A generator supplying an electrical power given by $$Pe $=2\mathrm{.}5$ sin $6$p$.$u$.$ to

infinite busbar. The input mechanical power drive the generator Prn$=$l p$.$u$.$ If the mechanical drive change from $1$ to $1\mathrm{.}5$ p$.$u$.$ and the load angle increases untilreached maximum value of $60$ find:

i$)$ the equilibrium angle $60$

ii$)$ The energy areas Ai & Az after Pm changes

iii$)$ Is the system stable or not