Calculation of Electrical Maximum Demand (Contract Demand)

Abstract:

The Electricity provider does charge the fixed charges on the basis of consumer’s maximum Electrical Demand.  Consumer shall restrict the power consumption under the contracted maximum demand. This article furnishes calculation for Maximum Contract Demand.

1. Introduction:

The Electricity provider does record maximum demand in pre-defined interval (e.g. 30 minutes or 15 minutes) through duly sealed and calibrated energy meter. Generally Maximum Demand denotes in kVA for billing purpose.  

Consumer need to sanction Maximum demand from Electricity Provider considering type of industry and operation pattern of the equipments.  Consumer shall pay fixed charges on the basis of Maximum Demand obtained from the provider i.e. the maximum rate at which an electrical power has been consumed during any period of defined consecutive minutes in the billing month.

2. Analysis:

General Formula to calculate the Maximum Demand is described below:

Maximum Demand= Connected Load * Load Factor / Power Factor.

Where,

Connected Load = Total Connected load in the facility in kW.

Load Factor = Utility Factor * Diversity Factor.

Power Factor = System average Power Factor.

Example:

Total connected load of facility: 6500 kW

Load Factor: 0.4 (Considering steel plant type)

Power Factor: 0.95

Maximum Demand= 6500 * 0.4 / 0.95

                          = 2737 kVA

Utility Factor and Diversity Factor can be finding out by the Time Profile of load and usage of the equipment. All equipments of facility may not operate at similar time and also may not run with full load.

Hence, Diversity Factor in percentage = Installed load / running load.

3. Conclusion:

Consumer should sanction Maximum Demand after studying the load pattern of the electrical installation. Obtaining higher Maximum Demand shall result higher minimum fixed charges plus higher deposit, and if sanctioned Maximum Demand exceed than consumer shall confront penalty.