PRELIMINARY TECHNICAL DATA

EVAL-ADE7756EB

–7–

REV. PrB 01/01

PRELIMINARYTECHNICALDATA

Calibrating the meter

In order to calibrate the energy meter, the line voltage,

test current, line frequency and meter constant are entered

as shown in Figure 8. In this example the line voltage is

entered as 220V, test current is 5A, frequency is 50Hz and

the required meter constant is 3200imp/kWh. With the

parameters entered and the voltage and current circuits

energized, click the calibrate button. The software will

then execute the calibration routine and automatically start

to register energy.

If a HP/AGILENT53131A frequency counter is connected

to a GPIB card of the desktop computer, the software will

automatically read the value of the CF frequency and

process the calibration routine. In this case, the calibration

takes about 5 seconds and the user will be notified when it

is complete.

Otherwise, calibration can be proceeded by changing

CFDIV and APGAIN registers as explained in the

ADE7756 datasheet. The measured CF output frequency

is then adjusted to match the theoretical CF freq. of the

Eval software.

Ensure that the analog input signal levels have been

matched to the transducer output signal levels as described

previously.

Main Selection

In order to access all the internal registers of the

ADE7756 the user must return to the Main Selection

Menu. Figure 9 shows the Main Selection Menu and the

various options. From here such things as phase compen-

sation and Channel 1 and Channel 2 PGA setting can be

made.

Figure 9—Selection Menu & PGA Settings

To select another option from the menu simply click

on the selection menu. By using the selection menu

the user can read and write the registers of the

ADE7756. This software should be used in conjunc-

tion with the ADE7756 data sheet.

Waveform Sampling Routine

In this mode, the Evaluation Software programs the

ADE7756 for Waveform sampling with an updated

rate of 3.5ksps (CLKIN/1024). The user can define

the number of samples needed and select the Signal

Waveform to transfer. Three parameters are processed

when the waveform is displayed: RMS value, Mean

value and Standard Deviation.

When using this feature with sinewave signals, the

user should be aware that if the samples represent a

non entire number of period of the selected signal

then the RMS and Mean values are biased. To correct

this, the number of samples should be chosen to give

an entire number of signal cycles:

Frequency

Signal

Frequency

CLKIN

ADE

cycles

signal

samples

×

×

=

1024

7756

#

#

Note: If Channel 1 and Channel 2 are at the same

frequency then the signal frequency of the Multiplier

Waveform shoud be chosen as twice the Channel1

Frequency to correct the Signal Processing bias.

On line help

The ADE7756 evaluation software also comes with

on-line help features. In order to activate the help

function goto Help on the Menu Bar and select "Show

Help"—see Figure 10. A Help Window will open. In

order to get a description of a particular option (e.g.,

button, text box etc.) move the cursor over the item of

interest. The Help window will display a description

of the selected item.

Figure 10—On-line Help Function.