UPS Type or Inverter?

UPS definition:
Uninterruptible Power Supply

UPS Ensures equipment will continue functioning without interruption – as if nothing had occurred!

UPS is your power back-up and is generally used to ensure that there is absolutely no interruption of power to your equipment.
Although there may be a power failure, power surges, power sags or spikes your UPS will ensure a constant flow of power to operate the equipment.
With the correct power back up your equipment will continue functioning without interruption – as if nothing had occurred.


  • A UPS consists of an Inverter, Transformer, Voltage regulator, Charger and Batteries. 
  • UPS sizes range from 500VA to 240 KVA. 
  • Transformer based UPS are more robust serving as power backups on heavier equipment and machinery.

Transformer based UPS have proved more reliable under severe conditions such as where power outages are extended for longer periods of time. Such as where power cuts are a more regular occurrence and in areas where more power spikes or surges are experienced. 

The Inverter

  • An inverter is the subassembly of a UPS that converts DC power to AC power electronically.
  • The inverter is the device that changes DC (12v, 24v or 32v etc.) from a battery to 220VAC. 
  • It regulates the output constantly even while the battery is discharging – ensuring a stable 220VAC supply – smoothing out any small irregularities that may cause voltage fluctuations.

When calculating the battery size for your requirements the inverter allowance is included in the calculation. These units draw very little power from the battery and are generally quite reliable if not overloaded.

This smaller type of UPS is used for general office and home equipment. The smaller UPS does not need to convert large quantities of power for extended periods of time.
Therefore a different technology is used in the design.
This high-frequency UPS converter-unit is designed to be more cost-effective and excludes the use of a large expensive transformer to convert power.

A High-Frequency conversion and ‘line-interactive’ technology is used for power backups, and are often referred to as ‘INVERTERS’ (which still includes the inverter, charging circuit and battery) rather than a UPS. 
Running an Inverter-UPS is a very cost-effective means to standby power. are used in general office and household equipment that draw less current and normally run for a shorter period of time.
Reducing the costs of a UPS with satisfying results. For specific usages see UPS Power SOLUTIONS

Home & SME Power solutions

Types of UPS

Various operating methods have been employed for contrasting requirements. This allows the UPS to be engineered according to individual needs – Depending on the quality of power and period of back up time required determines what type of UPS should be used. 

There are three basic circuits used each with its own advantages.
A) – On-Line,
B) – Off-Line and
C) – Line Interactive.

A) – On-Line UPS

On-Line UPS

The On-Line UPS is a continuous pure Sine Wave power supply which is the same as provided by mains. This double-conversion UPS, operating under normal conditions, supplies clean smooth AC power after rectification.
Only when the UPS is overheating, overloaded, or out of order will the unit switch to bypass mode.

Having a smooth change over this UPS is ideal for:

  • Intermediate connection for Generator back up.
  • Equipment using motors (Such as printers)

B) – The Off-Line UPS will only supply power when there is a power failure

Off-Line UPS

The Off-Line UPS
Change over has very little effect on the following equipment.

  • Fans
  • Lamps
  • Small Fridges
  • TV, Video player, Radio etc…

C) – Line Interactive UPS

Line Interactive UPS

The Line Interactive UPS supplies power from the bypass through its own transformer and the transformer is part of the charging circuit.
When there is a power failure the transformer will transfer battery power to AC output.
A milli-second break-in change over is normally insignificant to effect most processor driven equipment.
Such as: Computers and Servers

Need to know – UPS Batteries

A ‘Deep Cycle’ battery is always recommended for UPS back up – Allows for large quantities of current to be drawn for long periods of time
ie. Will deliver a continuous flow of current until flat without damaging internal plates.

The battery size is measured in Ah (Ampere Hours),
This will depend on:
a) How much power is needed to operate the equipment effectively and 
b) How much backup time is required for the equipment to
continue operating?

Things of note when purchasing your UPS

  1. Consider your requirements of power quality
  2. Review the UPS specifications for high efficiency and low noise
  3. Calculate the current capacity needed and consider future expansion
  4. Reputed brands and manufactures for reliability
  5. Choose the UPS based on your requirements