If the starting voltage is 240V, and the impedence is 0.2 ohms, then you could generate 16.5 kW before hitting 253V. Trouble is, 240V is quite low for even a nominal 230V supply. Its not uncommon to find some that are already at 250V! A throwback from the days when the UK supply was 240V, but without any action from the DNO's to do anything significant about it when the voltage dropped to 230V nominal! 0.2 ohms is also a very optimistic impedence, typical of what you might find with a 16 or a 25 kVA transformer on a pole near the end of the house (rural setting assumed!) with a bit of good cable between that and the consumer unit.
If your "no turbine voltage" is 245V (very typical) and the impedence 0.28 ohms (also very typical), then 253 volts is reached with a mere 7.2 kW of generation.
If there is a long cable (or even any cable!) between the main consumer unit and the inverters, then the problem is worse. The above typical impedances are based on measurements at the meter / consumer unit. If there is a long cable to where the inverters are going, such as between a house and an outbuilding, then the impedence can easily double.
All this is aside from gaining the permission of the DNO, who have to give approval for such a sized connection to single phase. If their calculations show that 253V will be exceeded, then the connection will be unlikely to be permitted unless the network is re-inforced.
Oh, and be aware of installers who simply tweak the inverter settings until it stops tripping! 253V is the maximum permitted under the ESQCR regulations. Any installer who tells you they can set this up to only trip at 264V or even higher, need to know a little bit more about the regulations in this country! And to have ready a good excuse as to why the electrical appliances in your house have such a short life!
|Proven 15KW into Single Phase ...||Tony Smith - 1/09|
|Re: Proven 15KW into Single Ph...||Bryan Rendall - 3/09|