ABB OMD800 - Manual Back Switching Mode

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AUTOMATIC CONTROL UNIT, OMD800
Figure 3.4 Automatic Switching Sequence, Manual back switching mode
Ts: Switching delay, Tt: Delay on transfer, Ds: Dead band I to II, TBs: Back switching delay
Ts Tt Ds TBs Ds
LINE 1
LINE 2
Switch I status
Switch II status
Gen. start
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3.1.4 Manual back switching mode
The switching sequence of OMD800 can be summarized in following steps:
An anomaly occurs on the Line 1
Switching delay
Generator start
Delay on transfer
If Pre-transfer signal active: Pre-trasnfer signal output on,
Pre-transfer I to II delay
Change-over switch (Switch I) to the position O
Dead band I to II delay
Change-over switch (Switch II) to the position II
If Pre-transfer signal active: Pre-transfer signal output off
And the back switching sequence can be summarized in the following steps:
The Line 1 will start the normal functioning
Back switching delay
Change-over switch stays in position II
An anomaly occurs on the Line 2
If Pre-transfer signal active: Pre-transfer output on,
Pre-transfer II to I delay
Change-over switch (Switch II) to the position O
If Pre-transfer signal active: Pre-transfer output off
The Line 2 will start the normal functioning
Dead band I to II delay
Change-over switch (Switch II) to the position II