge to earth, hence this corresponds to MECHANICAL SPARK SENSITIVITY.

As the spark duration is shorter for “pure” static electric discharges so the probability of ignition is less than for the MIE (with inductance) and therefore, in many cases the MIE (with inductance) produces a lower value of MIE. A review of your facility will determine whether electrostatic spark discharges or mechanical sparks need to be assessed and the corresponding MIE test performed.