Schweitzer Engineering Laboratories SEL-351-5, Instruction Manual

Page: 255 / 706

6.17
Date Code 20070117
Instruction Manual SEL-351-5, -6, -7 Relay
Close and Reclose Logic
Reclosing Relay
Determination of Number of Reclosures (Last Shot)
The number of reclosures is equal to the number of open interval time settings
that precede the first open interval time setting set equal to zero. The “last
shot” value is also equal to the number of reclosures.
In the above example settings, two set open interval times precede open
interval 3 time, which is set to zero (79OI3 = 0.00):
79OI1 = 30.00
79OI2 = 600.00
79OI3 =
0.00
For this example:
Number of reclosures (last shot) = 2 = the number of set open interval
times that precede the first open interval set to zero.
Observe Shot Counter Operation
Observe the reclosing relay shot counter operation, especially during testing,
with the front-panel shot counter screen (accessed via the
{OTHER}
pushbutton). See Functions Unique to the Front-Panel Interface on page 11.6 .
Reset Timer
The reset timer qualifies circuit breaker closure before taking the relay to the
Reset State from the Reclose Cycle State or the Lockout State. Circuit breaker
status is determined by the SEL
OGIC
control equation setting 52A. (See Close
Logic on page 6.2 for more discussion on SEL
OGIC
control equation setting
52A. Also see Optoisolated Inputs on page 7.2 for more discussion on
SEL
OGIC
control equation setting 52A.)
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 Sequence
Coordination Setting (79SEQ) on page 6.26 ].
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 Figure 6.1 ).
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
Changes on page 6.14 ).
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.