DG Set for residential purpose-70kva

Primarily it's depends on rating of DG set & availability of water for cooling tower use.

Rating of DG set is 70KVA only so its advisable to go for air cooled.

No. of earth pits required are normally varies as per local authority. In general 2 nos. for neutral & 2 nos. body & 1 no. for panel board. ( panel board & body earthing can be combined to form a grid to reduce earth resistance value.) Distance between the earthing should be twice the length of earth rod, normally 3-5m. If ground resistivity is less (soft soil ) then u can ue plate earthing. If it's a hard rock strata then pipe earthing (boring ) is advisable. Location of the earth pit should be outside the DG set canopy or DG room. If DG room is not yet constructed then it can be done near the foundation of DG set.

AMF panel location should be near to the DG set.

You can refer DG manual for the lifting precautions.

70 kVa is huge for a residence. Bloody huge. You must have 500 m2 residence with ACs going 24/7 in Qatar !!!! Be careful of correct size. Small diesel engines MUST remain loaded at least 35% (preferably 50%) or they have problems with unburned diesel fuel dilution of the lube oil and carbon in exhaust components. It is better to run a diesel at 80%-90% load than at 20% load.

Use a 1500 RPM (50 Hz) or 1800 RPM (60Hz) unit for noise reduction. If you get a 3000 RPM (50 Hz) or 3600 RPM (60 Hz) or will be VERY noisy. 1000 RPM is best but quite difficult in such a very small unit.

Take care for altitude and ambient temperature de-rating. This machine will de-rate 3% for each 300 m above the first 200 m altitude. If in desert, the temperature will de-rate output of engine and generator as generator (alternator) is cooled by air. I also recommend air cooled. Deutz is best air cooled gen set .... period !! They know all conditions arctic, desert, altitude, etc. http://www.deutz.de/live_deutz_com/html/default/ssod-6x5c8y

Take care for cold temperature and diesel fuel forming wax. Do not mount sensitive electrical panels on the vibrating machine.

Put machine on concrete that is 3 x 4 weight of machine and on spring isolators between machine and concrete to avoid vibration transfer to structures. If it goes on a roof, build a steel 'box' that can hold 4 x concrete weight of machine, pour the steel box full of concrete, mount unit to top of concrete, then, mount the entire 'block' on springs. The gen set and concrete must be 'one', then springs isolate the mass from the roof structure to prevent vibration annoyance.