Air insulated means the substation is in the open air, and the dielectric strength of the air is used to isolate conductors from each other and from ground. Gas insulated means a specific gas is used for insulation; this gas is usually an inert gas such as nitrogen. Gas insulated substations, by definition, are required to be inside a contained structure, or large piping must be placed around all conductors to hold the gas.
This seems like a question from an electrical course, and is probably best answered by your course materials. It's your test question, not ours, and there won't always be someone to ask for the answer. Earn your diploma.
water distribution system ===
What is the difference between rated capacity and the nominal capacity
'One stores food and the other keeps your house cool!
It is something like the difference between ship, car and air-plane: they are hardly similar in any aspect.
Air insulated substation means air acts as the dielectric medium but in case of gas insulated substation SF6 is the dielectric medium. Gas insulated substations are having more advantages than air insulated substations.
This seems like a question from an electrical course, and is probably best answered by your course materials. It's your test question, not ours, and there won't always be someone to ask for the answer. Earn your diploma.
insulated cookie sheets hold the heat from the oven longer than an air bake cookie sheet
An insulated cookie sheet is made from two thin sheets of metal with an air space in between.
the difference between dry air and atmospheric air is that atmospheric air contains water vapor but dry air contains no water vapor
difference between laminar air flow & reverse laminar air flow
difference between air jet loom and water jet loom
the difference between inhale and exhale is when you inhale you get more oxygenthan you exhale
differece between water and air transportation
A sporter air rifle and what?
the answer is atmosphere and trosphere
Air in the H (high) pressure system is denser and sinks, leading to stable weather conditions with clear skies. In contrast, air in the L (low) pressure system is lighter and rises, leading to unstable weather conditions with clouds, precipitation, and potentially storms.