ABB TruONE ATS, Installation And Operating Instruction

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2.5 Description of basic functionality
2.5.1 Switching sequence / Automatic
2.5.1.1 Source 1 Priority
(Source 2 = Generator)
Switching sequence summary:
• An anomaly occurs on the source 1
• Override momentary S1 outage delay
• Generator start
• Source 2 OK
• Transfer from S1 to S2 delay
• Pre-transfer signal on
• Load shed signal on
• Pre-transfer S1 to S2 delay
• Load shed delay
• Transfer switch to the position O (only
with delayed transition I-O-II type and
at least one phase exists in source 1)
• Center-Off delay (only with delayed
transition I-O-II type, delay is zero when
all phases are missing in source 1)
• Transfer switch to the position II
(source 2)
• Post-transfer S1 to S2 delay
• Pre-transfer signal off
Retransfer sequence summary:
• The source 1 is restored
• Transfer from S2 to S1 delay
• Pre-transfer signal on
• Pre-transfer S2 to S1 delay
• Transfer switch to the position O (only
with delayed transition I-O-II type)
• Center-off delay (only with Delayed tran-
sition I - O - II type)
• Transfer switch to the position I
(source 1)
• Load shed signal off
• Generator stop delay
• Post-transfer S2 to S1 delay
• Pre-transfer signal off
• Generator stop
• Source 2 off