- one from the north which fed half the main street
- one from the south which fed the other half
- one from the east which fed a side road. This was derived from what was known as a “farmer’s line”, being a single phase transformer connected to 2 phases of the local three phase higher voltage system, with a 480 V centre tapped secondary
In the middle of the village was a distribution pole with a prominent notice “Warning! These LV systems will NOT parallel”. I asked one of my colleagues what this meant and was told that the phasing of the farmer’s line was such that it was not possible to get a 0° phase difference between it and the other supplies.
Before the higher voltage line plant was upgraded, it was common in the middle of a cold winter night for one third of the village to be off supply (but not predictably which third).
I notice DK7FC says that domestic three-phase supplies are common in Germany. In both England and France the authorities do not like such arrangements and do their best to phase them out. The supply to our property was probably three-phase at some stage because the official fuse unit has had a notice stuck on it emphasising that this installation is now single phase.
John F5VLF
On 29 Nov 2015, at 10:42, Andy Talbot <[email protected]> wrote:
If you use two transformers on a 3-phase supply, with the primary windings in a SQRT(3) ratio, one connected in delta, and one in star across the supply; equal value secondaries when rectified will give you 12X ripple instead of the 6X normal achieved though full wave 3-Ph rectification.
Unfortunately SQRT(3) is not rational (becuz Euclid sez so!) so any turns ratios will be approximate, hence ripple will be degraded marginally
'jnt
[email protected]Researching history of RABSON, BLACKSHAW, GAUNTLETT, VERLANDER and ROBSONNE
