DCP 161 implementation April 1st and calculating KVA, maximum demand

The Ghost · Mar 20, 2018

I have alluded to this in previous threads. The commercial site I work on has asked me what I think the total KVA for the site is. Having looked at various ways of viewing this I am getting lost with it. So if I just say
kVA = ( V*A*1.73)/1000 and assume supply is 400V and take the main incomer fuse at 200a I come up with 138 kVA. Now I know for a fact that figure will never be drawn at the site.
However the energy provider suggests 80 kVA. The DNO has suggested an average of 60 kVA per month. So I am stuck between these figures, looking for a sensible way forward. It is important to get this right as if you order in excess of what you use you pay a significantly higher tariff whereas you pay a significantly higher tariff if you underestimate kVA and exceed the deman required. I have read more than enough around this but there is no simple answer it appears. I do think the DNO/energy supplier is expecting a lot from the end user in having to deal with this. Anybody have any constructive ideas?

Richard Burns · Mar 20, 2018

No particularly constructive advice I am afraid, but I would agree that to provide an accurate figure is complex and probably unreasonable. However the energy user is in the best position (still not a good position) to be able to determine this figure.
A practical approach would be to monitor usage over time assess if this is normal usage and apply for the maximum measured value and make later adjustments should the use of the installation change in the future.
Complex compounding of load profiles from individual circuits/equipment would seem to be the only other way to get a vaguely accurate figure but would take a lot more time and probably be no more accurate than measurement.
Presumably the DNO want you to state 100kVA and pay for that so they get the money even if you only use 40kVA.
You would have to compare the tariff costs and over usage charges and see where it is most cost effective to pitch the declared figure.

The Ghost · Mar 20, 2018

I had (for a nanosecond) considered looking at a site wide calculation however there are 67 units various sizes and loading of different types and unknowable (without PQA) Pf and thought well that is not going to work practically speaking. What bugs me is 1. The DNO/energy supplier know full well the historic kVA. 2. They seriously expect the end user to be able to answer this question that I am stumped with even considering I may have a rudimentary enough knowledge to work it out! It is a bit of a lottery, and searching the web there is a plethora of sudden "energy experts" that can deal with all of this with the caveat they may be brokering energy and cut you into a very expensive contract that if you understood you would in no way sign. Oh dear. Is no one else being asked this? As the DNO/supplier are blithely stating to the customer "Just ask your electrician" Magic!

PEG · Mar 20, 2018

Hi,have you got access to their historic billing/usage?

This,coupled with some data logging,during the heavier use periods,assessed from the above,would yield a clue.

In these situations,it may be prudent to supply only,the use information,and not any opinion on the customers spending decisions. Let them be the judge of any bet hedging,or you may give them a convenient,non-board target,for finger pointing

The Ghost · Mar 21, 2018

Thanks for the input @PEG and @Richard Burns I take it the silence from other members means this is an issue that is not really easy to answer and I should not beat myself up too much in not being able to answer the question. Yes I can get historic kWH usage that is not a problem. The thing is it is the peak kVA minute to minute. Without an expensive data logger hire I cannot see how to get such info. However there is one small possibility for the client. I have told them to get a Stark account. Apparently if you are on a smart meter, by law, you must have a means of interrogating the meter. You can do this online and record all sorts of information. I don't know all that much about it but it seems the HH smart meters are the equivalent of a PQA and have algorithms built in to calculate the Line Loss, kVAr, kVA, kWH as well as peak values. Anyway the long and the short of it is that if I tell them the wrong figure they will be pointing the finger at me for the financial penalties. This is crazy that this is now the way you have to strategise using energy.

PEG · Mar 21, 2018

Hi,i cannot think that the hire of a data logger,equates in any shape,to the costs involved regarding a wrong and binding contract agreement.

The bigger these companies are,the happier they are to obviate responsibility,and attribute blame....unless it is a financially astute decision...in which case,there is usually a pecking order of company glory baskers

Even Putin is havin'a go...Salisbury was a targeted hit,by our own government,apparently...