4.65
Date Code 20100129
Instruction Manual
SEL-751A Relay
Protection and Logic Functions
Reclose Logic
Setting 79RSD
Qualifies closures when the relay is in the Reclose Cycle State. These closures
are usually automatic reclosures resulting from open interval time-out.
It is also the reset time used in sequence coordination schemes [see
Coordination Setting (79SEQ) on page 4.72
].
Setting 79RSLD
Qualifies closures when the relay is in the Lockout State. These closures are
usually manual closures. These manual closures can originate external to the
relay, via the
CLOSE
command, or via the SEL
OGIC
control equation setting
CL (see
).
Setting 79RSLD is also the reset timer used when the relay powers up, has
individual settings changed for the active setting group, or the active setting
group is changed (see
Reclosing Relay States and Settings/Setting Group
Typically, setting 79RSLD is set less than setting 79RSD. Setting 79RSLD
emulates reclosing relays with motor-driven timers that have a relatively short
reset time from the lockout position to the reset position.
The 79RSD and 79RSLD settings are set independently (setting 79RSLD can
even be set greater than setting 79RSD, if desired). SEL
OGIC
control equation
setting 79BRS (block reset timing) can be set to control reset timing [see
Block Reset Timing Setting (79BRS) on page 4.71
Monitoring Open Interval and Reset Timing
Open interval and reset timing can be monitored with the following Relay
Word bits:
If the open interval timer is actively timing, OPTMN asserts to logical 1.
When the relay is not timing on an open interval (e.g., it is in the Reset State or
in the Lockout State), OPTMN deasserts to logical 0. The relay can only time
on an open interval when it is in the Reclose Cycle State, but just because the
relay is in the Reclose Cycle State does not necessarily mean the relay is
timing on an open interval. The relay only times on an open interval after
successful reclose initiation and no stall conditions are present [see
and Stall Open Interval Timing Settings (79SKP and 79STL, Respectively) on
page 4.69
If the reset timer is actively timing, RSTMN asserts to logical 1. If the reset
timer is not timing, RSTMN deasserts to logical 0. See
.
Relay Word Bits
Definition
OPTMN
Indicates that the open interval timer is
actively
timing
RSTMN
Indicates that the reset timer is
actively
timing
Summary of Contents for 751A
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