$8\mathrm{.}3$ The per$-$unit kVA capability and steady$-$state stability curves at rate minal voltage for a $\backslash (50\backslash$mathrm$\{$MVA$\},13\mathrm{.}2\backslash$mathrm$\{$kV$\},60\backslash$mathrm$\{$~Hz$\}\backslash )$ generator are shown in F P$8\mathrm{.}3.$ The CTs used are $3000$:$5.$ For loss$-$of$-$excitation protection, following:

a$.$ Translate the steady$-$state stability limit to a per$-$unit $\backslash ($ R$-$X $\backslash )$ diagram terminal voltage of $1\mathrm{.}0$ per unit.

b$.$ Translate the $15$ psi capability curve to a per$-$unit $\backslash ($ R$-$X $\backslash )$ diagram for a nal voltage of $1\mathrm{.}0$ per unit.

FIGURE P$8.3$ c$.$ With these limits plotted on an $\backslash ($ R$-$X $\backslash )$ diagram, draw a distance relay offset mho circle to provide protection for low or loss of excitation on this machine.

d$.$ For the relay mho circle selected in part c$,$ determine the per$-$unit offset $($distance of the circle center from the $\backslash ($ R$-$X $\backslash )$ origin$)$ and the per$-$unit circle radius. Translate these values to relay ohms for setting a loss$-$of$-$excitation relay, $\backslash ($ R$=3000\backslash$cdot $5,$ R$=120\backslash ).$