Basler Electric BE1-BPR - Manual (Page 14)

1-2 BE1-BPR General Information 9272000990 Rev J
Three major factors should be considered when establishing a reclosing philosophy.
• Desired number or reclosure attempts.
• Time delay between breaker opening and reclosure.
• Supervisory control.
The first major factor is the desired number of reclosure attempts. Where most faults are attributable to
heavy tree exposure, as in distribution networks, multiple reclosure attempts are common. This is
possible because of low voltage levels and is desirable considering customer inconvenience during
outages. BE1-BPR relays are programmable for up to three reclosure attempts per sequence. This allows
tailoring of the reclosing sequence to the specific needs of the circuit.
The second major factor is the time delay between breaker opening and reclosure. On sub-transmission
and distribution networks, it is necessary to ensure that motors are no longer running and that local
generation is off-line prior to attempting reclosure. At the same time, a rapid reclosure minimizes damage,
ionization, and system shock in transmission networks. After the first reclosure attempt, additional
attempts are generally delayed to allow for de-ionization of the interrupter. BE1-BPR relays have three
reclosing shots and each shot has a programmable time delay. Three outputs are available. They are
CLOSE, RECLOSE FAIL, and LOCKOUT.
A third major factor to be considered in reclosing is supervisory control. Supervisory control allows the
operator to maintain control of the system at all times. BE1-BPR relays have two supervisory inputs
(WAIT and LOCKOUT). WAIT stops the reclose sequence at any point and allows the sequence to
continue when the WAIT input is removed. LOCKOUT drives the reclose function immediately to lockout
status and takes precedence over all other inputs.
Timing Diagnostics
To perform the typical breaker failure operation previously described, the breaker failure relay must be
informed by a breaker failure initiate (BFI) contact that the breaker is being opened. One or more timers,
in conjunction with the overcurrent element, determine if the breaker failure output (BFO) picks up.
Typically one or more delay timers are used to delay the BFO until the primary protection scheme has
had enough time to operate. A control timer may be also be used to turn off the BFO after the backup
protection has had enough time to operate.
Calculation of the correct timer values is an important part of setting up the relay. You must know how
long it takes for the internal and external devices to operate. Typical timing sequences are listed in the
following paragraphs and shown in Figure 1-1. Parentheses in the listed timing information indicate
related times in Figure 1-1. Specific timing data for BE1-BPR relays is provided in the latter part of this
section.
(1) Time for protective relays to operate — (this includes sending a trip signal to the breaker and
sending a BFI signal to the BE1-BPR).
Normal Breaker Operation Required Timing Information
(2) Time required for the breaker to open.
(3) Time required for the BE1-BPR overcurrent detector to drop out.
(4) Margin to allow for variations in normal sequence timing plus a safety factor.
(12) Control timer setting = the length of time to maintain the breaker failure operating window. Control
timer setting must coordinate with the high speed reclose delay (13).
(13) Time to allow for arc de-ionization.
(5) Time for the BFI overcurrent detector to pickup.
Failed Breaker Operation Required Timing Information
(6) Time required for the BFI contact to be recognized by the BE1-BPR.
(7) Time for the BF logic to operate.
(8) Time for the BFO relay to operate.
(9) Time for the external lockout relay to pickup.
(10) Time for the backup breakers to operate.
(11) Delay timer setting = the sum of (breaker operate time (2) + BF current detector dropout time (3) +
margin (4)) minus BFI contact pickup time (6).