4.33
Date Code 20080918 Instruction Manual SEL-749M Relay
Protection and Logic Functions
I/O Configuration
You can assign any control input to the SELOGIC control equation BLKPROT.
One or more protective functions listed in Table 4.30 can be inhibited when
the BLKPROT control input asserts.
During certain operational phases, when the level (e.g., motor current) differs
from normal values, selected functions are completely disabled as long as the
control input is asserted. For operational phases such as those listed below,
you could have no warning, no trip or reset, and tripping delays that begin to
run only after the function is reenabled:
➤ During starting (earth fault and short-circuit protection)
➤ At no-load (protection against asymmetry and underload)
➤ During brief overload phases (high overload/jam)
➤ During commissioning and fault location (localizing the source
of the trouble)
Trip/Close Logic
NOTE: The factory-default
assignment of the Relay Word bit TRIP
is the output OUT103. See Tab le 4. 37 for
the output contacts settings.
The SEL-749M 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 4.20 illustrates the tripping logic.
Table 4.31 Trip and Close Logic Settings
Setting Prompt Setting Range Setting Name := Factory Default
MIN TRIP TIME 0.0–400.0 sec TDURD := 0.5
TRIP EQUATION SV TR := 49T OR LOSSTRIP OR JAMTRIP
OR 46UBT OR 50P1T OR 50G1T OR
59P1T OR 47T OR 55T OR SPDSTR OR
50N1T OR SMTRIP OR 81D1T OR
81D2T OR SV01T
REMOTE TRIP EQN SV REMTRIP := 0
UNLATCH TRIP EQN SV ULTRIP := 0
CONTACTOR STATUS SV 52A := NOT IN101
Courtesy of NationalSwitchgear.com
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