Utility distribution feeder reclosing timing
Utility distribution feeder reclosing timing
(OP)
Questions were started in previous threads. Can anyone discuss their reclosing scheme for a utility distribution feeder including target reset (manual or automatic upon successful reclose), reclosing open interval timing (how long do you leave the feeder off before attempting reclosing?), how many reclose attempts do you take before lockout and how long to you let the reclose relay (79 device) be shot advanced before you reset it to it's first shot? I'd also ask you to denote if you're using reclosers or breakers w/relays. If breakers, what about the breaker duty cycle as it relates to the reclose interval and number of attempts.
Thanks!
Thanks!






RE: Utility distribution feeder reclosing timing
RE: Utility distribution feeder reclosing timing
RE: Utility distribution feeder reclosing timing
1. Arc deionizing time.
2. Possibility of multiple lightning strokes.
3. Effect on customer equipment.
4. Breaker duty cycle.
5. Reset time of upstream overcurrent relays.
I like to make the first interval 2 seconds for the second factor. This conflicts with the third factor, however. An immediate reclose may keep customers' computers from tripping off. Breakers usually require at least a 0.3 second interval which will make most computers trip off anyway.
RE: Utility distribution feeder reclosing timing
Long rural overhead feeders are going to experience more 'transient' faults from branches/squirrels/lightning/etc, and we therefore may use 3 shots to lockout (i.e. 2 recloses) to maximize the chances of an automatic restoration.
Dense urban underground feeders tend to have only 'sustained' faults, and we use only 2 shots to lockout ( 1 reclose), since faults tend not to go away, and you don't want to beat up your system any more than you have to.
RE: Utility distribution feeder reclosing timing
RE: Utility distribution feeder reclosing timing
RE: Utility distribution feeder reclosing timing
For overhead feeders we generally go with one fast trip with high-speed reclose (2 or 3 cycle delay) and then two slow curves with 5 to 10 sec delay. I've never seen much point in delaying beyond 10 sec, but a lot of people use greater delay times.
RE: Utility distribution feeder reclosing timing
What I want to know is; what "reset" time do you use after a successful reclose for the 79 circuits to go back to a "normal" mode?
RE: Utility distribution feeder reclosing timing
Two feeders exited a station on double circuit structures. A tree through both lines caused a circuit to circuit fault. Recloser A would operate a few times, then recloser B would operate while A reset, and so on. High side fuses eventually cleared the fault after way too many recloser operations. Incident 2: On a cold winter morning, a coworker complained of all the blinks he saw at home prior to coming to work. I went to the station in question, and watched the recloser bang away. It would stop just long enough so it could reset, then it would start banging away again on the overload.
RE: Utility distribution feeder reclosing timing
http://www.pes-psrc.org/i/
Click on the "Published Reports" link then scroll down to the Working Group Report "Results of the 2002 Distribution Protection Survey".