UPS Technology and Operation

What is a UPS?

UPS is the abbreviation for Uninterruptible Power Supply. In very simply terms a UPS is a power conditioner with a battery. The battery makes it possible to offer protection against power failure / black outs.

Generally there are two types of systems available in the market today – Offline / Standby and Online

A UPS will consist of three key elements:-

  1. Rectifier / Charger– takes the incoming AC supply and converts it to DC to trickle charge the DC battery and where applicable feed the inverter.
  2. Battery– to store the DC energy delivered from the rectifier/charger
  3. Inverter– converts DC from the battery to a regulated AC voltage to feed the critical load.

Standby UPS

Connected equipment will run off the mains supply unless there is a power failure or a sag or a surge. The UPS will then switch internally to use the UPS to generate a single phase 240V to supply the load.


Line Interactive UPS

Equipment normally run off the mains but supply is regulated automatically by boosting or decreasing the voltage supplied to the connected equipment. Will transfer to battery in case of power failure, sags, surges – will also protect against brown outs. Transfer to battery within 10ms. (less than 1/2 a cycle)


True On-Line Double Conversion

Highest level of protection as the load is always connected to the battery to ensure a clean and stable power supply. The UPS will always convert AC input power to DC and then back to AC from the battery.

Completely isolates the load from any mains disturbances and provides highest level of protection



The PowerShield DC Mini is designed to provide emergency power backup to all kinds of DC powered equipment including routers, modems (including fibre optic - ONT), VOIP phone systems, surveillance equipment, alarm systems and many critical telecommunications devices. The DC Mini can economically provide hours of operation during power failure.


Voltage Regulator

Monitors voltage level supplied to a load directly from the mains and will regulatethis to always supply a voltage within an acceptable range. Protects sensitive equipment from brownouts and overvoltages


Surge Filters

Surge Filters contain Metal Oxide Varistors (MOV) to provide protection against overvoltage caused by surges and spikes in the mains power supply. Often also used to supply a single phase UPS as low cost, front line protection in harsh environments.