Transfer switch delay in seconds between a utility power outage and standby generator ignition

An automatic transfer switch introduces a programmed 2- to 10-second engine start delay before initiating standby generator ignition to verify total utility loss and prevent nuisance starts during momentary grid flickers.

Grid power interruptions frequently involve transient voltage sags or utility recloser operations lasting under three seconds. Rapid, uncoordinated generator starts during momentary utility drops cause unnecessary engine wear, fuel consumption, and battery discharge across residential and commercial standby installations.

If you only do one thing: Set the automatic transfer switch (ATS) time delay engine start timer between 3 and 5 seconds to bypass transient line faults without delaying backup power delivery.

1. Utility Outage Verification (2 to 10 Seconds): The Automatic Transfer Switch (ATS) monitors line voltage; when utility power drops below 80% to 85% of nominal voltage, the Time Delay Engine Start (TDES) timer runs for 2 to 10 seconds before signaling the engine control module.
2. Cranking and Ignition Sequence (3 to 6 Seconds): Once the start contact closes, the generator starter engages for a 3- to 6-second cranking cycle using 12-volt direct-current (DC) battery power to ignite the fuel supply, whether natural gas, propane, or diesel.
3. Engine Warm-Up and Stabilization (5 to 15 Seconds): The engine accelerates to operating speed (1,800 or 3,600 RPM) while the automatic voltage regulator and governor stabilize electrical output to 60 Hertz and nominal line voltage before taking on mechanical load.
4. Switching Mechanism Activation (Under 1 Second): Once generator power reaches 90% of rated voltage and frequency, the transfer mechanism mechanically disconnects the utility supply and closes the emergency power contacts within 50 to 100 milliseconds.
5. Total Power Restoration Cycle (10 to 30 Seconds): Standard National Electrical Code (NEC) Article 702 optional standby installations deliver backup electricity to distribution panels within 10 to 20 seconds total, satisfying residential comfort demands while protecting sensitive motor loads.

• Watch out for: Setting start delays below two seconds, which triggers repetitive false starts during utility recloser cycles and quickly drains starter batteries.
• Watch out for: Bypassing the engine cool-down delay (TDEC), which requires 3 to 5 minutes of unloaded running after utility restoration to prevent engine block and alternator thermal stress.
• Watch out for: Simultaneous motor start-up spikes, which occur when high-draw loads like central air conditioners engage immediately upon switch closure without staggered load management modules.

Audit ATS controller delay settings during scheduled generator maintenance, or call ARS/Rescue Rooter at 866-399-2885 to configure transfer switches and whole-home backup power backed by our Exceptional Service Guarantee.