ERL L-PRO 4000, User Manual

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4 Protection Functions and Specifications
4-24 L-PRO 4000 User Manual D02706R02.30
79 Recloser
The relay provides single-phase tripping and reclosing and 3-phase tripping
and reclosing on the 4000 hardware platform.
The schemes available are user-programmable and consist of the following
user setting options:
• 3-Phase Trip and Reclose Scheme
• 1-Phase/3-Phase Trip and Reclose Scheme
Please note that the user can select only one scheme at a time, although the user
can change the scheme selected by using the setting groups within the setting
software.
3-Phase Trip and Reclose Scheme
This scheme allows the relay to 3 phase trip always (even if the fault is single
phase in nature) and reclose the 3 phases after a period of time. Up to 4 shots
of reclosing is possible, depending upon the user recloser settings. The recloser
logic control is capable of reclosing a single line breaker or two ring bus line
breakers in a variety of sequences. The breaker reclosing sequence refers to the
breakers as lead and follower breakers. The first breaker selected to reclose is
called the lead breaker and the second breaker that is reclosed is called the fol-
lower. The reclosing can be done with or without synch check supervision. The
output matrix is used to determine the inputs and the outputs to the 3-phase 79
recloser. The line breaker (s) is deemed to be open if the current through it is
below 4% of the nominal current rating. (For a 5 A rated relay, this is 0.2 A
rms)
3-Phase Reclose Timers
The lead breaker open interval times are settable for each reclosing shot (T1 to
T4) for the 3-phase recloser. The follow breaker open time interval is common
for each reclosure attempt. This follower breaker reclose time can be set to use
the 79 follower timer TF or the 79 reset timer TD. See L-PRO 4000 Function
Logic Diagram for details.
Lead or Follower Breaker Logic
The recloser setting options allow the lead breaker to be the main or auxiliary
breaker. The recloser automatically selects the follower breaker into the lead
position after the out of service time delay, TC is exceeded. If the follower
breaker is removed from service, after the out of service time delay, TC, there
is no further follower breaker reclose attempts. The breaker status is reset when
the breaker status changes to closed for at least 10 seconds, or if the relay pow-
er supply is toggled Off then On again. A breaker is considered to be closed if
the current measured through it is greater than 0.2 A secondary for a 5 A relay.
(4%
I
n
where I
n
is either 1 A or 5 A)
External Reclose Blocking
The 79 also supports blocking from external devices via the output matrix and
the internal 79 Lockout indication. The user can control the 79 remotely or lo-
cally with external or virtual inputs.