Schweitzer Engineering Laboratories SEL-701 - Stop;Trip Logic

Date Code 20010719 701 Motor Protection Relay
SELOGIC
®
Control Equations & Relay Logic
Stop/Trip Logic
B.19
Stop/Trip Logic
The SEL-701 Relay tripping logic is designed to trip or stop motors energized
through circuit breakers or contactors. The relay logic lets you define the conditions
that cause a trip, the conditions that unlatch the trip, and the performance of the relay
output contact motor contactor or breaker. Figure B.6 on page B.20 illustrates the
tripping logic.
Initiate Trip
The SEL-701 Relay Trip Logic offers three ways to stop the protected motor:
 TRIP SEL
OGIC control equation.
 Front panel, Modbus
®
, or serial port STOP command.
 Trips generated by the remote bit function.
Any of the three of these conditions will trigger an event report. The relay controls
the TRIP output contacts depending on the Enable Trip Contact Fail-Safe setting. Refer
to Figure B.6.
Set the TRIP SELOGIC control equation to include an OR-combination of all the
enabled protection element Relay Word bits that you want to cause the relay to trip.
Use the factory default setting as a guideline.
Unlatch Trip
Following a fault, the trip signal is maintained until all of the following conditions
are true:
 Minimum Trip Duration Time (TDURD) passes.
 The TRIP SEL
OGIC control equation result deasserts to logical 0.
 All the motor lockout functions, described below, deassert to
logical 0.
 One of the following occurs:
 Unlatch Trip SEL
OGIC control equation setting ULTRIP asserts
to logical 1.
 A rising edge of the TARR SEL
OGIC control equation is
detected.
 The front-panel Trip/Target Reset menu item is selected.
 The serial port TARGET R (Target Reset) command is
executed.
 The Modbus Reset control command is executed.
 An Emergency Restart command is executed or the EMRSTR
SEL
OGIC control equation setting asserts to logical 1.