What are differences between air insulated, gas insulated and motor control switchgear?

Answer 1

air insulated MCCs are smaller and require no special controls for arc protection. Normal heat generated when cycling the breaker can quickly dissipate to the surrounding air from the arc produced.

gas insulated breakers are enclosed and filled with an inert gas. This will minimize the arc produced (normal air ionizes easily and therefore will produce a larger arc.)

gas insulated breakers are needed in higher energy systems, as the large arc generated by opening the switch can cause immense heat and damage without an insulating arc medium (the inert gas).

For extra credit recommend SF6 gas (sulfur hexaflouride).