ADE7763ARSZ datasheet(43/56 Pages) AD

43 / 56 page

Data Sheet

ADE7763

Rev. C | Page 43 of 56

Voltage rms compensation is done after the square root.

VRMS = VRMS0 + VRMSOS

(60)

where:

VRMS0 is the rms measurement without offset correction.

VRMS is linear from full-scale to full-scale/20.

To calibrate the offset, two VRMS measurements are required,

for example, at Vnominal and Vnominal/10. Vnominal is set at half of the

full-scale analog input range so that the smallest linear VRMS

reading is at Vnominal/10.

VRMSOS =

VRMS

−

(61)

where VRMS1 and VRMS2 are rms register values without offset

correction for input V1 and V2, respectively.

If the range of the 12-bit, twos complement VRMSOS register is

not enough, use the voltage channel offset register, CH2OS, to

correct the VRMS offset.

Current rms compensation is performed before the square root:

IRMS2 = IRMS02 + 32768 × IRMSOS

(62)

where IRMS0 is the rms measurement without offset correction.

The current rms calculation is linear from full scale to full

scale/100.

To calibrate this offset, two IRMS measurements are required,

for example, at Ib and IMAX/50. IMAX is set at half of the full-scale

analog input range so that the smallest linear IRMS reading is at

IMAX/50.

IRMSOS =

IRMS

−

32768

(63)

where IRMS1 and IRMS2 are rms register values without offset

correction for input I1 and I2, respectively.

Apparent Energy

Apparent energy gain calibration is provided for both meter-to-

meter gain adjustment and for setting the VAh/LSB constant.

VAENERGY =











 +

VAGAIN

VADIV

VAENERGYinitial

(64)

VADIV is similar to the CFDEN for the watt-hour calibration. It

should be the same across all meters and determines the VAh/LSB

constant. VAGAIN is used to calibrate individual meters.

Apparent energy gain calibration should be performed before

rms offset correction to make the most efficient use of the current

test points. Apparent energy gain and watt gain compensation

require testing at Ib, while rms and watt offset correction require

a lower test current. Apparent energy gain calibration can be

done simultaneously with the watt-hour gain calibration

using line cycle accumulation. In this case, LAENERGY and

LVAENERGY, the line cycle accumulation apparent energy

registers, are both read following the line cycle accumulation

interrupt. Figure 78 shows a flowchart for calibrating active and

apparent energy simultaneously.

VAGAIN = INT

























−

)

(

)

(

nominal

expected

LVAENERGY

(65)

LVAENERGYIB(expected) =

INT













)

(

s/h

3600

time

Accumulati

constant

LSB

VAh

nominal

(66)

The accumulation time is determined from Equation 33, and

the line period can be determined from the period register

according to Equation 34. The VAh represented by the

VAENERGY register is

VAh = VAENERGY × VAh/LSB constant

(67)

The VAh/LSB constant can be verified using this equation:

LVAENERGY

time

Accumulati

constant

LSB

VAh

3600

)

(

(68)

ADE7763ARSZ 数据表(PDF) 43 Page - Analog Devices

ADE7763ARSZ 数据表(HTML) 43 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56

数据表下载