Schweitzer Engineering Laboratories SEL-351A - Figure 5.2 Minimum Trip Duration Timer Operation (See Bottom of Figure 5.1)

5.3
Date Code 20080213 Instruction Manual SEL-351A Relay
Trip and Target Logic
Trip Logic
Figure 5.2 Minimum Trip Duration Timer Operation (See Bottom of
Figure 5.1)
Relay Word bit OC asserts for execution of the OPEN command. See OPE
Command (Open Breaker) on page 10.35 for more information on the OPEN
command. More discussion follows later on the factory settings for setting TR.
Make the following setting to supervise the OPEN command with
optoisolated input IN105:
TR = … + OC * IN105
With this setting, the OPEN command can provide a trip only if optoisolated
input IN105 is asserted. This is just one OPEN command supervision
example—many variations are possible.
To prevent the execution of the OPEN command from initiating reclosing,
Relay Word bit OC is entered in the SEL
OGIC control equation setting 79DTL
(Drive-to-Lockout) in the factory settings. See the Note in the Lockout State
discussion, following Table 6.1.
A COMM target LED option for the OPEN command is discussed in the Front-
Panel Target LEDS on page 5.10.
Unlatch Trip
Once Relay Word bit TRIP is asserted to logical 1, it remains asserted at
logical 1 until all the following conditions come true:
➤ Minimum Trip Duration Timer stops timing (logic output of the
TDURD timer goes to logical 0)
➤ Output of OR-1 gate deasserts to logical 0
➤ One of the following occurs:
➢ SELOGIC control equation setting ULTR asserts to
logical 1,
➢ The front-panel {TARGET RESET} pushbutton is pressed,
➢ Or the TAR R (Target Reset) command (or the
equivalent Fast Operate Reset command) is executed
via the serial port.
Example output of
OR-1 (input into
Minimum Trip
Duration Timer and
OR-2)
Resultant logic
output of Minimum
Trip Duration Timer
(input into OR-2)
OR-combination of
above two logic
traces (inputs into
OR-2 to drive Relay
Word bit TRIP)
Rising-edge
input occurring
when the
Minimum
Trip Duration
Timer is reset
TDURD TDURD TDURD
NOTE: The OPEN (OC) command is
not embedded in the trip logic. It is
included in the factory SEL
OGIC
control equation settings:
TR = … + OC
Courtesy of NationalSwitchgear.com