As shown in an offline system diagram, during normal operation, utility power flows directly to the load via a bypass route. Only during outages does the battery supply power, which is converted to AC by an inverter.

Features:

1. During normal conditions, power is passed directly to the load with minimal processing; poor noise and surge filtering.

2. Has a switchover time; lowest protection level.

3. Simple design, small size, lightweight, easy to control, low cost.

An online UPS continuously supplies power to the load via the inverter. Only during UPS failures, overloads, or overheating will it switch to bypass mode.

Features:

1. Power to the load is fully processed by the UPS—best power quality.

2. Zero transfer time.

3. Complex design and higher cost.

4. Strongest protection against electrical noise and surges.

Normally, utility power is supplied directly to the load, and the inverter functions as a charger. When a power outage occurs, the inverter converts battery power to AC for the load.

Features:

1. Bi-directional converter design allows faster battery recharge.

2. Has a switchover time.

3. Complex control design, higher cost.

4. Protection level is between online and offline; poor noise and surge filtering.

1. Prioritize equipment stability, reliability, and responsive after-sales service.

2. Look for a well-established local dealer network.

3. Vendor should have strong R&D capabilities.

4. Products should offer high efficiency and low noise.

5. Vendors should be reputable and financially sound.

6. Product certifications like TUV, UL, CSA, etc., are preferred.

7. Manufacturing certifications like ISO9001, ISO14000 are a plus.

Two ways:

1. Add external battery packs: scalable based on required runtime. But note this increases charging time, maintenance, and space requirements.

2. Purchase a higher-capacity UPS: extends runtime and allows for future expansion.