Yes, SWR is a problem for long power distribution lines, but only the very long ones.
There was a case I think in Canada where they ran into this problem. The transmission lines from one side of the continent to the other was an odd multiple of a quarterwave (1,250 km). Since a quarterwave acts as an impedance transformer, when they put a low impedance load at the far end, the cable transformed this to a high impedance at the generator end and they couldn't get power into it. The solution? Either fit impedance correction devices along the cable, or transmit DC power and convert it back to AC at the load end (they do that with a power cable running between the mainland of Australia and the island of Tasmania). Cheers, Mark VK3BYY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of kb9bpf Sent: Wednesday, 17 September 2008 4:26 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Does anyone else think of Power Factor like SWR? .... The main difference is that at 60 Hz, the wavelengths are EXTREMELY long. I'm wondering if engineers and technicians who deal with cross- country power distribution must have to consider SWR effects on the power transmission line. In practice in homes and small factories, I would think, the SWR on the line caused by a mismatch between the characteristic impedance of the transmission line and the load is an insignificant factor, like worrying about the SWR measurement shift caused by a two-foot RG-213 jumper on 160M. At least as far as the transmission line is concerned - no significant voltage and current nodes and loops developed along the line like on an RF transmission line. A simplistic or impractical way of looking at things? I don't know. Maybe. Works for me. ... Ramble off. 73, Brad KB9BPF ---
