5.25
Date Code 20171006 Instruction Manual SEL-400 Series Relays
Control
Bay Control Front-Panel Operations
Similar to the standard disconnect, if a three-position disconnect is highlighted
on the one-line diagram and the ENT pushbutton is pressed, a control screen is dis-
played. The control screen shows the present status of the disconnect based on
the disconnect status bits (89CLm, 89OPNm, 89OIPm, and 89ALm) from both
disconnects that make up the three-position disconnect. The status is shown via
the disconnect symbol and the status labels as shown in Figure 5.16(a).
Figure 5.16(a) shows the control screen of a three-position disconnect with both
disconnects in the open state. Figure 5.16(b) shows the control screen of a three-
position disconnect with the in-line disconnect closed and the ground disconnect
open. Likewise, Figure 5.16(c) shows the control screen of a three-position dis-
connect with the in-line disconnect open and the ground disconnect closed.
The three-position disconnect logic is identical to two standard disconnects, but
control actions are limited as shown in Table 5.5. A control action is only avail-
able if the disconnect name is listed next to the action as indicated in the Control
Options Displayed column. For example, in the second set of control actions,
where Disconnect SW3 is closed and Disconnect SW4 is open, the only control
actions available are to open or close Disconnect SW3. Figure 5.16(b) shows the
control screen for this condition.
Figure 5.16 Three-Position Disconnect Control Screens
BAYNAME
OPEN
CLOSE SW3
CLOSE SW4
OPENED SW3
OPENED SW4
SW3
SW4
PRESS TO ACTIVATE
In-Line Disconnect
Ground (perpendicular) Disconnect
BAYNAME
OPEN SW4
CLOSE
CLOSE SW4
OPENED SW3
CLOSED SW4
SW3
SW4
PRESS TO ACTIVATE
BAYNAME
OPEN SW3
CLOSE SW3
CLOSE
CLOSED SW3
OPENED SW4
SW3
SW4
PRESS TO ACTIVATE
Status of the in-line
disconnect SW3
Status of the ground
disconnect SW4
(a) Three-Position Disconnect Open
(b) Three-Position Disconnect Closed In-Line (c) Three-Position Disconnect Closed to Ground
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