sames

sames

SA2005P

11/16

http://www.sames.co.za

Recalculate the rated conditions

Krx = 642 000 / Rated volt / Rated current / 6400 x 3600 x

1000 / 512 x (1 + %MinError / 100 )

Krx = 642 000 / 230 / 80 / 6400 x 3600 x 1000 / 512 x 1.015

Krx = 38.9077

Kr = 38 - 1 = 37

The 37 are stored in the rated register.

The channel balance values are adjusted to make provision for

the rounding error.

Gain = ((Krx - Kr +1 ) / Krx ) x 100

Gain = (( 38.9077 - 38 ) / 38.9077 ) x 100

Gain = 2.33

The channel balance pre-devider value must be recalculated.

(BMIN will be the lowest %error value, in this case 1.5%,

CHB1, CHB2 and CHB3 are the individual phase %errors

measured.

Cb1 = (CHB1 - CBMIN + Gain ) x 256 / 100

Cb1 = (1.5 - 1.5 + 2.33 ) x 256 / 100 = 5.97 =5

Cb2 = (CHB2 - CBMIN + Gain ) x 256 / 100

Cb2 = ( 5.2 - 1.5 + 2.33 ) x 256 / 100 = 15.43 = 15

Cb3 = (CHB3 - CBMIN + Gain ) x 256 / 100

Cb3 = (3.2 - 1.5 + 2.33 ) x 256 / 100 = 10.316 = 10

Store the calculated values in the EEPROM and the meter is

calibrated.