Schweitzer Engineering Laboratories SEL-421-4, Instruction Manual

Page: 952 / 1518

5.20
SEL-400 Series Relays Instruction Manual Date Code 20171006
Control
Bay Control Front-Panel Operations
If Relay Word bit 89CCM1 asserts after you press the ENT key, the relay displays
the screen with the caption
CLOSE COMMAND ISSUED
in Figure 5.12(c) for three
seconds. While the disconnect operation is in progress, the relay displays the
screen with the caption
IN PROGRESS
in Figure 5.13(a) and the disconnect sym-
bol alternately displays the present state symbol and the opposite state symbol. If
another disconnect operation attempt is made while a disconnect operation is in
progress, the relay displays the screen with the caption
*NOT ALLOWED*
in
Figure 5.13(b) for three seconds and then the relay returns to the screen in
Figure 5.13(a) .
If Relay Word bit 89CCM1 does not assert, the relay displays the
*NOT ALLOWED*
error message shown in Figure 5.12(d) for three seconds and then displays again
the screen in Figure 5.12(b) .
When Relay Word bit 89CCMD1 asserts, the Close Immobility Timer starts. If
Relay Word bit 89CCMD1 asserts, two scenarios are possible: the disconnect
fails to close, or the disconnect closes successfully. In the case of a successful
close operation, the relay displays the screen in
Figure 5.14(b) .
Failing to close also has two possible scenarios: the disconnect starts to move, but
does not complete the operation, or the disconnect switch operation does not initiate.
When Relay Word bit 89OPN1 deasserts, the Close Immobility timer resets, indi-
cating that the disconnect switch has started to move. If Relay Word bit 89CL1
fails to assert in the expected operation time, the disconnect switch has failed to
complete the close operation in the expected time. Failure of the 89CL1 Relay
Word bit to assert in the expected disconnect switch operation time causes the
89AL1 Relay Word bit to assert. When Relay Word bit 89AL1 asserts, the relay
displays the screen
Figure 5.14(a) (see Disconnect Switch Status and Alarm
Logic on page 5.5 ).
If Relay Word bit 89OPN1 fails to deassert before the Close Immobility Timer
expires, Relay Word bit 89ICM1 asserts and the relay displays the screen with the
caption
STATUS UNKNOWN
in Figure 5.14(a) . See Disconnect Switch Close and
Open Immobility Timer Logic on page 5.8 for more information regarding the
close and open immobility timer logic.
When the disconnect operation completes successfully, the relay displays the
screen in
Figure 5.14(b) until the front-panel timer times out or the
ESC
pushbut-
ton is pressed.