With so many gadgets invading our living room, one of the most basic technical calculation has to be known by all.
Gadgets like stabilisers, gensets, UPS, inverters, etc come in KVA ratings. KVA stands for Kilo Volt Ampere.
Appliances on the other hand come with power ratings give in watts or wattage. That is the amount of power the equipment will consume. KW stands for kilo watts.
Conversion of KVA to KW
The mathematical formula for conversion is –
KVA x PF = KW
Where PF stands for Power Factor which is usually taken as 0.8
Power Factor is relation between theoretical power that can be provided and the actual power that is consumed by the equipment. If the equipment is poorly designed the PF will rise.
Definition of Volt, Ampere and Watt
Volt or voltage is the potential difference between two points or terminals.
Ampere or Amps is the current flowing through any circuit.
Watt or wattage is the product of amps and volt and is the total energy.
Example of where the calculation can be used
Let us take the example of calculating the requirement of UPS for a computer. A standard desktop home computer will consume 300 watts of power at peak load. That is the rating written on the power supply unit of SMPS where the main power cable is connected. You also have accessories like speakers and monitor. Finally adding the printer which will consume 50 watts. So to be on the safer side we can total the power requirement to 420 watts.
As per the formula the requirement of a UPS will be of 0.525 KVA or 525 VA. So a 600VA UPS can suffice in this case. The ideal UPS for this would be APC Back-up BX 600C.