Coffee Room
Discuss anything here - everything that you wish to discuss with fellow engineers.
12763 Members
Join this group to post and comment.
ISHAN TOPRE • Apr 3, 2012

# Conversion To KWh

How to convert any quantity to KWh if voltage, frequency and Current is given?

Say, my refrigerator has rating 230V, 50Hz, 1.1A. What is the KWh rating?
Also what does VA unit mean?

Does 1 unit of electricity stand for 1Wh?
aarthivg • Apr 3, 2012
Issue
Does 1 unit of electricity stand for 1Wh?
One unit of electricity is exactly equal to 1000 Watts of power used for 1 hour.
aarthivg • Apr 3, 2012
Issue
How to convert any quantity to KWh if voltage, frequency and Current is given?

Say, my refrigerator has rating 230V, 50Hz, 1.1A. What is the KWh rating?
one watt is the rate at which work is done when one ampere of current flows through an electrical potential difference of one volt .
W= V*I
aarthivg • Apr 3, 2012
Issue
Also what does VA unit mean?
Apparent power is expressed as VA unit, product of rms voltage and rms current
VA -voltage-ampere
All calculations are given for single phase AC loads at homes such as refrigerators,heaters,etc:

Issue
How to convert any quantity to KWh if voltage, frequency and Current is given?
Power (KW)= Voltage (V) x Current (A) x Power factor / 1000
Energy (KWh)= Power (KW) x Time (Hrs)

Power factor for AC supply of 50 Hz is normally assumed to be from 0.6 (worst) to 0.8 (still bad!)
Issue
Also what does VA unit mean?
Apparent Power (VA) = Real Power (W) / Power factor

Real power (W) represents the actual energy transfered from source to the load.
As the loads (refrigerators, heaters,etc) are inductive in nature, there is an additional component of power which is not actually transferred to load to do any fruitful work. This component is called reactive power and circulates back and forth between load and source. The net addition of reactive power (VAR) over any full cycle is zero. Eventually, these two components of the power taken from the source add up to apparent power (VAR).

Issue
Does 1 unit of electricity stand for 1Wh?

1 unit = 1 KWh