Siemens DTU3005-B Especificaciones descargar pdf (Pagina 32)

Power Factor Problems It can be seen that an increase in reactive power causes a

corresponding decrease in power factor. This means the power

distribution system is operating less efficiently because not all

current is performing work. For example, a 50 kW load with a

power factor of 1 (reactive power = 0) could be supplied by a

transformer rated for 50 kVA. However, if power factor is 0.7

(70%) the transformer must also supply additional power for the

reactive load. In this example a larger transformer capable of

supplying 71.43 kVA (50 ÷ 70%) would be required. In addition,

the size of the conductors would have to be increased, adding

significant equipment cost.

The Cost of Power Utility companies sell electrical power based on the amount of

true power measured in watts (W). However, we have learned

that in AC circuits not all power used is true power. The utility

company must also supply apparent power measured in volt-

amps (VA). Typically utilities charge additional fees for increased

apparent power due to poor power factor.

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Siemens DTU3005-B Especificaciones Pagina 32