Offline UPS (VFD – Voltage/Frequency Dependent)
During normal operation, an offline UPS will supply raw mains to the critical load via its bypass line and static switch. In the event of a power failure, the static switch will transfer the load to the UPS inverter and batteries. In a offline UPS, this transfer time will typically last between 4ms and 10ms. In industries such as IT and Telecoms, this changeover time is deemed unsuitable for the high sensitivity of modern equipment.
Advantages
- Low initial purchase cost
- Small form factor
- Lower running costs
Disadvantages
- Lengthy changeover time
- Limited autonomy
- Limited communication options
- Leaves load equipment subject to varying supply voltages
- Only available up to 2kVA
- Protects against the least of the 9 major power anomalies