kilowatt hour meter

[izzy76]

hi
i got a 3ph 500amp distribution box with 8 63amp3ph isolators feeding other different sub distributions, i need to install a sub kilowatt hour meter on just 3 isolators feeders but dont wish to modify the main distribution .... can i clamp each phase with different current transformers and wire them so they feed a single 3ph 250amp kilowatt hour meter.... is it possible to wire the cts in a way so i can monitor the consumption (in parallel or in series) one ct for every phase respectively ...
i hope i was clear enough
thanks in advance

 

[piccollo]

izzy, Have you got a Main fused switch feeding a busbar chamber & then the 8 x3ph 63A switch fuses or a panel board with a main MCCB & 8x63A MCCB's. If the latter you may be able to install the CT's[ current transformers] within the common wireway [ ensuring the signal cable terminations are shrouded]. Then fit the meters on the top of the panel.[ all depends on access/ layout etc, this is one suggestion]
If you have a busbar chamber & seperate switch fuses, you may have to route the supplies to these [ or the 3 you wish to monitor] via an enclosure [ for the CT,s.] or in either case use direct reading check meters. I have presumed the3 phase isolators / switch fuses / MCCB's are feeding 3 phase boards & not 3 single phase boards [ which is bad practice for isolation]. Further info may give better idea of layout / distribution. piccollo

 

[izzy76]

hi piccollo ... yes i got a fused incomer feeding a busbar chamber , the 8 isolators are feeding 3phase dbs .... the 3 feeders i wish to monitor are feeding a part of the establishment, now the problem is that it is not possible to install a kilowatt meter for every feeder cause of space and budget, if each of the phases example the brown phase of each feeder is passed through the concerned ct will it read the total amount of current passing through the 3 different feeds? one ct with 3 brown cables passing through it , same is done on the black and on the gray... will the cts sum up the current flowing?
thanks for ur interest and help

 

[piccollo]

izzy, yes you can use one meter. Suggest insulated enclosure [ mounted on or near bus bar chamber with insulated studs/ short bars to house CT's & local 6amp fuses / 3 phase 6 amp mcb] renew tails [ unless you can easily get them through CT aperture], you will know what space you have, then local fuses can be fed off of the stud [ min 6mm2] or one of the isolators. I don't like putting CT's in a busbar chamber as generally not a lot of spare room. piccollo