Still dont know where my power is going - can someone help?

[splyn]

I recall reading of a family who turned their power off when going on holiday. On return they were confronted by an incandescent neighbour, a fish and chip shop owner who'd lost the entire contents of his freezer in his outhouse ... the supply for which he'd tapped into the cable running to his neighbour's shed. And from his rantings and ravings it seems he was the aggrieved party! 

Got any close neighbours? 

[rogeriko]

What happened? inquiring minds want to know, Was exmoor plunged into darkness or is the meter still whizzing around?

[guydewdney]

the guy at goodenergy has been on holiday - but a new meter has been actioned... and A1100 doesnt work, a A1140 or A1700 is required.

Guy

[Philip R]

Decided to pitch in an say my two penny worth.
Harmonics,Harmonics, have you looked at the harmonic output of all those invertors you have. I asked because you may have failed harmonic filters in your system invertor(s) feeding a noisy non sinusoidal waveform into your metering.

A while back St B made some observations about the sampling rate of some metering devices. Both Voltage and current have to be sampled to integrate the product with respect to time. I do not believe that that these meters like harmonics that much. Any opinions?? You have invertor sources all over the shop.

Try and get hold of a good old fashinoned Ferraris wheel meter, the sort with a disc in it that spins round. These devices are fairly tolerant of phase imbalance and some harmonics. You could set up some single phase ferraris meters on each phase or in the "two wattmeter" configuration.

Do youk now anyone at your local utility company or at the local depot of SWEB ( Whatever they are called now, with a check meter (sub standard) no not substandard but calibrated from the standard.) If you ask them nicely, they might even give you one.

PhilipR

[book_woorm]

If you've still got a problem when the meters have been changed then I would check your nutral to earth voltage!!! Yes I know it should be zero but it often isnt!! Assuming that all your systems are star 3P and N and ther is no delta configuration once your phases are out of balance the nutral moves away from where it should be and you can get high out of tolerance voltages on the circuts on one of the phases. Your clip on ameter is not telling the whole story unless you are measuring the voltage at the same time. Remember power is the square of the voltage, so the voltage only has to go up 10% to consume 21% more power!

I have a slight but similar problem here with the PV, as the impedence of the nutral/earth back to the substation is greater than the line impedance when my PV is on full chat it pushes the nutral down rather than the line voltage up

[StBarnabas]

Sorry Guy
Day Job has been very hectic recently. I agree with BookWorm. Assuming you are Star rather than Delta connected I would check your Earth and Neutral. If your phases are well out of balance. Harmonics are also worth looking at as
Philip says

[guydewdney]

ok - will monitor N to Earth - but do you mean local earth (rod in the ground)?  The system I have the earth wires are all tied to the N at the service head (whatever thats called - TTNS and all that). Will measure to real earth I presume?

[book_woorm]

Yes I do mean local earth, its the impedances on all 5 wires back to the substation that matter.

I looked in one of my old texbooks lastnight and made some PDF's of the relivant pages. (As each one would blow the attachment limit, Let me know your real email address and I'll send them along). Quite a few 3ph systems only measure one phase and asume that all is in balance!! If you look at artical 13.10 and the vector diagram 13.31, if one of the loads is a generator then the vectors for that phase will be reversed by 180 deg and you get some very funny results.

Safest solution is three meters, individual phase to nutral for import, same again for generation and AGAIN for expot!!

[guydewdney]

well, I have a 3 phase gen meter on the solar - which is always generating on all three phases, just out of 'balance'. I have two separate meters on the hydro gen, again, out of balance. I have shortly to have a new spangly meter that will be ok for unbalanced three phase....

email sent with my email address on it.

[book_woorm]

Hope the textbook stuff helps,

I ment to ask, I assume you got your brearing problem sorted. If I had seen it earlier I would have sugested using either Marine Cutlass Bearings which are water lubricated or Orkot ones which are self lubricating.

[book_woorm]

did the new meters cure the problem?

[StBarnabas]

Guy
also interested to know what the issue was. Is it working now?
Sean

[guydewdney]

still waiting on the new meters