How to Work automatic transfer switch(ATS) with dual power supply

 

1) what is the ATS ?

ATS is abbreviation of automatic transfer switch, it is use to change over power source of dual feedings i.e Primary source & secondary source.

2) How many incoming source in ATS switch.

ATS connected from two source i.e.
👍primary_source generally electricity supply from government/private organization and  secondary_source will be generator and interrupted power supply(UPS) etc.

 

 

3) How to Work Automatic Transfer Switch (ATS) with Dual Power Supply

 

3.1 Introduction

An Automatic Transfer Switch (ATS) is an important electrical switching device used to ensure uninterrupted power supply to critical loads. It automatically transfers the electrical load from the main power source to an alternate power source whenever the main supply fails. ATS systems are widely used in industries, hospitals, data centers, railway installations, commercial buildings, and residential complexes.

In a dual power supply system, the ATS continuously monitors two independent power sources, commonly known as the Primary Source and the Secondary Source. When the primary source becomes unavailable or its voltage goes beyond the acceptable range, the ATS automatically switches the load to the secondary source without requiring manual intervention.

 

3.2 What is a Dual Power Supply ATS?

A Dual Power Supply ATS is designed to work with two incoming power sources. These sources may be:

• Utility Supply and Generator
• Solar supply and local Grid supply 
• Utility Supply and Utility Supply
• Grid Supply and Solar Inverter
• Main Feeder and Backup Feeder

The ATS ensures that the load receives power from only one source at a time, preventing dangerous back-feeding and electrical faults.

 

3.3 Main Components of an ATS

1. Power Contactors or Circuit Breakers

These are used to connect and disconnect the load from the available power source.

2. Voltage Monitoring Relay

It continuously monitors voltage, frequency, and phase conditions of both power supplies.

3. Control Unit

The control logic determines when to transfer the load and when to restore it to the preferred source.

4. Mechanical and Electrical Interlocking

Interlocking prevents both power sources from being connected simultaneously.

5. Timer Circuits

Timers prevent nuisance switching due to short-duration voltage fluctuations in mili or microsecond time.

 

3.4 Working Principle of ATS with Dual Power Supply

 

3.4.1 Normal Operation

Under normal conditions when power supply is ON:

• Source 1 (Main Supply) is healthy.
• ATS keeps the Source 1 contactor closed.
• Source 2 contactor remains open.
• The load receives power from Source 1.

 

3.4.2 Power Failure of Main Supply

When Source 1 fails due to:

• Power outage
• Low voltage
• High voltage
• Phase failure
• Frequency abnormalities

The ATS detects the fault and starts a preset transfer timer.

After confirmation of the fault:

• Source 1 contactor opens.
• ATS verifies complete disconnection.
• Source 2 contactor closes.
• Load is transferred to Source 2.

The entire process usually takes a few seconds depending on ATS settings.

 

3.4.3 Restoration of Main Supply (Reverse as Normal mode) 

 

When Source 1 becomes healthy again or grid supply restrored:

• ATS monitors the source for a preset stabilization period.
• Source 2 contactor opens.
• Source 1 contactor closes.
• Load returns to the preferred power source.

This operation is called Automatic Re-transfer.

 

4. Advantages of Dual Power Supply ATS

 

4.1 Continuous Power Availability

The load remains energized even when one source fails.

4.2 Improved Reliability

Critical equipment receives uninterrupted power.

4.3 Reduced Manual Intervention

No operator is required for switching.

4.4 Enhanced Safety

Interlocking prevents simultaneous connection of both sources.

4.5 Faster Restoration

Power transfer occurs automatically within seconds.

 

5. Applications of Automatic transfer Switch (ATS)

Dual power supply ATS systems are commonly used in:

•  society and office Area
• Railway signaling systems
• Data centers
• Hospitals
• R.O Plants 
• Telecom towers
• Industrial plants
• Commercial buildings
• Water treatment plants
• Emergency lighting systems

6) Function of ATS.

An automatic transfer switch (ATS) is a device that automatically transfers a power supply from its primary source to a backup source when it senses a failure or outage in the primary source. When a failure occurs in a primary power system, the ATS invokes a standby power source, such as an uninterrupted power supply. An ATS can also start up more long-term backup power systems, such as local diesel generators, to run electric equipment until utility power is restored.

Since the ATS is connected to both primary and backup power sources, it serves as an intermediary between equipment and the power supplies, acting as an electrical relay. An ATS can also act as a redundant, rack-mounted power supply for equipment that is connected to a power source with only one cord.

In the data center, it is vitally important to have uninterrupted power. To achieve this goal, the systems in the power path must be properly maintained and tested. To ensure reliability in the event of a power outage, data center administrators need to routinely monitor the ATS.
 ATS units can channel considerable amounts of energy, which can put heavy stress on the electrical contacts involved, so regular maintenance is critical.

6. How to remotely control an automatic transfer switch.

As you see on the automatic transfer switch Video, you can connect a switch for a remote control from BMS (building management system).
In side ACB under voltage coil also function to open Load supply if incoming voltage down to under 200 volt for domestic use and 370 volt for 3 phase power system.

 

 

7. Important Safety Considerations beforeput in ATS operation 

• Ensure proper electrical interlocking between sources.
• Verify correct phase sequence before commissioning.
• Periodically test ATS operation.
• Inspect contactors and control wiring regularly.
• Follow local electrical safety standards and regulations.

 

8. Conclusion

An Automatic Transfer Switch (ATS) with dual power supply is a reliable solution for maintaining uninterrupted electrical power. By continuously monitoring both power sources and automatically transferring the load during supply failures, ATS systems improve operational reliability, safety, and efficiency. Proper installation, testing, and maintenance ensure long-term dependable performance in critical electrical applications.

 

Keywords: Automatic Transfer Switch, ATS Working Principle, Dual Power Supply ATS, Automatic Changeover System, ATS Control Logic, Power Transfer Switch, Electrical Distribution System, Industrial ATS Panel.