Otm_C_21D Switching Sequence; Line 1 Priority (Default Mode); No Line Priority - ABB OTM C 21D Installation And Operating Instructions Manual

2.2 OTM_C_21D switching sequence

2.2.1 Line 1 Priority (default mode)

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, overvoltage and undervoltage conditions
• Generator start, immediate start generator in case of black-out, in case of phase-loss,
overvoltage or undervoltage after switching delay Ts. (If Generator mode is selected)
• Change-over switch (Switch I) to the position 0
• Change-over switch (Switch II) to the position II
And the back switching sequence can be summarized in the following steps:
• The Line 1 will start the normal functioningl Back switching delay Tbs
• Change-over switch (Switch II) to the position 0
• Change-over switch (Switch I) to the position I
• Generator stop delay Gs
• Generator stop
Figure 2. Automatic Switching Sequences in OTM_C_21D, Line 1 priority

2.2.2 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, overvoltage and undervoltage conditions
• Change-over switch (Switch I) to the position 0
• Change-over switch (Switch II) to the position II
And 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
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1SCC303015M0201 l ABB Installation and operating instructions, 34OTM_C_21D rev. B
2. Product overview