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5.4
SEL-400 Series Relays
Instruction Manual
Date Code 20171006
Control
Disconnect Logic
CAUTION
switch operations; this disconnect operate method is not supervised by the
breaker jumper or appropriate relay access levels as is the case with other discon-
nect operation methods.
89CCM
m
, 89OCM
m
89CCM
m
and 89OCM
m
Relay Word bits pulse for one-quarter cycle when close
or open disconnect operations are initiated from the one-line diagram on the
front-panel screen. If the LOCAL Relay Word bit is not asserted, then Relay
Word bits 89CCM
m
or 89OCM
m
cannot assert.
89CC
m
, 89OC
m
The
89CLOSE
command or Fast Operate disconnect close message, pulses
Relay Word bit 89CC
m
for one-quarter cycle. The
89OPEN
command or Fast
Operate disconnect open message, pulses Relay Word bit 89OC
m
for one-quarter
cycle. The LOCAL Relay Word bit must be deasserted for a disconnect switch
operation to be initiated by a Fast Operate message or
89CLOSE
and
89OPEN
commands.
Disconnect Seal-In Timer Settings
89CST
m
, 89OST
m
89CST
m
and 89OST
m
settings are for defining the time required for the discon-
nect switch to complete a close or open operation.
Disconnect Switch Close and Open Control Logic Output
89CLS
m
, 89OPE
m
The 89CLS
m
and 89OPE
m
Relay Word bits are used in SEL
OGIC
output equa-
tions to perform close and open disconnect switch operations.
Disconnect Switch Close and Open Control Logic Processing
shows the Disconnect Switch Close Logic and
shows the
Disconnect Switch Open Logic.
Some motor-operated disconnect switches have their own seal-in circuits to seal
the closing and opening signals in. Other motor-operated disconnect switches,
however, require external sealed-in circuits to maintain the closing and opening
signals for the duration of the disconnect operation.
The outputs in the relay are not
designed to break the coil current in
the disconnect motor. An auxiliary
contact with adequate current inter-
rupting capacity must clear the coil
current in the disconnect motor
before the output on the relay opens.
Failure to observe this safeguard
could result in damage to the relay
output contacts.
With SEL
OGIC
equations 89CRS
m
and 89ORS
m
set to the default settings
(include Relay Word bits 89CSI
m
and 89OSI
m
), the open and close signals
remain asserted for the time settings of the Close and Open Seal-In Timers,
89CST
m
and 89OST
m
.
If the 89OBL
m
SEL
OGIC
control equation and the 89OPE
m
and the LOCAL
Relay Word bits are deasserted, then any of the relay close disconnect operate
methods can assert Relay Word bit 89CLS
m
, and initiate the Close Seal-In Timer,
89CST
m
. Enter Relay Word bit 89CLS
m
into a SEL
OGIC
output equation to drive
the motor of the disconnect.
Set the Close Seal-In Timer, 89CST
m
, long enough to keep Relay Word bit
89CLS
m
asserted long enough to complete the disconnect operation.
Summary of Contents for SEL-421-4
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