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

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

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