What Is A Dual Power Automatic Transfer Switch?

Automatic switchgear is an electrical device designed to automatically switch load to backup power in the event of a power failure to ensure continuous power supply of critical load. Widely used in hospitals, data centers, airports, banks and other locations with high demand for electricity, it can also be used in the construction of fire protection power distribution system.
Core Functions
Automatic switching switch: real-time monitoring of voltage, frequency and other parameters of primary and backup power sources. In the event of a major power anomaly (e.g., voltage deficit, voltage loss or phase loss), the switch automatically disconnects the main power supply and connects to the backup power supply. Once the main power supply is restored, the switch will automatically or manually switch back to the main power supply.
Protection Functions: Some models,such as CB Class, have overflow release devices that quickly disconnect circuits to provide additional protection in the event of a short circuit.
Logic control: A microprocessor or logical control board decides whether to trigger a switch based on predetermined parameters,such as voltage thresholds and delay times, to prevent false tripping.
Operational principles
Parameter Monitoring: The parameters of two kinds of power supply are compared in real time by using Voltage sensors and frequency detection module. Logical hypothesis: Switch logic is triggered when main power parameters exceed the set threshold (e.g., when the undervoltage exceeds 85% of rated value, or when the voltage loss lasts more than 0.5 seconds).
Action Execution: The interlocking switching of two power sources is achieved by means of an electromechanical linkage mechanism ( (contactor/circuit breaker) or a static electronic switch (thyristor) to ensure that the two power sources are not connected simultaneously.
Return mechanism: Most ATSEs are pre-programmed primary power sources. After the main power supply returns to a stable state (say, 20 seconds), perform a a reverse switchover.
Main Categories
PC-Class ATSE:
Structure: overall structure, using load switches or disconnections as actuators.
Features: Can connect and carry normal current, but lacks the ability to interrupt short-circuit current, can only withstand short-circuit current without damage.
Uses: For applications requiring high power continuity without additional short-circuit protection, such as small commercial buildings and residential areas.
Advantages: Low cost, simple and reliable structure, suitable for low load and infrequent operation. CB-Class ATSE:
Structure: circuit breaker type.
Features: Not only can it be switched between two power sources, but it can also be quickly disconnected in the event of a short circuit, providing higher security.
Uses: Widely used in hospitals, data centers, airports, etc., where high reliability power supply is needed, especially for high power motor or high sensitivity load environment.
Strengths: It provides enhanced safety protection mechanisms and supports higher current specifications to meet diverse needs.
Key Technical Parameters
Rated Voltage: 100V AC or 1500V DC.
Rated current: Rated current varies from a few amperes to several a few thousand amperes depending on the load (generally recommended to be at least 125% of the load).
Transmission time: the time from one power source to another. An optimal design minimizes this time to minimize impact on sensitive loads (e.g. standard switching ≤ 8ms 8ms for STS static transmission switches).
Protection rating: usually IP20 (clean, dry indoor environment) to IP67 (outdoor, wet or dusty environment). Application Scenarios
Medical facilities: Operating theatres, intensive care units and other an uninterruptible power supply dependent facilities ensure the continued operation of medical equipment.
Data Center: Combine with UPS to implement millisecond power switch to prevent business interruptions.
Commercial buildings: Provide power redundancy for lighting, elevators, fire alarm systems and other equipment to reduce the risk of prolonged power outages.
Industrial production: Maintenance of production lines in chemical and metallurgical industries to prevent economic losses or safety incidents due to power outages.
Selection Recommendations
Determine operating conditions: confirm rated voltage, frequency, phase number (single phase/three phase) and rated current to ensure compatibility.
Determine transfer logic: Select and prioritize automatic transmission with automatic recovery (automatic transmission after main power is restored) or automatic transmission without automatic recovery (manual transmission required).
Consider add-ons: select over-and under-voltage detection, frequency detection, and communication interfaces (such as RS485/Modbus) depending on your needs.
Physical Environmental Assessment: Validation of installation space and protection levels (e.g. IP20 to IP67) to comply with site requirements. Reference to industry standards: meet specifications such as GB/T14048.11 and IEC 60947-6-1 to ensure product performance and safety.