Date Code 20011205
Trip and Target Logic
5-3
SEL-311A Instruction Manual
Figure 5.2: Minimum Trip Duration Timer Operation (See Bottom of Figure 5.1)
The OPEN command is included in the trip logic in the factory settings:
TR = … + OC
Relay Word bit OC asserts for execution of the OPEN Command. See
OPE Command (Open
Breaker)
in
Section 10: Serial Port Communications and Commands
for more information on
the OPEN Command. More discussion follows later on the factory settings for setting TR.
If a user wants to supervise the OPEN command with optoisolated input IN105, the following
setting is made:
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.
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 in Figure 5.1 deasserts to logical 0
·
One of the following occurs:
-
SEL
OGIC
control equation setting ULTR asserts to logical 1,
-
The front-panel TARGET RESET button is pressed,
-
Or the
TAR R
(Target Reset) command is executed via the serial port.
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