Q$4.($a$)$ A $1000$ kVA diesel$-$engine generating set was installed on the roof of a $100$ m $-$tall building for $800$ kVA emergency loads. The generating set is connected to an automatic transfer switch in a main LV switchboard on the ground floor, via four $1/$c XLPE cables. The installation information is given, as follows:

Engine: $,$ Perkins $2006$TTAG$2$ with BMEP $=24{10}^2(kPa)$

Alternator: Newage HC$434$F $300$kVA at $380V,1500rpm$

Cables: $4$ no$.$ of $\frac{1}{c}400m{m}^2$ XLPE cables on tray $($flat touching arrangement$)$

With the datasheets provided in Appendix Q$4,$ determine max. real power $($ kW $)$ and total power $($ kVA $)$ the generating set could provide during its starting and normal operations, and estimate the size of the fuel tank assuming $1$ liter of fuel provides approximately $3\mathrm{.}5$ kWh of electrical energy.

You may make any reasonable assumption necessary.

$($b$)$ Describe, with the aid of diagrams, how to classify metalwork found in a building for the purpose of earthing and bonding.

$($c$)$ With the aid of diagrams, $($i$)$ describe the major differences of rolling sphere method and mesh method in designing an air termination network for a building with the height of $100$ m ; and $($ii$)$ given by the roof network in Fig. Q$4$ and datasheets in Appendix Q$4,$ determine, with the justification, whether the roof is protected against lightning using the rolling sphere method and protective angle method, respectively. The class of LPS is assumed to be LPS II$.$