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4.69
Date Code 20081022
Instruction Manual
SEL-787 Relay
Protection and Logic Functions
Trip/Close Logic
Figure 4.44
Trip Logic
TDURD Minimum Trip Time
This timer establishes the minimum time duration for which the TRIP Relay
Word bits assert. This is a rising-edge initiated timer.
Trips initiated by TR
m
(
m
= 1, 2, XFMR) Relay Word bits (includes
OPEN
command from front-panel and serial ports) are maintained for at least the
duration of the minimum trip duration time (TDURD) setting.
TR Trip Conditions SEL
OGIC
Control Equations
There are three trip logic equations within the SEL-787. They are designed to
operate when
SEL
OGIC
control equation trip variable setting TR
m
is asserted
(
m
= 1, 2, XFMR), and to unlatch when
SEL
OGIC
control equation setting
0
TDURD
Serial Port
Command TAR R
TARGET RESET
Pushbutton
TRGTR
Reset
TRIP LED
RWB
TRIP1
Trigger
Events
Unlatch Trip
Comm.
Target Reset
RSTTRGT
ULTRIP1
TR1
Relay
Word
Bits
SEL
OGIC
Settings
0
TDURD
RWB
TRIP2
Trigger
Events
Unlatch Trip
ULTRIP2
TR2
0
TDURD
RWB
TRIPXFMR
Trigger
Events
Unlatch Trip
ULTRXFMR
TRXFMR
TRIP1
TRIP2
TRIXFMR
RWB
TRIP
Summary of Contents for SEL-787
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