ABB OTM_C_21D Installation And Operating Instructions Manual page 6

6
A U T O M AT I C T R A N S F E R S W I T C H , O T M _ C _ 2 1 D
No line priority
The switching sequence of OTM_C_21D can be
summarized in following steps:
• An anomaly occurs on the Line 1 (LN1)
• Switching delay Ts, in case of phase-loss, over-
voltage and undervoltage conditions
• Change-over switch (Switch I) to the position 0
• Change-over switch (Switch II) to the position II
LN1
LN2
Switch I status
Switch II status
Figure 3. Automatic Switching Sequences in OTM_C_21D, No line priority
Generator is disabled in no line priority.
Keep generator off in this mode.
Ts
The back switching sequence can be summarized
in the following steps:
• The Line 1 will start the normal functioning
• Change-over switch stays in position II
• An anomaly occurs on the Line 2 (LN2)
• Back switching delay
• Change-over switch (Switch II) to the
position 0
• Change-over switch (Switch I) to the position I
TBs