Question

A power station consists of two synchronous generators A and B of rating 250 MVA and 500 MVA with inertia 1.6 p.u. and 1.0 p.u., respectively on their own base MVA rating the equivalent p.u. inertia constant for the parallel system on 100 MVA common base is

• A. 2.6
• B. 0.615
• C. 1.625
• D. 9.0

Answer 1

The correct option is D 9.0

$H_A^{{}^{\prime }}=1.6\times \frac{250}{100}=4.0pu$
$H_B^{{}^{\prime }}=1\times \frac{500}{100}=5.0pu$
$H=4.0+5.0=9.0pu$