5.4
SEL-400 Series Relays Instruction Manual Date Code 20171006
Control
Disconnect Logic
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
89CCMm and 89OCMm 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 89CCMm or 89OCMm cannot assert.
89CC
m
, 89OC
m
The 89CLOSE command or Fast Operate disconnect close message, pulses
Relay Word bit 89CCm for one-quarter cycle. The 89OPEN command or Fast
Operate disconnect open message, pulses Relay Word bit 89OCm 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
89CSTm and 89OSTm 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 89CLSm and 89OPEm Relay Word bits are used in SELOGIC output equa-
tions to perform close and open disconnect switch operations.
Disconnect Switch Close and Open Control Logic Processing
Figure 5.1 shows the Disconnect Switch Close Logic and Figure 5.2 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 SELOGIC equations 89CRSm and 89ORSm set to the default settings
(include Relay Word bits 89CSIm and 89OSIm), the open and close signals
remain asserted for the time settings of the Close and Open Seal-In Timers,
89CSTm and 89OSTm.
If the 89OBLm SEL
OGIC control equation and the 89OPEm and the LOCAL
Relay Word bits are deasserted, then any of the relay close disconnect operate
methods can assert Relay Word bit 89CLSm, and initiate the Close Seal-In Timer,
89CSTm. Enter Relay Word bit 89CLSm into a SEL
OGIC output equation to drive
the motor of the disconnect.
Set the Close Seal-In Timer, 89CSTm, long enough to keep Relay Word bit
89CLSm asserted long enough to complete the disconnect operation.
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