Gents,
Best practice would suggest that a DG Neutral Earthing Breaker would be sized as the Phase circuit breaker but is this really necessary given the low neutral current which will flow in service ?
Are there any factors which would justify derating the device and what might be a sensible...
Hello,
I am designing a power system which comprises a 11/0.4kV 1000kVA grid connected transformer feeding an LV switchboard. In addition a 1000kVA generator will be used in parallel with the transformer for occaisional peak lopping (TRIAD operation). To meet the requirements of G59 and in...
Hello,
I work in the water industry where the standard earth nest resistance for an LV transformer is usually specified as 1 ohm.
We have a site which where the ground conditions make it very difficult to get anywhere near that figure which has prompted a debate about where the requirement for...
Gentlemen,
How would you size this particular cable ?
Service - 400V AC 50HZ TPN
Load 1666A
Power factor .91
Cable:- Single core XLPE AWA armour to BS5467 laid up in trefoil.
Installation - Direct buried in soil at 500mm below surface groups spaced 600mm apart
I have referred this to Pirelli...
Could anyone advise why power cables are arranged in trefoil groups ?
I suspect it is to negate induced or circulating currents but are there any publications which deal with the subject ?
Gentlemen (and ladies),
Is there a rule of thumb for approximating the triplen harmonics which are produced by IT and other equipment which would assist in calculating transformer size during the design process ?
In the UK the normal power system within a commercial building will comprise a...
Gentlemen (and ladies),
I would be grateful if you could help me to ascertain the phase to phase voltages which will result within a three phase star connected network should the neutral conductor become disconnected from the star point of the transformer. This occurred in a hospital recently...
