Maximum Demand is measured in KVA. All you have to have is Voltage of the system & FL Current. Typically In India MAX demand is measured for 30 minutes. ( If the demand lies at same value for 30 minutes then the max demand is recorded). It need to be calculated with the help of connected load and scheduling of the loads.
But Equipments like transformers we need do this exercise to get the demand that can be loaded on Transformer.
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My equipment load 1500 KVA(Forward) for 10 Minute and -1000 KVA (Regenerative) for 10 minute and 500 KVA (Forward) for 10 Minute so pl tell me what is my maximum Demand?