SA9604A

sames

14/20

Example:

V = 230V

I = 80A

Active Power

= 230V x 80A x (n/t)/640000

Reactive Power = 230V x 80A (n/t)/(640000 x 2)/Pi)

n

=

Difference in register values between successive reads (delta

value)

t

=

Time difference between successive reads (in seconds)

To calculate the measured voltage, the following formula is applied:

V

measured

=

V * n

940 000 * t

Where

V =

Rated Voltage

t

=

Time difference between successive reads

n =

Difference in register values between

successive reads

The Voltage calculated is the average voltage. The voltage measurement will give

an accuracy of better than 1% for a voltage range of 50% to 115% of the rated mains

voltage if the voltage is a pure sine wave.

The mains frequency may be calculated as follows:

Frequency

=

Crystal frequency

Register Value * 2

7.

Calibration

For accurate results we would recommend the following software calibration

procedure:

7.1 Active energy

Establish a calibration factor for active energy (Ka) at pf close to 1.

Active Measured = Active_Register_Value x Ka