**I. Different UPS Types Vary Greatly in Voltage Stabilization Capability**
First, you need to understand that not all UPS units can stabilize voltage. The three common types of UPS on the market handle voltage issues in completely different ways:
1. **Standby UPS: Basically No Voltage Stabilization Capability**
This type is the most affordable and common. When mains power is normal, the current passes directly "through" the UPS to your devices. It offers no filtering or regulation capability for daily occurrences of high voltage, low voltage, or fluctuations. Your equipment directly suffers from all voltage instability. It only solves the problem of "power or no power."
2. **Line-Interactive UPS: The Main Force for Voltage Stabilization**
The biggest difference from the Standby type is its inclusion of a key component: the AVR (Automatic Voltage Regulator).
When the input mains voltage is unstable, the AVR acts like a smart transformer, automatically boosting or bucking the voltage to stabilize the output within a safe range (e.g., 220V). This entire process does not require using the battery, thereby extending battery life. It only switches to battery mode when the voltage anomaly is beyond the AVR's adjustment range or during a complete power outage.
3. **Online UPS: Ultimate Voltage Stabilization**
This type belongs to top-tier protection. It uses "Double Conversion" technology: first, it completely converts the incoming mains power (clean or not) into DC power, then uses an inverter to regenerate an absolutely stable, pure sine wave AC output. Your equipment always receives "clean power" inverted from the battery circuit, completely isolated from dirty mains power.
Simple Summary: Standby (No Stabilization) < Line-Interactive (Excellent Stabilization) < Online (Perfect Stabilization).
### II. Why Are "Line-Interactive UPS" Specially Recommended for Hong Kong Users?
Power issues in Hong Kong are often not about complete outages but about "poor quality": aging wiring in old buildings leads to chronically low voltage, building power equipment switching causes instantaneous sags, and lightning strikes or large machinery startup create surges or interference. A Line-Interactive UPS with AVR is the perfect remedy:
**Handles Daily Fluctuations**: The AVR automatically adjusts, sparing your equipment the stress of long-term operation at abnormal voltages.
**Protects the Battery**: Since the AVR handles most situations, there's no need for frequent switching to battery mode, making the UPS battery last longer.
**High Cost-Effectiveness**: At a reasonable price, it provides the two core protections of **"Voltage Stabilization" + "Backup Power"**, making it the smartest and most practical investment.
**III. Specific Model Recommendations for Voltage Stabilization Needs**
1. APC Back-UPS Pro / BR Series (Line-Interactive)
**Recommendation Reason**: A classic brand under Schneider Electric, widely recognized for reliability. The entire series is equipped with AVR, offers a complete model range (from 600VA to 1500VA+), and has excellent software support (PowerChute software), allowing easy setup for automatic shutdown linkage with NAS systems like Synology and QNAP.
**Target Users**: General users who pursue well-known brands, stable reliability, and need comprehensive voltage protection for computers, NAS, and network equipment.
2. **Eaton 5P / 5S Series (Line-Interactive)**
**Recommendation Reason**: From a top-tier industrial brand in the power management field, renowned for exceptional durability and stability. Its AVR circuit design is robust, capable of withstanding a wider and harsher input voltage range, with excellent filtering effects and very quiet operation.
**Target Users**: Users with strict quality requirements, protecting high-end workstations or valuable equipment, and willing to invest in long-term durability.