Generator, ATS & Emergency Power Sequence Simulator

Step through the full utility-loss-to-generator-transfer sequence — start delay, warm-up, ATS transfer, re-transfer, cooldown — with configurable timing parameters, a live one-line diagram, state machine view, and event timeline.

AVAILABLEAUTOMATED CHECKS ONLYCONCEPTUAL ONLYINTERMEDIATEWHAT DO THESE STATUSES MEAN?

FULL ATS SEQUENCELIVE ONE-LINESTATE MACHINE VIEWCONFIGURABLE TIMING

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Overview

Generator and ATS systems are one of the most critical and least-understood parts of facility power infrastructure. Engineers design them, technicians commission them, and facility managers operate them — but the detailed sequence of events from utility loss to stable generator supply and back is often tribal knowledge. This simulator makes the full sequence visible and configurable: set start delay, generator warm-up time, ATS transfer delay, re-transfer delay, and cooldown time, then initiate a utility outage and watch the system step through each state in real time. The One-Line tab shows a live single-line diagram with the utility source, ATS, generator, and loads, with active paths highlighted at each sequence step. The State tab shows the sequence state machine, making it clear which state is active and what conditions trigger each transition. The Timeline tab displays a chronological breakdown of the sequence showing exactly how long each load was without power. The Scenario tab provides quick-access preset sequences. Controls include load shedding percentage. Designed for engineers involved in emergency power system design, commissioning, and testing.

App preview

A live look at the app you'll launch — every control on the left drives the visualizations on the right in real time.

Inside the lab

Example data — not a real field report

Overview tab with sequence summary and system status — Overview — top-level dashboard showing the current system state, a quick summary of the utility-to-generator sequence, and the parameters currently loaded (start delay, warm-up, transfer delay, cooldown). Great starting point before triggering an outage.

One-Line tab showing utility, ATS, generator, and loads with active path highlighted — One-Line — live single-line diagram with utility source, ATS, generator, and loads. Active current paths highlight in real time as the sequence progresses, so you can see exactly which source is feeding the loads at every moment of the transfer.

State Machine tab showing sequence states and the currently active state — State Machine — the full sequence state diagram (Normal → Utility Loss → Start Delay → Warm-Up → Transfer → On Generator → Re-Transfer → Cooldown → Normal). The active state is highlighted and the transition conditions between states are labeled.

Timeline tab with chronological event breakdown and outage durations by load type — Timeline — chronological event log with elapsed time for every step and a breakdown of load outage duration by load type (life-safety, critical, non-critical). Makes it easy to see which loads met NEC 700 / NFPA 110 timing targets and which didn't.

Scenario Lab tab with preset transfer scenarios — Scenario Lab — one-click preset scenarios: full power outage sequence, generator fails to start, generator bad voltage/frequency, full cycle with retransfer, overloaded generator with load shedding, and reset to defaults. Fastest way to explore failure modes.

Learn tab with generator/ATS theory and NEC 700 / NFPA 110 references — Learn — plain-language reference cards covering ATS types, why re-transfer uses a longer delay than transfer, generator warm-up and cooldown purpose, load shedding logic, and the NEC 700 / NFPA 110 timing requirements every emergency-power designer should know.

What you'll do

01List the sequence of states from utility loss to stable generator supply and identify timing requirements for each
02Explain the purpose of start delay, warm-up, ATS transfer delay, re-transfer delay, and cooldown periods
03Interpret a state machine diagram for a generator/ATS system and identify trigger conditions for each transition
04Determine total load outage duration for critical versus non-critical loads based on transfer timing
05Explain why re-transfer to utility uses a longer delay than initial transfer to generator
06Identify NEC 700 and NFPA 110 timing requirements relevant to emergency and standby systems

What this lab is not

Not a design document, stamped calculation, or approval record.
Not a substitute for engineering analysis by a licensed professional.
Not connected to live equipment and not a safety device.

Calculation basis

Results are computed from first-principles circuit relationships using the values you enter.

Simplifying assumptions are stated in the lab itself; where a model is intentionally conceptual, the lab says so rather than implying study-grade accuracy.

Standards basis: Conceptual only. Validation state: Automated checks only (last checked 2026-08-15).