ABB REC650 Applications Manual page 216

Section 10
Control
210
Auto-reclosing open times, dead times
Three-phase shot 1 delay: For three-phase High-Speed Auto-Reclosing (HSAR) a typical
open time is 400ms. Different local phenomena, such as moisture, salt, pollution etc. can
influence the required dead time. Some users apply Delayed Auto-Reclosing (DAR) with
delays of 10s or more. The delay of reclosing shot 2 and possible later shots are usually set
at 30s or more. A check that the CB duty cycle can manage the selected setting must be
done. The setting can in some cases be restricted by national regulations. For multiple
shots the setting of shots 2-5 must be longer than the circuit breaker duty cycle time.
tSync , Maximum wait time for synchronismcheck
The time window should be coordinated with the operate time and other settings of the
synchronism check function. Attention should also be paid to the possibility of a power
swing when reclosing after a line fault. Too short a time may prevent a potentially
successful reclosing.
A typical setting may be 2.0 s. In cases where synchronization is used together with auto-
recloser the time must be set to 100-600s to allow operation at minimum frequency
difference.
tTrip , Long trip pulse
Usually the trip command and initiate auto-reclosing signal reset quickly as the fault is
cleared. A prolonged trip command may depend on a CB failing to clear the fault. A trip
signal present when the CB is reclosed will result in a new trip. At a setting somewhat
longer than the auto-reclosing open time, this facility will not influence the reclosing. A
typical setting of tTrip could be close to the auto-reclosing open time.
tInhibit , Inhibit resetting delay
A typical setting is tInhibit = 5.0 s to ensure reliable interruption and temporary blocking
of the function. Function will be blocked during this time after the tinhibit has been
activated.
tReset , Reset time
The Reset time sets the time for resetting the function to its original state, after which a line
fault and tripping will be treated as an independent new case with a new reclosing cycle.
One may consider a nominal CB duty cycle of for instance, O-0.3sec CO- 3 min. – CO.
However the 3 minute (180 s) recovery time is usually not critical as fault levels are mostly
lower than rated value and the risk of a new fault within a short time is negligible. A typical
time may be tReset = 60 or 180 s dependent of the fault level and breaker duty cycle.
StartByCBOpen
The normal setting is Disabled. It is used when the function is started by protection trip
signals.
1MRK 511 286-UUS A
Application manual