71M6534H Demo Board User’s Manual
Page: 49 of 86
© 2005-2007 TERIDIAN Semiconductor Corporation
V2-0
2.2.5 CALIBRATION SPREADSHEETS
Calibration spreadsheets are available from TERIDIAN Semiconductor. They are also included in the CD-ROM
shipped with any Demo Kit. Figure 2-3 shows the spreadsheet for three measurements. Figure 2-4 shows the
spreadsheet for five measurements with three phases.
For CT and shunt calibration, data should be entered into the calibration spreadsheets as follows:
1. Calibration is performed one phase at a time.
2. Results from measurements are generally entered in the yellow fields. Intermediate results and
calibration factors will show in the green fields.
3. The line frequency used (50 or 60Hz is entered in the yellow field labeled AC frequency.
4. After the voltage measurement, measured (observed) and expected (actually applied) voltages are
entered in the yellow fields labeled “Expected Voltage” and “Measured Voltage”. The error for the
voltage measurement will then show in the green field above the two voltage entries.
5. The relative error from the energy measurements at 0° and 60° are entered in the yellow fields labeled
“Energy reading at 0°” and “Energy reading at 60°”. The corresponding error, expressed as a fraction
will then show in the two green fields to the right of the energy reading fields.
6. The spreadsheet will calculate the calibration factors CAL_IA, CAL_VA, and PHADJ_A from the
information entered so far and display them in the green fields in the column underneath the label
“new”.
7. If the calibration was performed on a meter with non-default calibration factors, these factors can be
entered in the yellow fields in the column underneath the label “old”.
For a meter with default calibration factors, the entries in the column underneath “old” should be at the
default value (16384).
A spreadsheet is also available for Rogowski coil calibration (see Figure 2-5). Data entry is as follows:
1. All nominal values are entered in the fields of step one.
2. The applied voltage is entered in the yellow field labeled “Input Voltage Applied” of step 2. The entered
value will automatically show in the green fields of the two other channels.
3. After measuring the voltages displayed by the meter, these are entered in the yellow fields labeled
“Measured Voltage”. The spreadsheet will show the calculated calibration factors for voltage in the
green fields labeled “CAL_Vx”.
4. The default values (-3973) for PHADJ_x are entered in the yellow fields of step 3. If the calibration
factors for the current are not at default, their values are entered in the fields labeled “Old CAL_Ix”.
5. The errors of the energy measurements at 0°, 60°, -60°, and 180° are entered in the yellow fields
labeled “% Error …”. The spreadsheet will then display phase error, the current calibration factor and
the PHADJ_x factor in the green fields, one for each phase.
6. If a crosstalk measurement is necessary, it should be performed at a low current, where the effects of
crosstalk are noticeable. First, if (old) values for VFEEDx exist in the meter, they are entered in the
spreadsheet in the row labeled “Old VFEEDx”, one for each phase. If these factors are zero, “0” is
entered for each phase.
7. Test current and test voltage are entered in the yellow fields labeled VRMS and IRMS.
8. The crosstalk measurement is now conducted at a low current with phase angles of 0° and 180°, and
the percentage errors are entered in the yellow fields labeled “% error, 0 deg” and “% error, 180 deg”,
one pair of values for each phase. The resulting VFEEDx factors are then displayed in the green fields
labeled VFEEDx.
