Bus Type - Known Parameter - Unknown Parameter Load Bus -P, Q - V, phase angle Generator Bus - P, V (magnitude) - Q, Voltage phase angle Slack Bus Voltage - magnitude and phase angle - P, Q
In this type of tariff, The total charge is divided into two components: fixed charges and running charges. The fixed charges depend upon the number of units consumed by the consumer. It can be expressed as Total Cost = [A (kW) + B (kWh)] Rs. A = charge per kW of max demand (A is a constant which when multiplied with max demand (kW) gives the total fixed costs.) B = charge per kWh of energy consumed (B is a constant which when multiplied with units consumed (kWh), gives total running charges.)
Type B MCB: Type B devices are generally suitable for domestic applications. They are designed to trip at fault currents of 3 - 5 times rated current.
Type C MCB: Type C devices are the normal choice for commercial and industrial applications These devices are designed to trip at 5 - 10 times rated current
Type D MCB: The Type D devices have more limited applications, normally in industrial use where high inrush currents may be expected. Type D devices are designed to trip at 10 - 20 times.