When using the automatic calibration, the calculations are done by the Demo Meter
application firmware, so the Excel sheet is not needed. The automatic calibration is
done by means of the CNF and the CAL commands:
The CNF command is used to
configure the metrology library according to the input network hardware as well
as the programmable gain of the internal amplifiers. Refer to the Demo Meter Application Command Console for additional
information.
The CAL commands include
parameters to provide the input conditions (voltages, currents and angles being
applied by the Meter Tester) to the application firmware. When received, the
Demo Meter application firmware computes the calibration parameters. There are
two variants of the CAL command: the first one calibrates one phase
individually; the second one is valid for a poly-phase system and calibrates all
the phases at the same time. Refer to the Demo Meter Application Command Console for additional
information.
The CNF command for an evaluation board with the following configuration:Figure 1-58. Board HW Configuration
Would be the
following:
>CNF(MC=3200,ST=0,F=50.00,G=1,Tr=2000,Rl=3.24,Ku=1651)
Configure Meter is Ok !
>
The next steps describe the calibration procedure:
Send a CNF command. If the
programmable gain of the internal amplifiers changes, then:
Send an RST command to
apply the new gain.
Send the CNF command
again.
Apply the input conditions
(voltages, current and angles), then wait until the input stabilizes.
Send a CAL command.
Warning: The CNF command affects all channels, so it is not valid for meters with different
kinds of sensors, for example, a combination of Rogowski coils and CTs or CTs with
different current transformer ratio or different burden resistors.
