Harold — You bring up an interesting comparison. Off-topic war story — I used to work for a small utility-type operation that, partway during my stay, cut over from an older distribution-station of two semi-parallel feeders with crossarm-mounted air switches that allowed for limited sectionalizing for restoration and maintenance. To increase reliability and confidence in service continuity for some “picky” customers, a new station more centered in the area, the feeder count went from two to four, with some air switches left open and some ran normally closed. The pole-line feeders were laid out in roughly a figure-8 pattern.
The day after cutover me and an oldtimer lineman went around in a bucket truck to all the normally-open switches, and after proving that each side of the switch had the normally expected three ø-ø voltages we would test across each open switch pole to be sure we had zero volts, to minimize the chance of later fireworks and outages. It was a day of some nice, low-pressure overtime. One term for step-by-step planned switch operation is “sectionalizing.”
Switching aside, it’s the effectively same idea as 230V 2-wire ring circuits, except in the 3ø 5-35kV range.
[This message has been edited by Bjarney (edited 08-21-2002).]
