Sel 411L - Page 766

P.12.6
SEL-411L Relay Protection Manual Date Code 20151029
Bay Control
Disconnect Logic
Disconnect switch status and alarm logic in Figure 12.3 generates Relay Word
bit 89ALm. When Relay Word bit 89ALm asserts, a disconnect alarm
condition exists. The 89ALm Relay Word bit ensures that the close or open
signal does not remain asserted when a disconnect switch alarm condition
exists. When Relay Word bit 89ALm asserts or the seal-in timer expires, the
89CLSm or 89OPEm signals deassert.
When a close operation is inadvertently initiated with the disconnect switch
already closed, and the 89CRSm SEL
OGIC equation is set as defaulted
(89CLm OR 89CSIm), the asserted 89CLm Relay Word bit (close status) will
block the seal-in circuit before the timer expires. This will deassert the
89CLSm Relay Word bit, which drives the disconnect switch motor. In this
way, 89CLSm asserts for only one processing interval (1/4 cycle).
If an OPEN command was sent within the 89CSIm time, an open and close
signal could be sent to the disconnect switch at the same time. The 89CLSm
Relay Word bit input to the disconnect switch open logic guarantees that
OPEN and CLOSE commands are not transmitted to the disconnect switch
simultaneously. When the 89CLSm Relay Word bit deasserts, then an open
command can be performed. The 89OBLm SEL
OGIC control equation
provides an additional customizable method for blocking the initiation of an
OPEN command. The Relay Word bit 89OPEm, and 89CBLm inputs to the
disconnect switch close logic serves the same purpose.
Disconnect Switch
Status and Alarm
Logic
Introduction
The disconnect switch auxiliary contacts are inputs to the disconnect switch
status and alarm logic as shown in Figure 12.3. SEL
OGIC control equation
89AMm is the input for the normally open a auxiliary contact, and SEL
OGIC
control equation 89BMm is the input for the normally closed b auxiliary
contact. For the status and alarm logic to function correctly, wire the a and b
contacts each to separate inputs on the relay. Depending on the one-line
diagram selected, as many as 10 disconnect switches are supported. This
means that for 10 disconnect switches, you should wire 20 inputs to the
disconnect switch auxiliary contacts. When ordering the relay, consider the
number of inputs required for the bay configuration being controlled. The
number of auxiliary contacts for some bay configurations may require that the
relay be configured with additional I/O boards; see the relay Model Option
Table for ordering options.
Disconnect operations are possible with only one auxiliary contact input, but
with this implementation the status and alarm logic will not provide accurate
Alarm, Operation in Progress, or Bus-Zone protection reporting. When only
one auxiliary contact is available for input, set one SEL
OGIC control equation
to the available auxiliary contact input and invert the other SEL
OGIC control
equation:
89AMm := IN202
89BMm := NOT IN202