Reclose Attempts; Conductor Damage Curve
Reclose Attempts; Conductor Damage Curve
(OP)
Are there any distribution protection engineers who consider the conductor damage curve when deciding on the number of reclose attempts?
It seems fairly common to compare the timed-overcurrent curves with the conductor damage curve.
However, if there are reclosing attempts, the conductor will heat up during the first operation, trip and cool down during the open interval, then heat up again on the reclose onto a fault.
The timed overcurrent curve may be below the conductor damage curve for 1 individual operation, but with successive operations, the *combined* exposure to fault current and duration could be above the conductor damage curve.
(In other words, multiply the timed overcurrent curve with the # of operations to lockout and compare this curve against the conductor damage curve)
Does anyone consider this?
It seems fairly common to compare the timed-overcurrent curves with the conductor damage curve.
However, if there are reclosing attempts, the conductor will heat up during the first operation, trip and cool down during the open interval, then heat up again on the reclose onto a fault.
The timed overcurrent curve may be below the conductor damage curve for 1 individual operation, but with successive operations, the *combined* exposure to fault current and duration could be above the conductor damage curve.
(In other words, multiply the timed overcurrent curve with the # of operations to lockout and compare this curve against the conductor damage curve)
Does anyone consider this?






RE: Reclose Attempts; Conductor Damage Curve
RE: Reclose Attempts; Conductor Damage Curve
Regards
Marmite
RE: Reclose Attempts; Conductor Damage Curve
RE: Reclose Attempts; Conductor Damage Curve
However, our typical open intervals are on the order of seconds, and I doubt that the conductor would be able to cool to pre-fault temperature during the open interval.
It seems to me that there must be some kind of reasonable approximation between: assume no cooling during open interval, and assume conductor cools back to pre-fault temperature.
stevenal, do you consider the conductor damage curve when setting open intervals? Or, are you increasing the open interval time on subsequent operations to allow the fault to clear itself (bird to fall off, tree to swing away).
RE: Reclose Attempts; Conductor Damage Curve