Question

One main feeder have two sub feeders (Sub Feeder-A and Sub Feeder-B). If the Sub Feeder-A has demand at a time to be 35 kW and Sub Feeder-B has demand at a time as 42 kW, calculate the total individual maximum demand (MD), the demand of the whole system and the diversity factor if the maximum demand of the main feeder is recorded as 70 kW. Explain the possibility of having the main feeder’s MD to be equal with the sum of both sub feeder’s MD.

Answer 1

Maximum demand of main feeder is 70kW. So accordingly maximum demand of the Sub Feeders A B should be (70/2) 35kW. But the individual maximum demand at any time of sub feeder A is 35kW and that of Sub Feeder B is 42kW. Therefore, Total Individual Maximum Demand= 35kW+42kW =77kW

Demand of the whole system (or maximum demand of the whole system)= 70 kW.

Diversity Factor= Sum of Individual Maximum Demand (Maximum demand of the connected or sub feeders in this case)/ Maximum Demand of the whole ssytem ( Maximum demand of the main feeder in this case)

Diversity Factor= 77kW/70kW =1.1

1)If we talk in terms of grid stability or managemnt of peak demand then if diversity factor is 1 , it means at all time the sytem is delivering maximum power or in other words all the feeders are loaded to its maximum capacity. in such a scenario it will be difficult to manage the sytem if there is any sudden spike in demand may be for a few minutes only as the feeders are already loaded to its maximum capacity.

2) We try to achieve 100% load factor for a system, it means ratio of average load to maximum load of any sytem should be maximum. In order to achieve this we need to lower the maximum demand of the system or maximum demand of individual load should be at different time so that the power usage or power demand is almost constant throughout the day. This can happen only when Individual maximum demand of the system is low. If this is low then automatically diversity factor will be more than 1.