Industry changes:
• Older UPS models: PF=0.7~0.8
• New high-end UPS: PF=1.0 (e.g., 1kVA can support a 1kW load)
A UPS with a low power factor may appear to have a large capacity, but it can actually only power a few devices.
Rated output voltage
UPS output voltages generally come in two types:
• 220V/230V: Applicable to Chinese, European, and other standards
• 110V/120V: Compatible with US, Japanese, and other standards
Some high-end models support adjustable output, which can adapt to different national voltage standards.
Choosing the wrong voltage can cause equipment to malfunction or even burn out completely.
Rated frequency
• Commonly used frequencies are 50Hz (China, Europe) and 60Hz (USA, Japan).
• Some UPS systems support 50/60Hz adaptive switching.
• Frequency stability is crucial for servers and communication equipment, as frequency drift can lead to clock errors or even system crashes.
The duration of continuous power supply from the start of a power outage until the battery is depleted by the UPS.
Influencing factors:
• Load size
• Battery capacity
• UPS Type (Standby/Online)
Selection Recommendations:
• Office computers: 5-10 minutes is sufficient to save files and shut down.
• Server room: 15-30 minutes, allowing time for switching to generator.
• Core system: >30 minutes or even several hours (external battery pack required)
Conversion time
The time required for the UPS to switch to battery power after a mains power outage.
Type comparison:
• Line-interactive: 2~10 milliseconds
• Online Double Conversion: Almost 0 milliseconds (0~4ms)
For sensitive equipment (such as financial trading systems), even a 5ms delay can cause a system to go offline, so online UPS systems are commonly used.
Common types:
• VRLA (Resistant-Free Lead-Acid) Batteries: Low cost, easy to maintain
• Lithium-ion batteries: long lifespan, small size, high price
Nickel-cadmium batteries: heat resistant and long lifespan, but pose significant environmental problems.
Capacity calculation:
Capacity (Ah) × Voltage (V) = Battery Energy (Wh)