1. What is ATS?
ATS (Automatic Transfer Switch) is the most widely used dual-power switching device in power systems. Its core characteristics are mechanical structure and relatively long switching time.
It is mainly used to automatically switch between the main power supply (mains electricity) and backup power supply (diesel generator). The switching time is typically between several seconds and tens of seconds.
When one power supply fails or cuts out, the ATS can automatically switch the load from one power source to another to ensure a continuous power supply.
2. What is STS?
STS (Static Transfer Switch) is a high-speed, non-mechanical electronic switch used for uninterrupted switching between two independent AC power supplies.
Its core mission is: when the main power supply malfunctions, switch the load to the backup power supply within milliseconds, ensuring that load devices barely perceive a power outage. It is often used with energy storage systems.
3. Comparison of Key Differences
| Comparison Item | ATS (Automatic Transfer Switch) | STS (Static Transfer Switch) |
|---|
| Operating Principle | Mechanical structure, with contacts driven by a motor or electromagnet | Electronic structure, based on power electronic devices such as silicon-controlled rectifiers (SCRs) |
| Switching Time | Second-level | Millisecond-level (usually ≤50ms, some within 8ms) |
| Power Interruption | A brief power outage occurs during switching | Achieves uninterrupted switching; load is almost unaffected |
| Power Supply Requirements | No strict requirement for synchronization between two power supplies | Generally requires two power supplies to be basically synchronized (same frequency, same phase), otherwise switching may fail or cause impulse damage |
| Core Components | Relays, contactors, molded case circuit breakers, motor drive mechanisms | High-speed SCRs, intelligent control boards, circuit breakers |
| Typical Applications | Building fire protection systems, hospital backup power, general lighting & power distribution in shopping malls & office buildings, main/backup power switching for industrial production lines | Data centers, telecommunication rooms, financial trading systems, precision industrial control, power automation systems |