Schweitzer Engineering Laboratories SEL-351 - Selector Switch Now Rests on Position REMOTE

7-28 Inputs, Outputs, Timers, and Other Control Logic Date Code 20001006
SEL-351 Instruction Manual
Selector Switch Starts Out in Position 3
Refer to Table 7.7 and Figure 7.24.
If the selector switch is in position 3 in Figure 7.23, setting Group 3 is the active setting group
(Relay Word bit SG3 = logical 1). Inputs IN1 and IN2 are energized and IN3 is deenergized:
SS3 = !IN3 * IN2 * IN1 = NOT(IN3) * IN2 * IN1
= NOT(logical 0) * logical 1 * logical 1 = logical 1
To get from the position 3 to position 5 on the selector switch, the switch passes through the
position 4. The switch is only briefly in position 4:
SS4 = IN3 * !IN2 * !IN1 = IN3 * NOT(IN2) * NOT(IN1)
= logical 1 * NOT(logical 0) * NOT(logical 0) = logical 1
but not long enough to be qualified by time setting TGR in order to change the active setting group
to setting Group 4. For such a rotating selector switch application, qualifying time setting TGR is
typically set at 180 to 300 cycles. Set TGR long enough to allow the selector switch to pass
through intermediate positions without changing the active setting group, until the switch rests on
the desired setting group position.
Selector Switch Switched to Position 5
Refer to Figure 7.24.
If the selector switch is rested on position 5 in Figure 7.23, setting Group 5 becomes the active
setting group (after qualifying time setting TGR; Relay Word bit SG5 = logical 1). Inputs IN1 and
IN3 are energized and IN2 is deenergized:
SS5 = IN3 * !IN2 * IN1 = IN3 * NOT(IN2) * IN1
= logical 1 * NOT(logical 0) * logical 1 = logical 1
To get from position 5 to position REMOTE on the selector switch, the switch passes through the
positions 4, 3, 2, and 1. The switch is only briefly in the these positions, but not long enough to be
qualified by time setting TGR in order to change the active setting group to any one of these setting
groups.
Selector Switch Now Rests on Position REMOTE
Refer to Figure 7.24.
If the selector switch is rested on position REMOTE in Figure 7.21, all inputs IN1, IN2, and IN3
are deenergized and all settings SS1 through SS6 in Table 7.7 are at logical 0. The last active
setting group (Group 5 in this example) remains the active setting group (Relay Word bit SG5 =
logical 1).
With settings SS1 through SS6 all at logical 0, the serial port GROUP command or the front-panel
GROUP pushbutton can be used to switch the active setting group from Group 5, in this example,
to another desired setting group.
Courtesy of NationalSwitchgear.com