E
electricAl
Any thoughts/suggestions re: this job would be much appreciated, as farm installs aren`t my usual fare. I`ve agreed to help sort it as the farmer`s a bit desperate as he`s got the DNO booked to fit a new pole mounted tranny in not much more than a week!
The entire install is in desperate need of improvement, but like a lot of farmers, he`s put up with it for donkeys - `if it aint broke, don`t fix it`. Now he`s having to accept improvements have to be made - the catalyst being the new tx, brought on by the imminent completion of a new robot dairy.
The existing install consists of the present (40 yr old) dairy, large grainstore, workshops, garages, numerous livestock buildings with truly decrepid light fittings, & 2 domestic dwellings - back to back built (approx 8 beds between em) Most is typically farm bad.
Present TP 70kva supply is overhead to outbuilding loft, approx 80m run. The soon to be installed replacement is underground 140kva supply originating from same pole mount. As to be expected, DNO plan the install of new cut-outs & CT meter on ground floor of same outbuilding & the existing TT arrangement to continue.
Thus far few facts are established at present. As best as i can decypher, the new 24/7 automated dairy will consist of 4 robots, with apparently a 11kva load each + ancillary items such as compressors, brushes & office etc. I hope to have the actual figures verified Monday. Lighting the new 78m x 36m dairy structure is likely to require 24 HQI hi-bays at first guess. An accurate all encompassing load calculation hasn`t yet been done, but a 4c x 70mm SWA already purchased for the 145m sub-main run to new dairy. At least it`ll be big enough
Other than timescale, my immediate concerns are...
The DNO suggestion to farmer that the domestic supplies be incorporated into the new CT Metering - even tho the present arrangement is tap-offs via 3 overhead lines into house(s) & their seperate cutouts/metering (my supposition being the lowest overhead conductor would be `earthed` - so probably TN-C arrangement within the new install )
A 73kva diesel gen-set lives in the adjacent building to the intake
Altho its not been started or serviced for 3+years, farmer wants it incorporating in new arrangement, to avoid down time with his expensive new dairy. Not all that familiar with gen-sets, but doubt ATS or controls will be rated above 100a of original install & certainly not the 200a of new supply. So, with a max output of 100a anyway, it`ll only be able to provide back-up for the new dairy alone.
So, splitting the whole install close to origin would seem necessary, with the dairy the sole recipient of one half of the 200a supply, & everything else on the other. In light of my measuring >0.9a earth leakage for the whole farm, such an arrangement becomes even more attractive. The DNO will undoubtably want to see earth fault protection close up to his CT Meter (altho past experience tells me not to assume anything )
Even a slugged 500mA front ender would be set to spoil the cows milking fun me thinks.
Apologies for such a long post, but kind of a compicated brief. Idea`s to supplement my own gratefully received.
The entire install is in desperate need of improvement, but like a lot of farmers, he`s put up with it for donkeys - `if it aint broke, don`t fix it`. Now he`s having to accept improvements have to be made - the catalyst being the new tx, brought on by the imminent completion of a new robot dairy.
The existing install consists of the present (40 yr old) dairy, large grainstore, workshops, garages, numerous livestock buildings with truly decrepid light fittings, & 2 domestic dwellings - back to back built (approx 8 beds between em) Most is typically farm bad.
Present TP 70kva supply is overhead to outbuilding loft, approx 80m run. The soon to be installed replacement is underground 140kva supply originating from same pole mount. As to be expected, DNO plan the install of new cut-outs & CT meter on ground floor of same outbuilding & the existing TT arrangement to continue.
Thus far few facts are established at present. As best as i can decypher, the new 24/7 automated dairy will consist of 4 robots, with apparently a 11kva load each + ancillary items such as compressors, brushes & office etc. I hope to have the actual figures verified Monday. Lighting the new 78m x 36m dairy structure is likely to require 24 HQI hi-bays at first guess. An accurate all encompassing load calculation hasn`t yet been done, but a 4c x 70mm SWA already purchased for the 145m sub-main run to new dairy. At least it`ll be big enough
Other than timescale, my immediate concerns are...
The DNO suggestion to farmer that the domestic supplies be incorporated into the new CT Metering - even tho the present arrangement is tap-offs via 3 overhead lines into house(s) & their seperate cutouts/metering (my supposition being the lowest overhead conductor would be `earthed` - so probably TN-C arrangement within the new install )
A 73kva diesel gen-set lives in the adjacent building to the intake
Altho its not been started or serviced for 3+years, farmer wants it incorporating in new arrangement, to avoid down time with his expensive new dairy. Not all that familiar with gen-sets, but doubt ATS or controls will be rated above 100a of original install & certainly not the 200a of new supply. So, with a max output of 100a anyway, it`ll only be able to provide back-up for the new dairy alone.
So, splitting the whole install close to origin would seem necessary, with the dairy the sole recipient of one half of the 200a supply, & everything else on the other. In light of my measuring >0.9a earth leakage for the whole farm, such an arrangement becomes even more attractive. The DNO will undoubtably want to see earth fault protection close up to his CT Meter (altho past experience tells me not to assume anything )
Even a slugged 500mA front ender would be set to spoil the cows milking fun me thinks.
Apologies for such a long post, but kind of a compicated brief. Idea`s to supplement my own gratefully received.
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