Maximum Demand

Of what?????????????????

Of an electrical system? Easy. Measure it.

In any company, when it takes service connections from electricity authority, it agrees at some contract demand. This contract demand should not be exceeded during a billing period. Now this demand is an integrated value of demands within a specified period like 30 min/15 min or so. Not an instanteneous value. For example , if we say some x company has its contract demand of 30MVA, then it means that its demand limit is 30MVA*30Min=900 MVA Min.

Now if the demand is 10 MVA for first 10 min and then 20 MVA for next 20 min, then Maximum Demand calculation=(10MVA*10Min)+(20MVA*20Min)

=100+400=500 MVA min

So, ur MD=500MVA Min/30 Min=16.66MVA

Existing system means take peak demand achieved last one year readings.

Estimation means Total Connected load *demand factor=Max.demand