[Amps] Tuned power transformer

[Ian White, G3SEK]

Angel Vilaseca wrote:
>
>What is a power factor correction? What is its purpose?
>
Viewed from the mains, the power supply typically looks like a load 
resistance in parallel with the inductance of the transformer. This 
means the load on the mains is somewhat reactive (inductive), so the 
voltage and current are not quite in phase.

Power factor is the cosine of the phase angle between V and I, and it 
ranges from 1 (purely resistive load) to 0 (purely reactive).

Even though reactive currents do not actually deliver useful power, it 
still costs the power company money to generate them. Therefore they 
charge extra to industrial electricity users if their load power factor 
is not close to 1. To save on their bills, industrial users often 
correct their power factor by connecting a component of the opposite 
reactance in parallel with their load.

Because the transformer primary is inductive, the parallel correction is 
a capacitor.

As well as saving money, power factor correction is good practice. 
However, it is unusual to see PFC used in a power supply as small as the 
one you are describing.


-- 
73 from Ian G3SEK
http://www.ifwtech.co.uk/g3sek