What is a UPS?


A UPS is not solely designed to overcome power cuts. Its role is also to stabilise the voltage and eradicate interference.

The UPS is an important link in the security of IT systems. Its main job is to takeover from the mains power supply when power cuts occur, giving users time to save the work in progress.

Power cuts are not the only incidents that these appliances are confronted with. Filtering, as well as regulating the voltage, also form part of the key functions to be provided.

A good UPS should not only ensure an uninterrupted power supply to the connected appliances but also a high quality power supply.

A UPS is made up of three parts:

  • The rectifier which converts AC to DC power designed to charge the batteries and supply the UPS.
  • The batteries which store the energy.
  • The UPS which converts the DC power supplied by the rectifier or batteries to 230 V AC power at 50 Hz, identical to the mains.

The UPS also comes with an automatic closedown software: in the event of a mains power failure this software (installed on the computer connected to the UPS) will automatically close down all programmes after having carried out any necessary backups.

How to choose the right UPS

Step 1:
Know how to calculate the power your setup requires:

  1. Take note of the consumption in Amperes, Watts or VA for each appliance to be protected.
  2. Calculate the sum of the recorded values (in the same unit of measurement).
  3. Choose a UPS with a higher power than the sum of the connected load.
 

Note:

  • If the values are expressed in Amperes, multiply by 230 to obtain the value in VA
  • Example  : 7.5 A x 230 V = 1,725 VA
  • If the values are expressed in Watts,
    multiply by 0.7 to obtain the value in VA.

The formulae:
Apparent power = Voltage x Strength
VA = V x A
Effective power = apparent power/cos (power factor)
W = VA / [cos (power factor)]

Note: in general, it is considered that the cos (power factor) has a value of 0.70

It is important to ensure that the supplied load
does not exceed the UPS capacity.
Step 2:
Choose the technology that suits your setup.
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