Basler Electric BE1-79M - Manual (Page 11)

9170100990 Rev N BE1-79M General Information 1-1
SECTION 1 • GENERAL INFORMATION
Purpose
The BE1-79M Multiple Shot Reclosing Relay automatically recloses circuit breakers, which have been
tripped by protective relays or other devices in power transmission and distribution systems.
• Over 90% of faults occurring on overhead lines may be cleared by momentarily de-energizing the
line. Once the circuit breaker has been opened to de-energize the line, the BE1-79M provides a
reliable automatic reclosure. The advantages are:
• Improved Service Continuity - returns the line to service quickly, preserving line integrity and
minimizing outage effects on critical loads.
• System Stability - prevents disjointing of the system grid.
• Higher Line Loading - decreases likelihood of loss of line.
Application
Four major factors should be considered when establishing a reclosing philosophy.
• Desired number of reclosure attempts.
• Time delay between breaker opening and reclosure.
• Supervisory control.
• System coordination.
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. The BE1-79M is programmable for up to four 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 subtransmission
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. The BE1-79M incorporates one
instantaneous reclosing attempt with bypass capability, and up to three individually adjustable, time-
delayed, reclosing attempts.
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. The BE1-79M has inputs available to bypass the
instantaneous reclose attempt and to drive the relay to LOCKOUT inhibiting relay operation at any time.
In addition, a separate input is available which may be used to initiate a pilot reclosing sequence.
The fourth major factor is system coordination. The BE1-79M has outputs available which may be used to
block or enable instantaneous tripping of the circuit breaker and block a transformer's automatic load tap
changer operation during a reclosing sequence.