With this type of UPS, the AC mains is the primary power source where any drop in voltage or battery current is automatically detected by the UPS, which switches over to the backup battery automatically. When AC power is restored, the UPS switches back to pas filtered mains and then recharges the battery.

The inverter is not connected in series with the AC mains, but rather in parallel configuration. There is transfer time associated with this changeover which is typically around four to ten milliseconds, which most computers switch mode power supply unit will not see this break.


Standby UPS often include a filter component, although this is more suited to EMI/RF, and surge protection provided through simple PCB Board mounted ow kA rated MOV components. This surge protection/ filtering is very ineffective at dealing with lightning transients which represent the greatest risk to connected equipment.

Note! Be aware that proper fit for purpose surge protection should be rated min Cat C (6 kV, 20 kA @8/20us), and should include a suitably tuned inductor component which can slow down the rate of voltage and current rise from reaching the connected equipment.

Do not confuse simple MOV and RF Filter as providing a good level of surge protection!!

You want to pay for cheap, you get cheap! Always remember that here is always a good reason why something is cheap, and generally there is a trade off in performance

Powerware 3105 UPS

The affordable, compact 3105 UPS system device was designed to deliver accost effective UPS power management solution for small office or home office applications.

Ready to switch to UPS battery power any time it detects a power problem within the utility, the 3105 UPS provides a short term and reliable power backup power for wireless phones, small office PABX or key phone systems, home office workstations, small office desktop servers, small network nodes, point-of-sale systems, and computer peripheral devices.


Features & Benefits:

  • Protects small office and home office equipment from power outages, surges, sags, and line noise
  • Saves space with a compact design that fits easily under a desk or can be conveniently wall-mounted, with quick access to all power outlet receptacles
  • Keeps essential systems running through short term power outages (four outlets with surge suppression and battery backup)
  • Extend UPS seervice life with user-replaceable batteries
  • Phone line transient protector guards phone equipment from “back door” power surges
  • Stay informed of power problems and low battery conditions with audible alarms and remote alarm notification
  • Deliver short-term mobile power with start-on-battery capability
  • USB port and cable are standard
Product Snapshot
Power Rating 350 – 700VA
Voltage 240 VAC
Frequency 50Hz
Configuration Low profile
Plug-and-Play unit
Topology Standby