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User Manual
i Series / iX Series 121
6.6.3 Output Impedance Calibration (3001iX, 5001iX, 9003iX, and 15003iX models only)
For the output impedance calibration, two HP 34401A DMM's or equivalent must be used. The
following modes must be programmed: 6 digits, AC Filter, slow: 3 Hz and 6 digits. One DMM is
used to measure the output voltage, one to measure the load current using a suitable CT. The
calibration should be done for each phase individually. Furthermore, an accurate phase meter
with at least 0.01° resolution is needed. (See equipment list section 6.1). The reference input of
the phase meter must be connected to the LOCK output of the controller at the rear panel of the
master 5001iX chassis. This is a square wave TTL signal. Select Square wave input on the
phase meter. The other input of the phase meter must be connected at the AC source output of
the phase being calibrated. Select Sine wave input on the phase meter for this input. Note that
this is a 230 Vrms signal so the Phase Meter must have sufficient input range on this input. The
phase meter is used to determine the phase shift between no load and full load conditions (
).
Connect the test equipment required as shown in Figure 6-2. If the DMM and phase meter have
an IEEE/GPIB interface, it is possible to use the 16-bit version of the CIGUI program version 3.18
or higher supplied on the CD ROM that came with the iX Series to operate the test equipment.
The 16-bit CIGUI requires a Windows 98 PC. (This function is not included in the 32 bit Cigui32
program however).
The calibration for impedance can be found in the Calibration Menu on the main CIGUI screen.
In this case, the GPIB interface must be connected to the PC, the DMM's and the Phase meter.
The GPIB addresses for the DMM's and Phase meter expected by the CIGUI program are
shown in the table below.
Instrument Address
iX AC Power Source
(Do not use 4,5 or 6 for AC source) Set in CIGUI Interface screen
and Utility Menu on iX
controller.
DMM1, Used for voltage measurement 4
DMM2, Used for current measurement 5
Phase Meter, Used for phase measurement 6
Table 6-6: GPIB addresses for impedance calibration
Note that the CIGUI32 (32 bit version) does not support computer aided impedance calibration.
Instead, the readings from the DMM's and Phase meter can be made manually and written
down. In that case, a calculator may be used to calculate the R and L portions of the impedance
using the formulas shown in Table 6-8.
To verify or adjust the programmable impedance function, proceed as follows for each phase:
1. Program the power source to 230.0VAC and 50Hz.
2. Program the output impedance resistance and inductance to the lowest values from the
OUTPUT IMPEDANCE screen. This will be the IMP. REAL MIN and IMP. REACT MIN
values that have been set in the OUTPUT CAL screen. Press the PHASE key to select the
phase to be calibrated. (A, B or C).
3. Measure the output voltage of the power source with no load and record this value (V
NL
).
4. Using a resistive load bank, load the output of the power source to about 16 amps. Measure
the output voltage of the power source under load and record this value (V
L
). Also measure
the load current and record this value. (I).