ATS & Main-Tie-Main Control Schemes

What this covers

• Main-Tie-Main (3-in-2) — open, closed and fast transition with bus dead-time grading and priority return.
• Multi-source and multi-tie logic — 4-in-2 and 3-in-1 arrangements across utility feeds, standby generators and segmented essential/non-essential busbars.
• Synchronism check (ANSI 25) and parallel-transition blocking, so two sources that must never be paralleled cannot be.
• Generator sequencing — start/stop scheduling, run-on and cool-down cycles, and load acceptance steps.
• Pre-transfer load tripping — shedding non-essential feeders before the bus-tie closes, so a single transformer or generator is not overloaded on transfer.
• Control circuit integrity — anti-pumping, trip circuit supervision, DC supply monitoring and breaker position discrepancy alarms.
• Operator interface — dynamic single-line mimic, source health status, auto/manual override, adjustable transfer timers and alarm history.

What you receive

• TIA Portal application (.zap archive) in structured LAD and SCL with IEC-compliant tagging
• KTP-series HMI project with the mimic, override and timer screens
• Control philosophy document and cause-and-effect / trip matrix
• S7-PLCSIM simulation record covering every transfer case and failure mode
• PLC I/O assignment schedule cross-referenced to the panel schematics

Standards and references

Transfer schemes are engineered to IEC 60947-6-1 for transfer switching equipment and IEC 61131-3 for control logic, with synchronism check following the applicable IEEE C37 practice and the project's transfer timing and interlocking specification.