Balancing a 3 phase supply

[Wrighty321]

Hi All,

I'm new to this forum, so Greetings from Macclesfield in Cheshire

My first question for you to ponder, regards a client of mine who has aquired a commercial buiding with a 3 Phase supply and a meter.

Now - the building has obviously had several changes of use in its life time. There is no 3 phase equiptment in the building now and the 3 phase distribution board looks fairly unbalanced with its array of outgoing single phase circuits.

The building is essentially split into 3, 2 seperate showrooms and a flat above.

He has told me that his electricity bill is very high, and without actually seeing his bill and taking him at his word it does seem excessive when all he is running are suspended ceiling lights in the 2 showrooms

The flat above has a domestic consumer unit which takes its feed from one of the phases, and I am going to go back to monitor the load shared across all the phases, now i know its going to be difficult to balance, but with the above in mind, would it be better to advise him to get his supplier to convert him to single phase useage, or get the 3 phase meter removed and 3 single phase meters putting the flat and 2 showrooms on seperate phases.

Surely he will be paying more for the set up as it is?, and with the load being unbalanced am i right in thinking that he will be paying for the phase thats drawing the most current effectivley multiplied by 3 ?

look forward to your comments,

Regards

Wrighty

 

[Des 56]

An unbalanced 3 phase load can be an expensive un required expense
The 3 phase supply probably made practical or economic sense for the previous occupier

Your suggestion of one single phase supply seems the best solution if the existing load is within supply capability
It would need little in the way of alteraion/adaption or cost and would be my direction if no 3 phase equipment was being used
One standing charge would be a better cost effective than three seperate supplies which would also incur the expense of the alterations by the supplier

 

[Darkwood]

Find out what allowable kva the building is been billed for as if it was a heavy user in the past and no longer is then a higher standing tariff will be charged, also count the lighting up as showrooms tend to be heavy on lighting which will be expensive to run just because on light is cheap to run you will be supprised how much kwh is used lighting a large area.
The local DNO puts premises in to a higher tariff band about 110kva requested supply if memory serves me right.

 

[MikeCDF]

I did a job like this earlier in the year where a building was changed in use from an engineering workshop to a small warehouse.

The original 3-phase supply was for 3x 250A fuses and when I checked the loading on the installation then most of load was on Phase 1. It was a bit tedious but more or less balanced the load over upstairs office, downstairs office and warehouse (that was the work shop) removed old type fuses and replaced with shiny new ABB panel with MCB's and RCD's. Decided to advise keeping 3-phase supply as per kw cost lower and always useful in commercial buildings anyway.

Now customer has 63A main fuses and will save over £1,400 this year - he's already had £980 off his bill just for load balancing i.e. remove all the load from L1. The rest of the savings is because the building use has changed and the fuses are lower.

Definitely well worth doing. My bill for all this with materials around £3,800 but customer has already got some of this back and all of it within 2-years!

 

[piggyitm]

You could install a power factor correction unit but i cant say if it would be cheaper than a new single phase set up.