ADE7758ARWRL datasheet(46/68 Pages) AD

46 / 68 page

ADE7758

Rev. A | Page 46 of 68

START

STEP 1

ENABLE CF

OUTPUT

STEP 2

SET OFFSET

REGISTERS

XWATTOS, XVAROS

TO LOGIC 0

ALL PHASES

WATT

OFFSET AND

VA OFFSET

CALIBRATED?

YES

ALL PHASES

VAR OFFSET

CALIBRATED?

YES

SET UP APCF

PULSE OUTPUT

FOR PHASE A, B,

OR C

STEP 3

SET UP SYSTEM

FOR IMIN, VNOM,

PF = 1

STEP 4

MEASURE %

ERROR FOR

APCF

STEP 5

CALCULATE AND

WRITE TO

XWATTOS

END

SET UP VARCF

PULSE OUTPUT

FOR PHASE A, B,

OR C

STEP 3

SET UP SYSTEM

FOR IMIN, VNOM,

PF = 0

STEP 4

MEASURE %

ERROR FOR VARCF

MEASURE PERIOD

USING PERIOD

STEP 5

CALCULATE AND

WRITE TO

XVAROS

STEP 6.

REPEAT STEP

3 TO STEP 5

FOR XVAROS

Figure 79. Offset Calibration Using Pulse Output

Step 1: Repeat Step 1 and Step 3 from the gain calibration to

configure the ADE7758 pulse output.

Step 2: Set the xWATTOS and xVAROS registers to Logic 0.

Step 3: Set the test system for ITEST = IMIN, VNOM, and unity power

factor. For Step 6, set the test system for ITEST = IMIN, VNOM, and

zero-power factor.

Step 4: Measure the percent error in the pulse output, APCF or

VARCF, from the reference meter using Equation 31.

Step 5: Calculate xWATTOS using Equation 38 (for xVAROS

use Equation 39).

xWATTOS

()

APCFNUM

APCFDEN

APCF

EXPECTED

ERROR

–

(38)

xVAROS

(

)

VARCFNUM

VARCFDEN

VARCF

EXPECTED

ERROR

–

(39)

where Q is defined in Equation 40 and Equation 41.

For xWATTOS

25 ×

CLKIN

(40)

For xVAROS

202

⎟

⎠

⎞

⎜

⎝

⎛

PERIOD

CLKIN

(41)

where PERIOD is measured from the FREQ (0x10) register.

Step 6: Repeat Step 3 to Step 5 for xVAROS calibration.

ADE7758ARWRL Datasheet(PDF) 46 Page - Analog Devices

ADE7758ARWRL Datasheet(HTML) 46 Page - Analog Devices

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