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Rojony Khatun
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Last updated: October 1, 2025

ATS Automatic Transfer Switch Changeover Wiring Diagram Guide

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Automatic Changeover Switch Connection

Learn ATS automatic transfer switch wiring for seamless power changeover between the main supply and the generator with protection and safe operation.

generator automatic changeover

An ATS (Automatic Transfer Switch) is an automatic transfer of power (between main supply and generator) that is safe. The correct wiring, relays, and protection are the factors that guarantee the smooth functioning of the product not requiring any human interference, to guarantee the consistent flow of power to the essential loads.

main supply to generator wiring

The ATS (Automatic Transfer Switch) is used to provide a smooth transition of power between a mains supply and a backup generator. The wiring diagram exhibits the connections of the line inputs of the utility supply and generator to the ATS, which in turn supplies the load panel automatically. Here, the main items are ATS relay, contactors, control circuits, MCB/ fuses, and correct earthing. In case of failure of the mains, the ATS detects loss of voltage, and the generator is started. When the generator stabilizes at a voltage, the ATS changes the load over to the generator supply. In case of mains return, ATS automatically reconnects the load. Proper wiring will allow the smooth, safe, and reliable operation, back-feed prevention, and protect both the mains and generator systems. ATS is applied to the industrial, commercial, and critical residential connections to ensure the supply of power. The testing will involve checking voltage inlets, relay working, start/stop sequence of the generator, and protective devices to confirm that they work correctly when there is a power failure.

Work & Installation (Input → Output Summary)

  • Mains Supply (L1, L2, L3, N) enters ATS input terminals.
  • Generator Supply (L1, L2, L3, N) enters ATS generator input.
  • ATS Relay & Contactors monitor mains voltage and control load transfer.
  • Load Panel receives supply automatically from mains or generator.
  • Generator Start Signal is triggered by ATS when mains fails.
  • Automatic Return to mains when voltage stabilizes.

Testing & Final Adjustments

  • Verify insulation and proper connection of mains and generator lines.
  • Check ATS relay, contactor operation, and control circuits.
  • Simulate mains failure; ensure ATS signals generator to start.
  • Observe load transfer to generator after voltage stabilization.
  • Restore mains supply and confirm load transfers back automatically.
  • Test protective devices (MCB/fuses) for proper operation.
  • Verify generator stops after return to mains.
  • Check phase sequence and voltage levels on both mains and generator.
  • Ensure proper earthing and labeling for safety.
  • Record test results to confirm reliable ATS operation under various scenarios.

Frequently Asked Questions - Automatic Changeover Switch Connection:

What is an ATS?

An Automatic Transfer Switch that switches load between mains and generator automatically.

Why use an ATS?

To maintain uninterrupted power supply during mains failure.

Which devices are required for ATS wiring?

ATS relay, contactors, control circuits, MCB/fuses, and earthing.

How does ATS work?

It detects mains failure, starts generator, and transfers load automatically.

Can ATS be used for single-phase systems?

Yes, with correct ATS model selection for single-phase supply.

Is overload protection necessary?

Yes, to protect both ATS and load panel from overcurrent.

How to test ATS operation?

Simulate mains failure and verify generator start and load transfer.

Is earthing required?

Yes, for safety of equipment and personnel.

Can ATS prevent back-feeding?

Yes, proper wiring and contactors prevent power back-feed.

Where is ATS commonly used?

Industrial, commercial, and critical residential setups requiring uninterrupted power.

Rojony Khatun

Rojony Khatun

CalculatorToolsProject

Rojony Khatun is the creator of a free online tools website designed to simplify everyday and engineering-related calculations for students, professionals, and hobbyists. The platform offers a wide variety of basic and advanced calculators across key categories, including Electrical Calculators, Electronic Calculators, and Time & Date Calculators, helping users solve problems quickly and accurately.