ADE7758_15 datasheet(47/72 Pages) AD

47 / 72 page

Data Sheet

ADE7758

Rev. E | Page 47 of 72

START

STEP 1

ENABLE CF

OUTPUTS

STEP 2

CLEAR OFFSET

REGISTERS

xWATTOS, xVAROS

ALL PHASES

WATT OFFSET

CALIBRATED?

YES

ALL PHASES

VAR OFFSET

CALIBRATED?

YES

SET UP APCF

PULSE OUTPUT

FOR PHASE A, B,

OR C

STEP 4

STEP 3

SET UP SYSTEM

FOR IMIN,VNOM,

PF = 1

STEP 5

MEASURE %

ERROR FOR

APCF

STEP 6

CALCULATE AND

WRITE TO

xWATTOS

END

SET UP VARCF

PULSE OUTPUT

FOR PHASE A, B,

OR C

STEP 4

STEP 3

SET UP SYSTEM

FOR IMIN,VNOM,

PF = 0, INDUCTIVE

STEP 5

MEASURE %

ERROR FOR VARCF

MEASURE PERIOD

USING FREQ[11:0]

STEP 6

CALCULATE AND

WRITE TO

xVAROS

STEP 7.

REPEAT STEP

3TO STEP 6

FOR xVAROS

SELECT PHASE

FOR LINE PERIOD

MEASUREMENT

CONFIGURE

FREQ[11:0] FOR A

LINE PERIOD

MEASUREMENT

Figure 80. 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: Clear the xWATTOS and xVAROS registers.

Step3: Disable the Phase B and Phase C contribution to the APCF

and VARCF pulses. This is done by the TERMSEL[2:4] bits of

the COMPMODE register (0x16). Setting Bit 2 to Logic 1 and

Bit 3 and Bit 4 to Logic 0 allows only Phase A to be included in

the pulse outputs. Select Phase A, Phase B, or Phase C for a line

period measurement with the FREQSEL[1:0] bits in the MMODE

Phase A for line period measurement.

Step 4: Set the test system for IMIN, VNOM, and unity power factor.

For Step 6, set the test system for IMIN, VNOM, and zero-power

factor inductive.

Step 5: Measure the percent error in the pulse output, APCF or

VARCF, from the reference meter using Equation 49.

Step 6: Calculate xWATTOS using Equation 56 (for xVAROS

use Equation 57).

APCFNUM

APCFDEN

APCF

%APCF

xWATTOS

EXPECTED

ERROR

⎟

⎠

⎞

⎜

⎝

⎛

100

–

(56)

ADE7758 Datasheet(PDF) 47 Page - Analog Devices

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