Automatic transfer switch manufacturer

Automatic transfer switch is a device to transfer power supply automatically during a power outage. Ranging from households to commercial and industrial premises, ATS has a significant role to play. It not only permits smooth operation of equipment during a power failure, but also reduces manual handling and increases the power system’s dependability and security.

This paper will present an in-depth overview of the operation principle, types, application areas, and choosing proper ATS equipment for automatic transfer switches.

What is an automatic transfer switch

Automatic transfer switch is an electric device whose major role is to automatically transfer to the alternative power source when there is failure in the main power supply. The main purpose of the switch is to avoid shutdown of equipment or safety hazard when there is a loss of power. It is usually used between main power supply, UPS (uninterruptible power supply), and generator sets.

Analysis of the principle of automatic transfer switch

1.Power monitoring and fault detection

ATS continuously monitors the status of the main power supply. If voltage drop, frequency drift, phase loss, or complete power failure is detected, the controller will call the switching program. For example, in the event of a main power failure, ATS uses a 1-second delay (adjustable) to confirm anomalies and avoid false alarms

2.Start-up and preparation for backup power

For a generator backup power source, ATS sends a start command, and the generator transfers when it reaches a stable state (voltage and frequency requirements are achieved). This is done typically with a 3-second delay to prevent improper start-ups of the generator

3.Switching between Execution and Security Assurance

Mechanical interlocking: ensures that two power sources cannot be connected simultaneously through mechanical structure, avoiding the risk of short circuit

Switching method:

• Open transition: After disconnecting the main power supply, briefly cut off the power and then close the backup power supply. Suitable for ordinary loads, the switching time is about 100ms-2 seconds
• Closed transition (such as STS static switch): using electronic devices to achieve “closing first and then closing”, with a switching time of ≤ 8ms, suitable for IT equipment sensitive to power outages
• Intermediate position delay: For high inductive loads (such as electric motors), ATS switches to the intermediate position and stays for 0.5-1 second, waiting for the back electromotive force to decay before completing the switch to avoid current surges

4.Main power restoration and switching back

After the main power supply returns to normal, ATS confirms stability after a preset delay (such as a 30 minute cooling cycle), automatically switches back to the main power supply, and shuts down the backup generator