Information on time settings for Reclosers

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Sandlapper

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Wanted to ask the Utility folks if anyone is aware of technical papers available for setting up reclosers for protection of overhead distribution lines. Particularly interested in how the time intervals between initial open on a fault, the reclose, and eventual lockout are selected. Thanks in advance.
 
This is done by relay oprating on fault on line o-0.3sec is reclosing operstion by autorecloser , since cb is already charged it will take 0.3 s to close but next reclose order cb has to recharge it operating mechanism and it will take 3 min to recharge its spring or hydraulic system and then able to reclose. again closing is done immediately in 30 millisecond time actuall it should be like this

O-0.3S-C-0.03S-O-3MIN-C-0.03S-O

ONECE THE CB OPENED BY RELAY ON FAULT, IT WILLTAKE 0.3S TO CLOSE AGAIN AND RECLOSING ORDER WILL BE GIVEN BY AUTO RECLOSER. WHEN CLOSED RELAY WILL OPEN AGAIN IN 30 MILLISECOND (30 MILLISECOND IS CB OPENING TIME.




The (3 min) is the time interval between two operations which is necessary to restore the initial conditions and/or prevent undue heating of parts of the CB.


Yes there is differences on the thermal properties.3 min will allow the breakes to cool down and stable restart.
 
Per "Power System Analysis", Charles A. Gross

Per "Power System Analysis", Charles A. Gross

"The recloser senses overcurrent and breaks the circuit, instantaneously or after an intentional time delay. After a short preset interval [usually 1/3 second (20 cycles)] the recloser "recloses." If the fault persists, the recloser again trips, and waits a second preset interval (usually 15 seconds). The recloser, being a persistent little devil, closes again, only to trip if the fault is still there. After a third open interval (usually 45 seconds), the recloser closes one last time. If the fault persists, the recloser opens and "locks out," . . ." I have set intervals along these lines. Consideration for first reclose is time for ionized air from a lightning stroke to dissipate. The 20 cycles seems to work. Squirrels or birds might still cause a fault after 20 cycles, so the 15 seconds seems to work for them. I always thought the 45 seconds involved more risk of a downed line being approached by the curious or rescuers. I did a study of our Florida system and found the third reclose to be rarely successful. We considered eliminating it because of the risk and its low success rate and the added stress to components. If you have solid state relays and good records, you can look at your system's performance and adjust your intervals to suit. Solid state relays can also be set to lockout immediately if the fault exceeds a set level. You preserve your system by not reclosing on high amp faults.
 
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