max demand at petrol pump

[Engineer54]

Mad Spark, that's why they cost so much to hire, they DON'T guess, they calculate!! The same way your MFT test kit calculates various readings... These units are very sophisticated bits of kit. If your that worried, then hire a unit that has 3 voltage inputs one for each phase, believe me you don't need too, for the information your requiring!!

 

[Mad Spark]

I really admire your knowledge engineer54 and your determination in letting us have a little portion of it too, however on this occasion I just cant see how its possible to calculate something that its not being fed. But as I said earlier you are the man with the know how and experience and I totally respect ya. Thanks for all your input on this matter

 

[Engineer54]

Mad Spark, ....I use these units on a fairly regular basis, they do exactly what it says on the box!! I've never had any reason to doubt the information/values i've been given by any of them...


Just think about this for a second or two, just how much do you think the supply voltage is going to differ between each of the phases?? Go look at the specifications of one of these units, you will probably find accuracy % figures for each parameter the unit records. Your worrying about nothing!! lol!!

 

[MarkieSparkie]

Mad Spark, ....I use these units on a fairly regular basis, they do exactly what it says on the box!! I've never had any reason to doubt the information/values i've been given by any of them...


Just think about this for a second or two, just how much do you think the supply voltage is going to differ between each of the phases?? Go look at the specifications of one of these units, you will probably find accuracy % figures for each parameter the unit records. Your worrying about nothing!! lol!!

Hi madspark, I can echo E54 excellent advice. Your client is a commercial business, his/her largest fixed overheads are staff wages and energy cost. If you put a sound case of accurately assessing their typical energy usage and the possibility resulting from it of trimming their energy budget they are likely to grab the opportunity because of the economic climate and the spiralling cost of energy.

 

[Knobhead]

The last time I used one of these units I was working on a 3.3KV supply. The unit was quite happily doing it’s job using 230V as it’s reference.
It highlighted we were wasting a lot of power, that caused me headaches later but that’s another story.

at £80+ VAT to hire for a week it seems good deal to me considering what could be saved.

 

[UKMeterman]

Hi,
There are a number of further questions;
1. Are there any TRUE three phase loads on site, loads that do need 400V? If so could you even get a smaller 3 phase supply?
2. Are there any particular safety requirments regarding petrol stations if the mains intake is altered.
3. Have you considered fitting a sub meter with GSM loging facilites ?

 

[Mad Spark]

Hi lads,
I took your advice on board and have aquired the energy analyser, I have had it running at site for three days before i went to fetch the results. its seems great really easy to set up and to remove, as described earlier its fool proof, ahh....
Now ive downloaded all data on to my laptopo and looking at the graphs I'm getting confused can you guys help please.
The problem I'm having is I'm not sure weather to calculate KVA for each phase seperatly and then add together, or just for the one phase which has the highest reading. I am assuming that I should calculate for each one. But do I simply add them all together for a final figure or is there another way.

 

[Mad Spark]

i have to say engineer54 i now understand 'how it can get the value for the 3 phases now being only plugged into one', me eating my words here.

 

[Engineer54]

Why are you needing to calculate KVA, ...the energy analyser should be giving you actual measured KVA results. In fact you should have results for, ....A, KW, KVA, KVAr, THD, V, etc.

Not much of an analyser if it doesn't give you all of those and a few more parameters too.

What make and model of analyser did you hire eventually then???

 

[Mad Spark]

just to clarify ukmeterman, the incoming are not going to be alterd at all he is on a 06 meter which is used for heavy industries, whereas for petrol stations normally 03/04 are suffice, so he was asked from his supplieer to find out kva at site for them to asertain if he is on the right tarrif or not, and sorry for not answering your questions sooner just been runing around and havent had the chance. you know how it is trying to earn an honest buck.

 

[Mad Spark]

e54 it was the one that i was recomended, ive still got it, its the spcpro if that makes sence
so ive got current1, current2, current3, power factor, voltage, energy (kwh), power (kw), cost, CO2
its printed out various graphs for each of these paameters too but no kva
can you remind me what kvarh is again please?

 

[Engineer54]

Spent a bit of time looking for that Logger you have been using, i think it's the SPC pro by Elcomponent, is that right?? They actually have a fair range of logging analysers.

Never used the SPC pro, but your right, it doesn't do VA/KVA, the only unit in there range that doesn't lol!!. Probably why i've never used one!! To be honest i've mainly been using fluke, Chauvin Arnoux, and a couple of others makes when it comes to Analyser logging units. You would have thought that all these loggers would have an apparent power KVA parameter for each phase and combined. More use than a dammed CO2 parameter!! lol!!

Oh, KVArh Is reactive power...

 

[Mad Spark]

thats just what i was thinking, who and why whould any one need co2, i dont get it, any way, wat i think i'm gonna do is multiply highest current by 400 on each phase and multiply by 80% for the power factor,( phase 1 maximum current usage at any one point was 27A, 55A for phase 2, and 8A for phase 3) and then add each phase to get total kva.
do you think thats the right way.
the only thing i'm wondering is weather its like a resistor, ie 1/r1+1/r2 ....=1/rt, or is it just a normal addition.