Schweitzer Engineering Laboratories SEL-421-4 - Page 958

5.26
SEL-400 Series Relays Instruction Manual Date Code 20171006
Control
Bay Control Front-Panel Operations
The following example shows the process of changing a three-position discon-
nect from closed in-line to closed to ground. This process requires that you first
open the in-line disconnect before you can close the ground disconnect.
Starting with the one-line diagram in Figure 5.17, highlight the three-position
disconnect and press the ENT pushbutton. If the LOCAL Relay Word bit is
asserted, the control screen shown in Figure 5.16(b) is displayed on the screen.
Note that the only options at this point are to open or close Disconnect SW3.
Therefore, use the Up Arrow or Down Arrow pushbutton to move the highlight box
to the OPEN SW3 position. Then press the ENT pushbutton to open Disconnect
SW3. If Disconnect SW3 successfully opens, the control screen will change as
shown in Figure 5.16(a). Note that the control actions changed so that Discon-
nect SW4 can now be closed. At this point, use the Up Arrow or Down Arrow push-
button to move the highlight box to the
CLOSE SW4 position and press the ENT
pushbutton to close Disconnect SW4. If Disconnect SW4 is successfully closed,
the control screen will change as show in Figure 5.16(c).
Table 5.5 Three-Position Disconnect Switch Control Screen Status and Control Options
State of Disconnects Status Displayed Control Options Displayed Control Actions Available
Disconnect SW3: Open
Disconnect SW4: Open
OPENED
OPENED
SW3
SW4
CLOSE SW3
OPEN
a
CLOSE SW4
CLOSE SW3
NO OPEN CONTROL
CLOSE SW4
Disconnect SW3: Closed
Disconnect SW4: Open
CLOSED
OPENED
SW3
SW4
CLOSE SW3
b
OPEN SW3
CLOSE
CLOSE SW3
OPEN SW3
NO CONTROL for SW4
Disconnect SW3: Open
Disconnect SW4: Closed
OPENED
CLOSED
SW3
SW4
CLOSE
OPEN SW4
CLOSE SW4
c
NO CONTROL for SW3
OPEN SW4
CLOSE SW4
Disconnect SW3: Open
Disconnect SW4: Alarm
OPENED
UNKNOWN
SW3
SW4
CLOSE
OPEN
CLOSE
NO CONTROL for either disconnect
Disconnect SW3: Alarm
Disconnect SW4: Open
UNKNOWN
OPENED
SW3
SW4
CLOSE
OPEN
CLOSE
NO CONTROL for either disconnect
Disconnect SW3: Closed
Disconnect SW4: Alarm
CLOSED
UNKNOWN
SW3
SW4
CLOSE
OPEN
CLOSE
NO CONTROL for either disconnect
Disconnect SW3: Alarm
Disconnect SW4: Closed
UNKNOWN
CLOSED
SW3
SW4
CLOSE
OPEN
CLOSE
NO CONTROL for either disconnect
Disconnect SW3: Closed
Disconnect SW4: Closed
CLOSED
CLOSED
SW3
SW4
CLOSE
OPEN
CLOSE
NO CONTROL for either disconnect
Disconnect SW3: Alarm
Disconnect SW4: Alarm
UNKNOWN
UNKNOWN
SW3
SW4
CLOSE
OPEN
CLOSE
NO CONTROL for either disconnect
a
See Figure 5.16(a) .
b
See Figure 5.16(b) .
c
See Figure 5.16(c) .