800M 32mm SWA - could this cause increased electricity bills due to voltage loss

What am I looking for for a monitor and by clip on do you mean I can just stick it on the cable? (its swa so will it work). Thanks

That transformer is a 20KVA ( ~ 90 amp ) unit, and the data sheet quotes 98% efficiency, but it is not clear how the loses vary with loading.

If the loss is constant then 2% of 20kw would be 400W. Not all of your static load, but certainly a chunk of it.

more realistically I imagine that 2% loss is at fulll load however, and  the losses are reduced to perhaps half that at low load, but could still be a few hundred watts running all the time.


Now if you ever did want the full 90A then that 35mm cable would drop nearly 90V (being about 1 ohm round trip, half an ohm there and half an ohm back  ) so you can see why the self adjusting transformer is attractive.


However a circuit that kicked the transformer off and connected directly when the house load fell below perhaps a kW or so would be worth having.


It does leave one to wonder if having the HV mains and a pole-pig transformer brought nearer would have been a better option when the place was built . Probably too expensive now.

There is a good reason that the LV network does not have very long runs in if it can be avoided. (a long run as a quick rule of thumb is scales with the voltage, 12m is a long way for a power circuit at 12V,  400m is a long way at 400V, 11km is a long way for an 11kV line etc.  Does not mean impossible, but may mean oversized cables or special tricks or needed - rather like this.)

Mike

Simple things first: Arrange your living to manage with your consumer unit turned off for say 4 hours and take a meter reading at the source and again at the end of the time period. There you'll have the parasitic load and can work out by multiplying this by 6 and then by 365 to get your annual "no appliance etc" load. Obviously better if the 4 hours is extended to 6 or 8 to get better accuracy.


Regards


BOD

Eliminate Voltage Drop in Long Cable Runs and SAVE on Cable Costs


Quick. patent that cable! A way round absolute zero!


Regards


BOD

The transformer seems to be rated at 91 amps, so is possibly two or three times bigger than it needs to be, would having a smaller transformer reduce the losses?

Thanks for all the replies. General consensus is that it shouldn't be making a significant difference.


Average uk consumption is 3600kwh, and that will include all the really heavy users as well, so 6000 plus a year is really very high.


I'll flick off the consumer unit, one afternoon whilst I am out and see what the zero load consumption is first then move in to some of the other suggestions.


I've also started an application for a new meter and supply for the house, the situation might have changed over the 30 years or so since the decision was taken to site the supply all that distance away.


Thanks

Perhaps I'm being rather slow here, but  assuming a constant 230 V at the origin of 800 m of 35 mm2 with a 30 A load at the end you'd end up with about 203 V at the end. Power in = 6900 W, power at end = 6090 W so there is 810 W loss in the cable.

If the magic box receives 203 V and ups it to the desired 230 V from the delivered 6090 W, we get 26.5 A at 100% efficiency. At 98% declared we get 26 A 

But we want 30 A at 230 V so to get this 6900 W we have to supply more than 30 A at the origin.

Let's try 34 A at the origin.

Voltage at end 200 V. Power in = 7820 W. power at end = 6800 W so there is a 1020 W loss in the cable.

Again with receiving 200 V and ups it to the desired 230 V from the delivered 6800 W, we get 29.6 A at 100% efficiency. At 98% declared we get 29 A. Getting closer.

Try 35 A at origin. Voltage at end 199 V. Power in = 8050 W. power at end = 6965 W so there is a 1085 W loss in the cable.

Again with receiving 199 V and ups it to the desired 230 V from the delivered 6965 W, we get 30.3 A at 100% efficiency. At 98% declared we get 29.7 A.

There must be an easier iterative way but to get our 30 A supply at 230 V, we must supply 35 A at the origin. A true efficiency of around 86%. 17 p/kWh at origin becomes 20p/kWh..............


Anyone care to do the calcs for the installed 20 kVA?


It is past my bedtime so EOE and I welcome your replies and corrections!


Regards


BED

I've also started an application for a new meter and supply for the house, the situation might have changed over the 30 years or so since the decision was taken to site the supply all that distance away.


Guesstimates from members?


I'll start at £44k


Regards


BED (I mean it this time!)