Uninterrupted Power Supply (UPS) is of three types.
- Offline UPS
- Offline preferred UPS
- Online UPS
| S.No. | Parameters | Offline UPS | Offline Preferred UPS (Line interactive UPS) | Online UPS |
| 1. | Type | Sine wave or Quasi-sine wave | sine wave | sine wave |
| 2. | Voltage | Mains/regulated voltage (±9%) | Regulated voltage (±9%) | Constant rated voltage |
| 3. | Frequency | mains | mains | constant frequency (< ±1%) |
| 4. | Change Overtime | ≅ 10ms | 3-8 ms | No interruption; continuous output |
| 5. | Power factor corrector circuit | No (in general) | Yes | Yes |
| 6. | Power Rating | upto few kVA | upto few kVA | several hundred kVA |
| 7. | Applications | Domestic Use/low power | low & medium power use | sensitive/critical applications |
