8-56 BE1-951 Application 9328900990 Rev L
High-Speed Reclose
Each reclose time delay can be set as low as 100 milliseconds. If the application requires a reclose time
delay of less than 250 milliseconds, it is recommended that the close logic expression be modified to
prevent mis-coordination between the TRIP and CLOSE outputs.
A hold timer for each output relay is provided to hold the output closed for approximately 200
milliseconds. This prevents the relay contacts from opening before the breaker auxiliary contact interrupts
the trip coil current. For high-speed reclosing, the hold timer must be disabled so that the output contact
follows the VO1 output expression. To modify the logic, add the expression "reclose 79C AND NOT trip
VO1 to the close logic. Examples 1 and 2 show a close expression and hold disable setting for high-
speed reclosing.
Figure 8-20 illustrates this high-speed reclose interlock logic scheme.
Figure 8-20. High-Speed Reclose Interlock Logic
Example 1. Close Expression: SL-VO2=79C*/VO1+101C
Example 2. Hold Disable Setting: SG-HOLD1=0
Block Load Tap Changer
A block load tap changer output is not provided in any of the preprogrammed logic schemes. However,
one of the output relays can be programmed to operate when the recloser is running (79RNG) and wired
to energize a normally closed auxiliary relay. The 79RNG logic variable is high when any of the timers are
timing and low when the reclosing function is in a lockout or reset state.
Block Neutral and Negative-Sequence Protection
The neutral and negative-sequence overcurrent elements provide greater sensitivity to unbalanced faults
than the phase overcurrent elements because they can be set to pickup below balanced three-phase
load. This can lead to a mis-operation during periods of load imbalance. The BE1-951 provides a neutral
and negative-sequence demand function that allows monitoring and alarming to prevent load imbalances.
However, distribution systems with single-pole fault clearing and switching devices or long single-phase
laterals may have mis-operations during switching activities.
Preprogrammed logic scheme OC-W-79, OC-W-CTL and FDR-W-IL accommodate the use of a cutoff
switch to block the ground and negative-sequence 50T (used for low-set instantaneous) and the 51
(inverse time) function blocks during switching activities. This is the most conservative approach. You
may wish to evaluate this strategy based on your system, operating practices and setting practices. For
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