| Forum Home | ||||
| PC World Chat | ||||
| Thread ID: 56151 | 2005-03-28 11:59:00 | Crazy power hungry Aucklanders | Strommer (42) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 339117 | 2005-03-30 07:41:00 | oh boy~ oh boy~ You kiwi's need to realise that the world does not revolve around rugby, cricket and agriculture.... |
techie (7177) | ||
| 339118 | 2005-03-30 07:56:00 | oh boy~ oh boy~ You kiwi's need to realise that the world does not revolve around rugby, cricket and agriculture.... You un kiwis should realise that it does. |
Cicero (40) | ||
| 339119 | 2005-03-31 02:40:00 | ...damn timeouts ... | Graham L (2) | ||
| 339120 | 2005-03-31 02:41:00 | A few farmers used to light their cowsheds with electricity acquired by running a fence line underneath the overhead AC lines. Earthing the far end of the fence let them use earth return. DC lines don't work like that; perhaps that's the reason for the objection. ;) I suppose a generator coupled to an electrostatic motor with a corona collector might extract some energy from a high voltage DC line ... :cool: |
Graham L (2) | ||
| 339121 | 2005-03-31 02:50:00 | Actually Graham, you would be surprised how much induction you can collect from under a DC line. I know, I have measured and analysed it many years ago. The Benmore - Haywards DC link is apparently "12 phase" rectified, with a high ripple content, at reasonably high frequency from the 12 phase input to the rectifiers. The frequency spectrum was horrible. But you cannot collect the power that you can from AC, afterall that is why DC is used as induction losses are lower. |
godfather (25) | ||
| 339122 | 2005-03-31 03:01:00 | I suspect the main reason is "1.414". It's certainly the main reason for DC in cables ... you get that much more capacity for the same insulation. When you get to hundreds of KV it makes a difference to the insulator size for overhead lines too. | Graham L (2) | ||
| 339123 | 2005-03-31 03:20:00 | It is better explained here: www.transpower.co.nz Its more the loses from capacitance with AC |
godfather (25) | ||
| 339124 | 2005-03-31 06:31:00 | Sorry George but it costs many $million for each offtake on a 400 kV DC line. While I agree with Graham entirely on costs, it would be good to see a rational public debate with the cost of underground declared. While I am sure that we simply could not afford it, it would be useful to actually see the $ involved. Underground cable costs for 400 kV would be horrendous, compared to overhead but by how much? I was more referring to an approach involving a digger and some spikes and wires. Stab the spike into the right part of the wire and hey presto 400kV DC. And I meant MW, stupid me! But I wonder, how on earth do they convert it to sine-wave AC at such high powers? Several MW inverters aren't the kind of thing you see on DSE shelves! |
george12 (7) | ||
| 339125 | 2005-03-31 07:08:00 | But I wonder, how on earth do they convert it to sine-wave AC at such high powers? Several MW inverters aren't the kind of thing you see on DSE shelves! Try to imagine HUGE mercury arc rectifiers, and HUGE thyristors inverters together with HUGE rotary synchronous capacitors weighing a few tons . I had the job of checking bearing alignment of the rotary capacitors back in NZED days during regular maintenance . |
Terry Porritt (14) | ||
| 339126 | 2005-03-31 08:43:00 | Would a DC transmition line radiate the more or less than AC. I am thinking of the effect on the human body of living in proximity to high voltage line which may or may not (depending on which side of the argument you take) cause various illnesses that have been reported elsewhere. | craigb (4884) | ||
| 1 2 3 4 5 6 7 8 9 10 | |||||