A synchronous generator with inertia constant H = 5,text MJ/MVA is rated at 100,text MVA . The angular momentum coefficient M = GH/(pi f_s) used in the swing equation (at 50,text Hz ) is approximately:

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Electrical Engineering QUESTION #2194

Question 1

A synchronous generator with inertia constant $H = 5\,\text{MJ/MVA}$ is rated at $100\,\text{MVA}$. The angular momentum coefficient $M = GH/(\pi f_s)$ used in the swing equation (at $50\,\text{Hz}$) is approximately:

$3.18\,\text{MJ s/rad}$✔️
$5.00\,\text{MJ s/rad}$
$0.318\,\text{MJ s/rad}$
$1.59\,\text{MJ s/rad}$

Correct Answer Explanation

Stored kinetic energy $= H\times S_{rated} = 5\times100 = 500\,\text{MJ}$. Swing equation inertia: $M = \frac{GH}{\pi f_s} = \frac{100\times5}{\pi\times50} = \frac{500}{157.08} \approx 3.18\,\text{MJ·s/rad}$.

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