5.8
SEL-400 Series Relays Instruction Manual Date Code 20171006
Control
Disconnect Logic
the 89CSTm seal-in timer, you can ensure retention of the close signal until the
disconnect switch closes completely. If there is no complete disconnect switch
operation during the time 89ALPm defines, the relay asserts Relay Word bit
89ALm and reports that the disconnect switch is in an undetermined state.
The scenario in which both 89AMm and 89BMm are asserted simultaneously
would occur on a rare disconnect switch failure or a short-circuited auxiliary con-
tact wire connection. When this condition occurs for 89ALPm seconds, the
89ALm alarm status output will assert.
Disconnect Switch Close and Open Immobility Timer Logic
The Close and Open Immobility Timer Logic detects when a disconnect opera-
tion failed to initiate.
Close and Open Immobility Timer Logic Inputs
LOCAL
The LOCAL Relay Word bit supervises local disconnect control and is based on
the LOCAL SEL
OGIC control equation in the Bay settings class. Disconnect
switch operations from the front panel are possible when the LOCAL Relay
Word bit is asserted, in other words, the LOCAL Relay Word bit prevents control
from the HMI without proper supervision.
89CBL
m
, 89OBL
m
The 89CBLm and 89OBLm SELOGIC control equations provide an alternative
customizable method for blocking the initiation of a disconnect switch open or
close command, respectively.
Figure 5.4 Close Immobility Timer Logic
Close Immobility Timer
89CITm
60
CYC
89CIRm
(default setting:
NOT 89OPNm)
Relay
Word
Bits
* SELOGIC control equation
89CIMm
(Reset)
89CBLm
89OPEm
89CCMm
89CCm (ASCII)
*89CCNm (k – 1/8 cyc.)
*89CCNm (k)
*LOCAL
Figure 5.5 Open Immobility Timer Logic
Open Immobility Timer
89OITm
60
CYC
89OIRm
(default setting:
NOT 89CLm)
Relay
Word
Bits
89OIMm
(Reset)
89OBLm
89CLSm
89OCMm
89OCm (ASCII)
*89OCNm (k – 1/8 cyc.)
*89OCNm (k)
*LOCAL
* SEL
OGIC control equation
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