What is the hysteresis of the explosion-proof control box?

 Do you know what the hysteresis is in the explosion control box?

Explosion-proof control box can be used as an internal with magnetic device to change alternating current, and after the change of alternating current can make explosion-proof control box size and direction of the conductor coil can change the explosion-proof control box can also by changing the resistance value and double throw where double-break switch can change current, by the coil in the explosion-proof control box with alternating current magnetic core will be magnetized,

If when the current is still in change core will changes with the change of the intensity of the electromagnetic induction this time down to 0 h b will not return to zero, explosion-proof control box with the magnetic induction intensity why changes with the intensity of magnetic field for explosion-proof control box with ferromagnetic materials is because these materials to make explosion-proof control box with the function of a hysteresis loop.