Question

A three phase full converter delivers a ripple free load current of $10A$ with a firing angle delay of ${45}^o$. If the input voltage is $440V,50Hz$ then, the reactive power input is

• A. $2.6kVAR$
• B. $4.2kVAR$
• C. $3.8kVAR$
• D. $4.6kVAR$

Answer 1

The correct option is C $3.8kVAR$

Reactive power input of a three phase full converter
$Q_i=V_0{I}_{0}tan\alpha$
$V_0=\frac{3V_{mL}}{\pi }cos\alpha =\frac{3\times \sqrt{2}\times 400}{\pi }\times cos{45}^o={381.97}^{o}V$
$Q_i=V_0{I}_{0}tan\alpha =381.97\times 10\times tan{45}^o$
$=3819.7VAR\approx 3.82kVAR$