neutral connection and ground

it may sound like a below standard question but, i got confused in my 3rd sem training project on that.

can some one tell me how to originate a neutral connection in DCS. i have seen all neutral connected to a single point but where this single point is connected to? isn't neutral is same as ground? then why we use to seperate connections?

thanx for your time and suggestion

Just consider current flow equivalent to stream of water. For water to flow there should not be a break in path. The current originates at +ve terminal or phase passes through your devices connected in the circuit and ends at neutral or negative. Yes, in most of the DCS circuits all the neutrals are connected common. From that common, one line connects to your main power supply to complete the path. If you study your circuit carefully your fundas will get clear.

Regarding grounding of neutral, you have to consult your DCS vendor coz many vendors need floating supply.