Demand factor and power factor

Demand coefficient is a crucial data, which directly affects the calculation result of load and the selection of transformer capacity. Especially in some large residential quarters, the selection of demand coefficient is different, and the transformer capacity may differ by one grade or more. The determination of demand coefficient is extremely complicated and experienced. Although there are data available in various existing design manuals, their expressions are vague and there are some unreasonable places. If some manuals stipulate that there are 50 households ~ 100 households, and the demand coefficient is 0.4~0.5, and the demand coefficient above 100 households is below 0.4, assuming that the installed capacity of each household is 6KW, the demand coefficient of 95 households is 0.43, and the demand coefficient of 100 households is 0.4, then the PJS of 95 households is 95 *.

Power factor (PF), also known as power factor, is a unique physical quantity in AC power system. The ratio of the active power consumed by the load to its apparent power [1] is a dimensionless quantity between 0 and 1.

Active power represents the ability of the circuit to do work in a specific time, and apparent power is the product of the effective value of voltage and current. The apparent power of a purely resistive load is equal to the active power, and its power factor is 1. If the load is a linear load composed of inductance, capacitance and resistance, energy may flow back and forth between the load end and the power end, which will reduce the active power. If there are components other than inductance, capacitance and resistance in the load (nonlinear load), the waveform of input current will be distorted and the apparent power will be greater than the active power. The corresponding power factor in these two cases will be less than 1. To some extent, power factor reflects the proportion of generator capacity being used, and it is an important indicator of rational electricity use.